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Project Specific Discussions => Dynamic Processors => Topic started by: orson whitfield on June 22, 2004, 03:55:29 PM

Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 22, 2004, 03:55:29 PM
Tadgos,  are you here? Well,  if you are, please excuse me.  It's time for a new "1176 Repost" thread and I'm taking the honor of being the one to start it.  (All complaints to Gyraf - he inspired me) :green: .

I used a color code chart http://www.breakup.de/resources/resistor.html to check the values of all resistors on the Printed Circuit Board of my G1176.  I found one incorrect resistor - the 82R, right below Q3; it was a 1.8K :?   As I have stated elsewhere, I had high voltage at the collector of Q2 ( 2.83 instead of something close to the posted 1.76 on Jakob's schematic). Well, apparently,  this 82R made a difference.  The Voltage is now right on the money.  Now I'm gonna check the rest of the voltages Jakob posted.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 22, 2004, 05:12:38 PM
Are these tolerable?
           C           B           E
Q2 ---1.76V --.501V -- .997V
Q3 ---11.70V - 1.76V -- 1.16V
Q4 ---29.9V ---11.7V---11.11V
Q5 ---28.19V --4.82V---4.38V

Q6----14.87----27.56----28.7
Q7----14.87----28.72----29.34
Q8----29.90----14.87----14.21
Q9----14.16----13.59----

Q12---14.71----4.38-----3.85
Q13---        ----14.71----14.13
Q14---        ----2.85------3.39
Q15---        ----16.66----16.12

According to notes I took from the old "FEEDBACK FOR GYRAF 1176LN (repost)" thread ,  "a rule-of-thumb is around 0.6V less on the emitters than on the bases."  I think I might have written down some numbers in the wrong column but my ratios appear on track with this statement.

Also,  here is a list of DC voltages that some one who had a working unit posted in the "FEEDBACK FOR GYRAF 1176LN (repost)" thread ,

E B C
Q2 0.54 1.05 1.77
Q3 1.16 1.77 12.4
Q4 11.83 12.42 30.3
Q5 4.54 4.96 28.59
Q6 29.12 28.56 14.63
Q7 29.75 29.12 14.62
Q8 14.01 14.61 30.29
Q9 13.94 13.33 0.002
Q12 4.03 4.59 15.12
Q13 14.5 15.12 30.28
Q14 2.9 3.508 17.28
Q15 16.7 17.28 30.3

Here I noticed my voltages are all a little lower than his.  Is this O.K.?  The voltages I get at Q2 are very close to Jakob's so i think Q3 might need replacing.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 23, 2004, 04:29:36 AM
Hi Orson,

If the unit is working and sounding kinda okay, you shouldn't worry about how the transistors are doing. If one messes up, you will surely find out very soon.

Is the unit working as it should?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 23, 2004, 10:10:20 AM
Well,  I haven't listened to it yet because I know I have  to still calibrate it.  From what I have read around here,  you need to calibrate it to be able to tell it's working correctly.  Where can I find the instructions for calibrating.  Deanp920,  are you here?  You were helping me out b4 the switch.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 23, 2004, 11:54:00 AM
(..) (from old RO answer)
Quote
.. first you should check id you have the FET "bias" pot set roughly correct:

This is the 2K2 trimmer pot, marked "Q BIAS", located in the "GR Control amp" section. Try turning this with signal through, and see if something happens.

The proper adjustment of this trimmer is made like this:

Input a weak signal, around -10dB or something, and measure the AC output level without gain reduction:

Set the attack and release controls fully clockwise, the ratio to 1:4, and the output level to max. Turn the input level so you get something readable, like 100mV on your voltmeter on the output.

Now adjust the "Q Bias" trimmer untill you have a 1dB drop in output level. That's it. This control makes sure that the FET is set just in the beginning of it's cut-off range prior to actually beginning gain reduction.

The low input voltage is to make sure that no gainreduction should occur when you're doing this adjustment.

If its initial position is set to a larger drop, you have to readjust the input level control.

Hope this helps...

Jakob Erland
Gyraf Audio
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 23, 2004, 10:35:30 PM
Ok good news.  The unit is working and sounds perfect. :shock:   :razz:
THe problem was A) one wrong resistor(1.8k Ohm instead of an 82 Ohm),  B) two burned out resistors (the two right before or after the BD517 and BD 518), C) needed to replace the BD517 and 518 and C) needed to replace the voltage regulator (7824).  The unit sounds dramatically better than it did before i droped the pcb one inch inside the chasis while testing voltages two months back.  So even though droping it broke a few parts and caused me a detour, the end result is better.  

Calibration time.  Some one gave me an old Leader LAG-125 Low Distorion Audio Generator for free.  I guess this is useful for calibrating?  It's cool because on it's meter it shows R.M.S. Volts and dB with  "0db=0.775V" written on the left side.  I guess when you say to back off the signal till you get a 1 dB drop,  I could do the formula or just look at the meter.   THanks to Deanp920 big time for getting me through this.  Ofcourse, I thanked everyone who ever helped me at anystage of this project over the last 15 months at the old location (Tech Talk )  I wish I had a record of that post but there were about 12 of you who helped (Jakob, SSltech, Mark Burnley, Frank Rollen, Kev, Deanp920,  Chris V, and others)  I can't remember at the moment.  THanks again guys.  No cracking open the bottle till i get it calibrated, though.  THen I'll get plastered.  :wink:  :sam:  :thumb:  :grin:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 24, 2004, 03:48:03 AM
That's good news, Orson!

Keep us updated on the calibration..

Jakob E.
Title: g1176
Post by: romeojesus on June 24, 2004, 04:00:15 AM
what parts of the g1176
(besides 5532)
would you guys suggest to put in sockets
instead of soldering directly on the pcb?

christian
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 24, 2004, 04:02:43 AM
The two FET's

There's a good chance you'll be changing these around.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 24, 2004, 09:03:07 AM
Ok I need to know which pins to hook up for both signal input from the signal generator and to measure the output with a Multimeter.  THanks.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 24, 2004, 10:03:15 AM
Alright I think I figured it out BUT ...  

"4: "GR meter Trck" (tracking). Set ratio to 1:20, set Meter to bypass. Input a 1kHz, 50mV signal. Set input level to ~12'oclock. Set output level so you get 50mV at the output also (now you have unity gain)."

I can't get anything higher than 20.9 mV at my output.  Whats wrong?  Also, I amchecking voltages using AC setting on my multimeter. thats ok?
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 24, 2004, 10:09:33 AM
When I turn the Output knob on the G1176 I get no difference in mV's.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 24, 2004, 11:02:15 AM
Ok there are some weird things happening here.  First off the unit is not working as it should,  I spoke too soon.   :cry:  The release knob does nothing and the Attack knob is controlling the release.  hmm.. maybe I just mislabled?  Nah just checked the Gyraf site attack is on top as I have it.  So I guess I wired it incorrectly.  The never ending project continues.
Title: All things G1176 - the new "repost" thread.
Post by: dmlandrum on June 24, 2004, 11:20:17 AM
Okay, I have a question that I know has been addressed on the old forum.

I have two 1176 PCB sets courtesy of Gustav. I would like to build both of them into a single 2U chassis. Now, although it would still be spiffy to have two units in one box, it would be even spiffier to have them linkable to work in stereo. I remember reading on the old board that this is possible, but I can't remember how or what the link was. Can anyone point me in the right direction? I do know I'll need to hand-match four FETs, which will be tedious but not really impossible.

Thank you all for the help!
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on June 24, 2004, 12:12:11 PM
I have 4pdf schematics about a stereo compressor based on urei 1176. I download them some months ago, but i dont remember where i found it. I can send to you by mail if you want... The title in schems is "JH .FC2 Stereo Compressor based on Urei 1176 J.Haible 2001"

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 24, 2004, 12:19:24 PM
Ok  I simply had the switches in the wrong holes.  And I think the attack is working but I really can't tell much.  How do you know if the attack is working?  Is it a dramatic thing?  Also,  after a while of being on I get intermitent noise and low frequency pops;/crackling,  kinda sounds like a dirty pot turning.  If I move the unit it seems to go away a bit but not consistantly.  I checked the voltage regulator heatsink and, man,  it was hot!  I know this is not good.  It supposed to be hot but not to a temperature where you can't keep you finger on it,  right? I am thinking there is a connection between the voltage regulator getting hot after time and this noise.    I am testing out to see.
Title: All things G1176 - the new "repost" thread.
Post by: dmlandrum on June 24, 2004, 12:19:43 PM
I'm sure there would be plenty of people interested in seeing that.

Go ahead and shoot them to me! consul [at] studioconsul [dot] net  (just replace the bracketed words with the usual symbols.) :wink:

I can post them to my web space if anyone else is interested. Thank you very much, Apache5!
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on June 24, 2004, 12:34:04 PM
I sended it to you.... i hope that it would be usefull for you ;)

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: dmlandrum on June 24, 2004, 12:44:17 PM
I received them just fine, Apache5.

For the rest, I have uploaded these to my webspace, but I want to make sure it is okay to post links to these. Any issues with that, Apache5?

Thank you again!
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on June 24, 2004, 01:13:41 PM
There is no problem for me, but i dont know very much about copyright laws in these situations, and the schems are not mines. If its for my wishes id like that you will post links to them ofcourse  and these links are only to informative purposes, not to lucrate with them, i think that its ok, isnt it?

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: dmlandrum on June 24, 2004, 01:16:32 PM
Okay, here are the links:

http://studioconsul.net/techtalk/stereo1176/jh_comp_psu.pdf
http://studioconsul.net/techtalk/stereo1176/jh_fc2_sch1.pdf
http://studioconsul.net/techtalk/stereo1176/jh_fc2_sch2.pdf
http://studioconsul.net/techtalk/stereo1176/jh_fc2_sch3.pdf

Very interesting stuff, but it wasn't exactly what I'm after. I remember a posting on the old board about some device that can link 1176s in stereo.

Thank you much for the info anyway, though, Apache5. And if anyone wishes me to take these schematics down, I will do so post haste.
Title: All things G1176 - the new "repost" thread.
Post by: boodthee on June 25, 2004, 05:26:43 AM
Hi Consul and everybody else!

First of all (as this is my first post), I want to say thank you to everybody here for this great forum and especially to gyraf for the great projects!

I am currently in the process of building a dual 1176 which I also want to make stereo linkable. I was about to ask the same question as Consul here...
What I found on the net is this schem of the 1176 Stereo Adapter
http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-1176SA.pdf
But on the other hand I think somebody said (somewhere?!) that it would be possible to just connect the units as is...?!?
It would be great if someone could explain what the stereo adapter circuit is actually doing as I don't fully understand it...what is the battery for? And is it possible/advisable to link two 1176s directly?

Thanks in advance
Stephan
Title: All things G1176 - the new "repost" thread.
Post by: mnats on June 25, 2004, 08:13:23 AM
There was a good thread that covered stereo linking but it must have been at the old forum. From memory the thread went like this: someone tried various published circuits found on the internet. The JBL document contained what was thought to be an error in the resistor value. It looked like someone penned in a new value on the BOM in the UREI-1176SA.pdf document. The Purple Audio circuit was similar and also didn't work properly. I believe one or the other caused excessive battery drain. I think deanp920 had two linked fairly closely by simply matching the two gain control FETs.

Apparently without trying it out himself, Jakob casually tossed out a suggestion for modifying the stereo link circuit and suddenly everyone had a working stereo link when all previous published circuits failed. I must have archived it somewhere and will post back when I find it unless this jogs someone else's memory.
Title: All things G1176 - the new "repost" thread.
Post by: The Landlord is Dead on June 25, 2004, 03:39:10 PM
I can't  find the BD518/517 driver transistors nor the replacements suggested at the NRG web site.

 I read somewhere that they can be swapped with NTE189 & NTE128P, in stock and available at mouser. Anyone try this? Are they pin compatable?
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 25, 2004, 04:28:08 PM
THE FOLLOWING ARE QUOTES I GATHERED FROM THE OLD REPOST THREAD REGARDING THE BD517 and BD518:

"BD518 = NTE189 - check with swedish chef, has some 518's that are replacements from Jakob
BD517 = NTE128P"


"BD517:
..And also make sure that you've mounted BD517/518 correct: one is oriented opposite of the other..-- check with swedish chef, has some 518's that are replacements from Jakob

NTE 128P's for the BD517's
I got the BD518 and BD517 from www.telepart.co.uk.

BD518:
..And also make sure that you've mounted BD517/518 correct: one is oriented opposite of the other..- check with swedish chef, has some 518's that are replacements from Jakob

NTE 189's for the BD518's
I got the BD518 and BD517 from www.telepart.co.uk. "
Title: All things G1176 - the new "repost" thread.
Post by: mnats on June 25, 2004, 06:03:16 PM
Quote from: "The Landlord is Dead"
...nor the replacements suggested at the NRG web site.

BD135 @ Mouser (http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=456489&e_categoryid=241&e_pcodeid=51230)
BD136 @ Mouser (http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=457174&e_categoryid=241&e_pcodeid=51230)
Lots of their stuff doesn't appear in the print/.pdf catalog. Just do a search on their site.
Title: All things G1176 - the new "repost" thread.
Post by: Jonathan Hayward on June 25, 2004, 06:30:29 PM
Orson, you sorted?

the attack is dramatic comparing fully ccw to cw, try speech or recorded speech.

The unit needs a shot while 1/2 hour on the safe side to warm up to a stable temp. My regs were too hot to touch so maybe don't worry about that if the supply voltages are good (-10/+30), but does your intermittent noise happen after this warm-up?

I'd really recommend even a cheap old scope for this project (evilbay £10 job), espesh as you already have the signal gen., you really get to understand its operation more clearly.
Title: All things G1176 - the new "repost" thread.
Post by: The Landlord is Dead on June 25, 2004, 06:32:35 PM
BD135 @ Mouser
BD136 @ Mouser

These have a minimum of 2000 per order. I'll just stick with NTE suggested replacements. It brings up a question though, what does it mean when they add an "S" or "STU" at the end of a product number. As in BD13510S or BD13510STU instead of just BD135. I assume you just can't automatically swap.
Title: All things G1176 - the new "repost" thread.
Post by: Jonathan Hayward on June 25, 2004, 06:53:42 PM
no suffix, S and STU are basically the same thing. If you look here
http://www.fairchildsemi.com/pf/BD/BD135.html

the page heading is bd135, but it shows the two suffixes being different packing methods, the packAGE - the TO-126 case - is the same.

If you get really stuffed, I'll post you a reasonably matched pair (136/137) which I used in my first 1176 - some of my haul from a skip after the Lewes flood.
Title: All things G1176 - the new "repost" thread.
Post by: mnats on June 25, 2004, 08:54:02 PM
Quote from: "The Landlord is Dead"

These have a minimum of 2000 per order.


Sorry, yeah gotta watch out for those minimums from mouser. I also offer to send you a pair of 135/136s if you get stuck.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 25, 2004, 08:58:05 PM
Johnathan,

Thanks for asking.  I checked the -10V/+30V and the numbers were darn close,  closer than ever before but I didn't stop to see if there was a "-" next to the 10V places.  Oh well,  on my way to a gig so I don't have time to check again but i guess they were negative.  THe point is the read outs were very close to what they are supposed to be.  Ok next thing,  the intermittent noise.  Its all gone!  I don't know what it was but its not back. :?  :roll:   Lets hope it stays that way.  By the way I am on the look out for an ascilloscope,  thanks for the rec.  

Now,  for the attack situation,  I recorded myself reciting a tongue twister into Logic Audio (emagic) and looked at the wave file overview to inspect the differences between a full ccw setting and a full cw setting.  The difference was that full cw limited the peaks and full ccw position allows the peaks to be a lot higher.  For this test,  I set the compression to 1:20.  I guess the results are normal and expected;  a fast attack doesn't let a lot of volume out the gate and vice versa for slow attack.  I guess I expected a different result out of a 1176 style compressor where a slow attack really meant slow attack.  Here it's really hard for ME to tell that it's slower.  Overall it just sounds lower volumed and "compressed".  (To all you people rolling your eyes right about now,  remember I have never twisted the knobs of a real 1176 before,  so I wouldn't know what they do).I also noticed a slight attenuation of the high frequencies aswell when the attack was set full cw.  So,  does this sound like its working to you?

Below are questions I posted but no one addressed.

Instructions on calibrating the G1176 from Gyraf web site:

"4: "GR meter Trck" (tracking). Set ratio to 1:20, set Meter to bypass. Input a 1kHz, 50mV signal. Set input level to ~12'oclock. Set output level so you get 50mV at the output also (now you have unity gain)." -

When I do this,  I can't get anything higher than 20.9 mV at my output.  Also, I am checking voltages using the AC voltage setting on my multimeter.  Is that the correct setting or is DC?  
When I turn the Output knob on the G1176 I get no difference in mV's.

Thanks for the patience and continued help.  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on June 26, 2004, 12:11:31 AM
Quote
Below are questions I posted but no one addressed.

Instructions on calibrating the G1176 from Gyraf web site:

"4: "GR meter Trck" (tracking). Set ratio to 1:20, set Meter to bypass. Input a 1kHz, 50mV signal. Set input level to ~12'oclock. Set output level so you get 50mV at the output also (now you have unity gain)." -

When I do this, I can't get anything higher than 20.9 mV at my output. Also, I am checking voltages using the AC voltage setting on my multimeter. Is that the correct setting or is DC?
When I turn the Output knob on the G1176 I get no difference in mV's.
Orson, If you use your DMM, you MUST stay within its' AC frequency response range, which is probably no more than 400Hz. Check your manual. There's no telling what reading you'll get at 1Khz. Stay around 250Hz so you can at least discount any errror in your meter.

Another crude yet effective meter is the software version of a VU meter that can be downloaded for free from PSP Audioware. You can calibrate it and everything! Works OK in a pinch.

Your DMM at a lower test freq.(250Hz) is much better, though.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: jhaible on June 26, 2004, 03:53:50 AM
Quote from: "Apache5"
I have 4pdf schematics about a stereo compressor based on urei 1176. I download them some months ago, but i dont remember where i found it. I can send to you by mail if you want... The title in schems is "JH .FC2 Stereo Compressor based on Urei 1176 J.Haible 2001"

Arnau



You can find it here:
http://home.debitel.net/user/jhaible/hj.html

JH.
Title: All things G1176 - the new "repost" thread.
Post by: al_p on June 26, 2004, 03:58:43 AM
Hey Guys

i'm getting ready to put together a G1176. i just noticed the min order for the BD135/BD136 too. ouch. i guess i?ll go with the NTE subs.

one quick question. the push button switch banks on the REAL 1176, are these interlocking or latching? i know when you engage a new selection the previous selection disengages. but i got confused and forgot which is which. i THINK it?s interlocking...but i am seeking confirmation.

i'll hopefully be back in this thread next week, when constrution begins.

-AL
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 26, 2004, 10:44:48 AM
Ok I think  :roll:  its callibrated.  Is it normal for the Vu needle to be at - 20 when the compression is set to 1:4?  The only time it's at " 0 " is when the compression ratio is set to 1:20.  Once I reached the point where "the output level [was] half the input level",  I set the "GR meter Trck" trimmer so the VU-meter read -6dBVU. But I was only able to do that after I played with the zero meter trimmer.  I then "remove[d] [the] input signal and (re)set "GR meter Zero" for a reading of 0dBVU".  This was the only way to get it set.  Am I on track here?  And by the way my DMM measured freq. from 10 Hz to 40mHz.
Title: All things G1176 - the new "repost" thread.
Post by: The Landlord is Dead on June 26, 2004, 11:43:53 AM
Quote
i'm getting ready to put together a G1176. i just noticed the min order for the BD135/BD136


Looks like http://www.digikey.ca/ has them without a minimum order.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on June 27, 2004, 01:08:04 AM
Quote
And by the way my DMM measured freq. from 10 Hz to 40mHz.


NO, that is referring only to the frequency values the meter will measure; ie., telling you what frequency a particular signal is alternating at. That specification has NOTHING to do with frequency response, Orson.

You are trying to measure the AMPLITUDE of a particular signal at a particular frequency.

Unless your meter is a very new one and cost better than $250, it probably won't make accurate AMPLITUDE measurements at frequencies over 400Hz.

Check your manual again.
Quote
Am I on track here?


I don't think so.

I think Mark Burnley posted a copy of my post from the the "More Gain" thread in the old forum where I wrote down all my calibration levels and voltage gains, including a synposis of the surrounding details of my test procedure. Find that info and try to duplicate those conditions. The numbers provided there reflect the G1176 working properly in its' unmodified condition. Just drop your test frequency to 250Hz to be safe side.
Quote
Is it normal for the Vu needle to be at - 20 when the compression is set to 1:4? The only time it's at " 0 " is when the compression ratio is set to 1:20.


It is impossible for us to know what that means without you providing details of the test conditions; ie., input signal level, where all the controls are set, etc.

Find a solid frame of reference(like the one I mentioned above), document it the next time you post for help, and let's go from there.

Take care,

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 27, 2004, 01:00:13 PM
Quote from: "deanp920"

It is impossible for us to know what that means without you providing details of the test conditions; ie., input signal level, where all the controls are set, etc.


THank you Dean.  What I meant was when NOTHING is plugged into my G76 and the power is on and I set the compression ratio to 1:20 the Vu needle is at 0.  When I adjust the ratio to 1:12 and lower the needle gets closer to the left.

I am looking for that info.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 28, 2004, 06:50:09 AM
If the FD333 diodes are leaky, there will be a small difference in meter zero resting position depending on ratio. But it should not be more than +/- one dB or so on the meter scale.

Are you using "real" FD333 diodes, or a substitute?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 28, 2004, 06:21:56 PM
I believe I have the correct specified part.  I ordered part number 18C6399,   Fairchild semiconductor FDH333.  Here is the link from Newark:
http://www.newark.com/NewarkWebCommerce/newark/en_US/support/catalog/productDetail.jsp?id=18C6399

And here are it's specifications:
http://www.fairchildsemi.com/ds/FD/FDH333.pdf
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 29, 2004, 06:34:34 AM
I think we have had this problem before - in the old giant thread. But I don't remember what we did to fix it.

If GR meter indication changes (and stays changed) when ratio is changed, but with no input signal, then either the diodes or c19/c20 - the two DC-blocking capacitors in the sidechain rectifier - must be leaking.

Or maybe your meter-FET is much more sensitive than your audio-fet, and thus indicates too much change.

Try letting a sub-threshold signal through (some 25mV or so) and check if the signal level is also affected by the ratio switch.

Also check how DC-levels( signal and no-signal, different ratios) behave at point7 , where your control voltage can be read out.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Svart on June 29, 2004, 09:05:32 AM
get bd135/136 at www.newark.com in the US.  now what about those 4.7m linpots and 22k linpots, where the heck did you get those??  i found 4.7m ones but the element is actually built in the knob so it can't be replaced, the are 6$usd a peice and they don't come in the other configs we need to use them for all the pots!!  WTF?
Title: All things G1176 - the new "repost" thread.
Post by: jhaible on June 29, 2004, 09:18:50 AM
Quote from: "Svart"
get bd135/136 at www.newark.com in the US.  now what about those 4.7m linpots and 22k linpots, where the heck did you get those??  i found 4.7m ones but the element is actually built in the knob so it can't be replaced, the are 6$usd a peice and they don't come in the other configs we need to use them for all the pots!!  WTF?



I got the pots from www.reichelt.de .
Crappy RadiOhm carbon pots, but there is not much alternative for 5 meg values.

But for my next 1176 clone, I'll use rotary switches with resistors instead of the attack / release pots. I think 11 positions are ok dor attack / release. The level knobs will be high quality pots, of course.

JH.

JH.
Title: All things G1176 - the new "repost" thread.
Post by: Learner on June 29, 2004, 09:27:52 AM
speaking of pots, where did you get the frequency pot for your JH-5 synth?
Title: All things G1176 - the new "repost" thread.
Post by: tubejay on June 29, 2004, 10:12:25 AM
Would this 5 meg pot work?  It's www.Digikey.com part number RV6L505C-ND, or this number CT2361-ND, or this 308N505-ND.
Title: All things G1176 - the new "repost" thread.
Post by: jhaible on June 29, 2004, 10:29:08 AM
Quote from: "Learner"
speaking of pots, where did you get the frequency pot for your JH-5 synth?



The pots are standard multiturn pots, Spectrol if memory serves.

You probably mean the dials; these are surplus stuff from Siemens.
Similar dials are carried by most electronics suppliers (quite expensive, in the 20 ... 30 Euro range), though not the very same ones.

JH.
Title: All things G1176 - the new "repost" thread.
Post by: Learner on June 29, 2004, 10:35:04 AM
Quote from: "jhaible"
Quote from: "Learner"
speaking of pots, where did you get the frequency pot for your JH-5 synth?



The pots are standard multiturn pots, Spectrol if memory serves.

You probably mean the dials; these are surplus stuff from Siemens.
Similar dials are carried by most electronics suppliers (quite expensive, in the 20 ... 30 Euro range), though not the very same ones.

JH.


Hi JH,
Yes, that's what I meant the dial knob. I have never seen anything like it from any electronic stores........GREAT STUFF BTW! :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: jhaible on June 29, 2004, 10:43:42 AM
>Yes, that's what I meant the dial knob. I have never seen anything like it >from any electronic stores

You might want to look at www.rs-components.de and type 509428
into their search function. Not ecatly the same, but close enough.
Or try 3576831 for a similar one.
Another impressive looking dial would be 509973.

JH.
Title: All things G1176 - the new "repost" thread.
Post by: Learner on June 29, 2004, 10:49:55 AM
COOOOL!!!  :grin:

Thanks JH!!! :thumb:

 :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: Svart on June 29, 2004, 06:30:28 PM
hey guys, i found 5m and 25k pots.. www.mouser.com  31VA605 for the 5M and 31VA403 for the 25k.  they are 1.25$usd a peice.  they also have all the other values too so they will all be the same style.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 29, 2004, 07:31:31 PM
Hey ya'll,

Take a look at the 47 capacitor on the main pcb diagram and tell me if it's pf or uf.  It's right next to the 470k resistor and close to Q12 and q13.  I put a 47uf in there but I am not sure about this move.  Thanks.
Title: All things G1176 - the new "repost" thread.
Post by: Mark Burnley on June 29, 2004, 07:34:31 PM
Hi Orson!

How's it going?

Yea, the cap near Q12 and Q13 is a 47uF electrolytic cap (C18 in the Gyraf schematic)

Are things all good now you've done your bias setup?

Mark
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 29, 2004, 07:45:37 PM
Thanks Mark,  

Afraid not.  Read page 3 and see where I stand.  Basically my Vu meter is not reacting properely.  It drops dramatically with each setting of the compression ratio switch -1:4 moves it far to the left and 1:20 is at 0.  Jakob mentions a "point 7 " on the board - where is that?
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on June 29, 2004, 08:12:07 PM
Thanks SVART...

 If those should work...I'll use those.

  :sam:  :wink:
Title: All things G1176 - the new "repost" thread.
Post by: tubejay on June 29, 2004, 08:18:31 PM
Quote from: "Svart"
hey guys, i found 5m and 25k pots.. www.mouser.com  31VA605 for the 5M and 31VA403 for the 25k.  they are 1.25$usd a peice.  they also have all the other values too so they will all be the same style.


Thanks Svart!  I'm going to copy this info over to the parts thread, just to keep it there as well, because that's the comprehensive list for north america.  

What effect will increasing the value of the attack and release times have on the attack and release time?  Will it just allow for slower attack and release times at one end of the pot?

Thanks,

Jay :thumb:
Title: 1176 VU-Meter
Post by: xsmsx on June 30, 2004, 09:27:01 AM
Hi there,

this is my first entry, but I already solved some problems with the help of this thread.
Unfortunately this time I couldn't find the topic that answers my questions.
I just finished a 1176 and it seems to work. The only thing that doesn't work is the VU-Meter which is kind of a no name product. No reaction at all. The meter works fine if I put it in my SSL-Clone where I normally use a Behringer Meter (like discussed in another thread). It shows the same values. None of those two work in the 1176.
Does anyone know the solution???

Thanks
Christoph
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 30, 2004, 09:32:18 AM
Hi Christoph,

Welcome to The Lab.

There is quite a difference between the meters in the SSLClone and the 1176.

The 1176 meter MUST be an AC-reading type - the one with an integral diode bridge. The SSL-Meter on the other hand, is a normal DC-reading type.

To use a DC-meter with the 1176, you'll need to mount it with a diode-bridge, four (preferably germanium) diodes rectifieng the signal to the meter. And then add a resistor in series, so that the sensitivity is around showing 0dB VU at +4dBM signal level.


Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 30, 2004, 09:41:42 AM
Quote from: "gyraf"
I
Also check how DC-levels( signal and no-signal, different ratios) behave at point7 , where your control voltage can be read out.

Jakob E.


Point 7?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 30, 2004, 10:12:58 AM
Point7 referring to the schematic - where the stereo interlink could have been placed.

You can e.g. find this point at the ratio control pcb, right where attack and release pots meet...

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 30, 2004, 01:11:16 PM
Quote from: "gyraf"

Try letting a sub-threshold signal through (some 25mV or so) and check if the signal level is also affected by the ratio switch.


Yes the signal level is also affected by the ratio switch.

Quote from: "gyraf"

Also check how DC-levels( signal and no-signal, different ratios) behave at point7 , where your control voltage can be read out.

Jakob E.


DC-levels change with the turning of the ratio switch with and without signal applied.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 01, 2004, 04:04:08 AM
So the DC levels change at point7 with ratio, and stays changed?

The second part of the ratio switch, with R42-43-44-45-46-87 and C21, adds different negative bias'es to the anode (-side) of the FD333 diodes. This is the "threshold" to be overcome before the two FD333 diodes conduct and start gainreduction.

Check your DC voltage at point 21 with no signal. It should be between 0 and -10V, but in any case below 0V.

Try lifting one end of both the FD333 diodes, and recheck if ratio alters gain (it will change a little, but not much). If so, then the ratio setting affects the "Q-bias" - possibly because of an error around R74-75 and C21. Check orientation of C21.

Also, this could be because of an error in either C19 or C20 - if one of these are leaking DC, then you'll have constant over-threshold DC at the input of the diodes.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 01, 2004, 08:54:06 AM
Maybe I have the incorrect value at C21.  The schematic shows a 100/+25V.  I have a 100uf 35V there.  I think I remember asking if this was ok but I'll make sure now.  Is it?
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 01, 2004, 09:59:47 AM
Quote from: "gyraf"
Check your DC voltage at point 21 with no signal. It should be between 0 and -10V, but in any case below 0V.
Jakob E.


I haven't done the other things yet but this did result in voltage below 0V in every setting of the ratio switch with no signal passing.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 01, 2004, 11:59:23 AM
Quote from: "gyraf"
So the DC levels change at point7 with ratio, and stays changed?
 YES

Quote from: "gyraf"
Check your DC voltage at point 21 with no signal. It should be between 0 and -10V, but in any case below 0V.
YES IT IS.

Quote from: "gyraf"
Try lifting one end of both the FD333 diodes, and recheck if ratio alters gain (it will change a little, but not much). If so, then the ratio setting affects the "Q-bias" - possibly because of an error around R74-75 and C21. Check orientation of C21.
YES IT DID CHANGE. I checked the orientation of C19, C20 and C21.  All were o.k.


Quote from: "gyraf"
Also, this could be because of an error in either C19 or C20 - if one of these are leaking DC, then you'll have constant over-threshold DC at the input of the diodes. Jakob E.
So I guess the thing to do at this point is to get new caps for C19, 20 and 21? Does the fact that the meter changes with the ratio setting change the performance of the unit?
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 01, 2004, 12:40:49 PM
:shock:  Oh boy!  Here I am about to resolder the FDH333's back into place and I notice a hole in the PCB not filled by the leg of anything.  After a careful look I see that I have the 1000/35V electr. cap with both legs near each other when it appears that one of them needs to be in that open hole. Before I change this could some one tell me if I am not seeing this right?  It's cap to the immediate right of BD517.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 01, 2004, 12:46:03 PM
If the gain/meter changes with different ratios even when the two diodes are lifted, then the problem must come from a point later than this.

So C19-20 are probably alright.

C21 100u/35V is fine. You can always use higher voltage rating - it's a maximum rating.

The only thing I can think of that would provoke this error, is shorts or wrong resistors around the ratio switch. That is, the second part of it, where the negative offset is added to the rectifier. Somehow this influences your "Q-bias" backwards, and it should'nt.

The voltage at point21 SHOULD change between some -5V and the voltage set with "Q-bias", when you adjust ratio. Check that this happens.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 01, 2004, 12:56:35 PM
Orson,

That 1000u/35V is just an extra reservoir cap for the +30V. You could get a bit more noise if it's not there, but I don't think that this is your problem. There are two pcb holes - to accomodate wierd-size caps.

Jakob E.
Title: Wiring pots.
Post by: salty on July 01, 2004, 06:42:54 PM
Hi I'd like to say a big thankyou to everyone on this board most definitely including the people asking questions!!

I'm making a G1176 at the moment and I'm currently at the stage of fitting all the wiring to the board and mounting it into the box. To be honest I'm stuck here, I don't know which of the 3 legs of the potentiometers to put to which hole on the board. Can anyone help me please?

BTW I couldn't get a 4.7m pot anywhere, so I bought a 2.5m pot and a 2.5m resistor and a switch. Which leg of the pot should I fit the switch/resistor to?

thanks,

Nick Salt
Title: All things G1176 - the new "repost" thread.
Post by: Svart on July 01, 2004, 07:25:08 PM
where are you from salty?  in the USA, mouser sells 5M pots.  let me find the part number...31VA605.  it's made by alpha.  they are 1.25$usd a peice.  all the other pots can be purchased from the same series too so they all match.
Title: All things G1176 - the new "repost" thread.
Post by: salty on July 01, 2004, 07:40:07 PM
Hi Svart,

I'm in Newport, South Wales, UK. Farnell has been my supplier so far. I'm quite happy to go with the switched release pot, in fact I'm quite proud of my humble solution, it's making the thing more mine ;)

If this unit goes well I will definitely be building another 2 or 3 of them as I would like a 1176 on snare and room mics simultaneously, and I needed to order 10 of most of the resistors from Farnell leaving me with a surplus.

Anyway to the point eventually - If my switch thing turns out to be a pain in the neck I'll need to find a 5m pot, and Farnell only seem to have the trimmer type, so I may have to order from the US - cheers for the info mate.

Salty
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 02, 2004, 05:20:38 AM
Salty,

Page1 in the G1176 layout .pdf has a description on how to mount the pots.

For the resistor in series with the release pot, are you thinking of using a potentiometer with integral switch? In that case, connect the resistor across the switch, connect one end to the start of the pot, and use the other end of the switch as potentiometer end. This way you have the resistor in circuit only when you turn release speed all the way down to the click.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 02, 2004, 04:04:49 PM
Jakob,

Does the problem I have with the meter effect the operation of the compressor itself?  If not,  I would like to call it quits on this.  I really don't care anymore if the meter is accurate.  I just want a compressor that sounds good.  At this point, I am burned out and don't think I will make my next project one that needs to be calibrated in any way.
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 02, 2004, 09:45:41 PM
Jakob or anyone who has built this,

When the meter switch is in bypass mode should the meter still display the output signal ?
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 02, 2004, 09:54:01 PM
I never could find the stereo link diagram from the old forum on my HD. Does anyone have the modified stereo link that Jakob altered to make work?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 03, 2004, 01:29:55 AM
Quote
I never could find the stereo link diagram from the old forum on my HD. Does anyone have the modified stereo link that Jakob altered to make work?
Hi,

It is really simple: just put the series resistor(82k) on the other side of the pot; the circuit will still work the same but will allow you to adjust up to zero offset, say, if your FET's are perfectly matched...although with the matched FET's you can simply connect the two points without the circuit and be just fine. Rig the circuit on the JBLservice schematic like I've explained here and you'll have no problems.
Quote
Jakob or anyone who has built this,

When the meter switch is in bypass mode should the meter still display the output signal ?
No, the meter is OFF in bypass mode.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 03, 2004, 06:14:07 AM
Quote:
Jakob or anyone who has built this,

When the meter switch is in bypass mode should the meter still display the output signal ?
No, the meter is OFF in bypass mode.

Dean

Thats interestng because both sets of calibration instructions tell you to set the unit into bypass mode & put a signal into the unit that shows 0dB on the meter, when adjusting q Bias.  It also looks like it should work on the original diagram, but I`m getting nothing ?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 03, 2004, 10:26:21 AM
Quote
Dean

Thats interestng because both sets of calibration instructions tell you to set the unit into bypass mode & put a signal into the unit that shows 0dB on the meter, when adjusting q Bias. It also looks like it should work on the original diagram, but I`m getting nothing ?
The G1176 has the meter grounded in Bypass mode. You'll need to use an external meter for Q-bias setup.

I did a little diagram a while back that gets meter function in bypass mode: http://www.home.earthlink.net/~deanp920/id1.html

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 03, 2004, 11:00:32 AM
Thanks Dean.

Its a bit weird that it cuts off in bypass , because it it works in by pass on my real 1176.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 03, 2004, 12:21:58 PM
Yes, but there's changed quite a lot around the metering/bypass in order to use a standard rotary switch, available anywhere..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 03, 2004, 08:39:12 PM
Jakob's meter switch design also excels in the fact that the VU meter is completely out of the circuit in bypass mode as well as GR mode.

For the purist wanting the G1176 as a line amp only, I've heard that this is a good thing. Apparantly the VU's rectifier sans buffer amp causes some distortion when placed in parallel with the audio path, although I have yet to hear it myself.

All in all, I decided not to use my meter mod. I just don't pay much attention to the meter. The thing is almost always in 'Nuke' mode, with the needle banging all over the place, or even in normal mode the meter is flying out of it's range by the time I get the kind of smooth pressed sound I like. For levels, I look at my DAW's input meters.

The Sifam makes a very impressive power indicator light, however. :grin:

Dean
Title: All things G1176 - the new "repost" thread.
Post by: salty on July 04, 2004, 06:58:22 PM
Quote from: "gyraf"
Salty,

Page1 in the G1176 layout .pdf has a description on how to mount the pots.

For the resistor in series with the release pot, are you thinking of using a potentiometer with integral switch?


Hi Jakob,

I never thought to download the .pdf file! Thanks.

Re. the switched resistor, I will be using a separate switch. Which pin is the correct one to use on the potentiometer?

Many thanks,

Nick Salt
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 05, 2004, 05:09:17 AM
Sorry more calibration questions !

If I disconnect the sifam meter I`m using from the circuit so that I can connect it to do the calibration.  Can I just put a 3k6 resistor in series with it & strap it across the output ?  Its just that if 0dB is is set on the meter to read the wrong level then the FET bias will be wrong.
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 07, 2004, 02:41:31 AM
Hi

almost ready for constuction. one question though.
how difficult would it be to adapt the G1176 ratio and meter controls to operate from the original push button switches?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 07, 2004, 06:22:08 AM
Hi Al,

No problem at all, if you can read the schematic, and find the right switches.

Just get the switches, and follow the original schematic..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 07, 2004, 03:20:58 PM
cool.

thanks Jakob. this has probably been asked before, but whats are the changes you made from the original design besides using the rotary switches?
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 07, 2004, 07:46:03 PM
DIY is as much about aesthetics to me as anything so I thought I'd put pushbutton switches on my disco-era silver face clone too. Somewhere in storage I had some interlocking switches but it was too much trouble to excavate them so I just used some cheap non-interlocking ones. Should make the slam mode easy.

I followed Jakob's lead and eliminated the +8 meter setting, putting the G.R. Disable there instead. I can post files if anyone wants - also, if anyone has a source for interlocking switches and can provide me with specs I'd be happy to modify my layout to handle these...
(http://img78.photobucket.com/albums/v295/mnats/1176_switches_meter.jpg)
More images:
Switch PCBs (http://img78.photobucket.com/albums/v295/mnats/1176_bank_switches.jpg)
Mounting Detail (http://img78.photobucket.com/albums/v295/mnats/1176_ratio_board.jpg)
*edited to insert smaller picture
*edited again because I put the wrong picture in
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 07, 2004, 09:59:59 PM
ahhh nice job mnats :thumb: . that's what i'm going for. once i get my switches i may ask you for some help. :green:
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 08, 2004, 06:43:52 AM
Mnats

Thats neatly done.  

I intend to do this, but in the UK its seems difficult to get the right sized buttons to put on the switches.  

No problem with the mechanisms

The latching mechanisms are not to difficult to get

RS part no 333-798 for a 4 switch mount and 333-625 for the latching bar (which is supplied in 10 switch lengths).
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 08, 2004, 09:01:36 AM
Rob,

Thanks. Check out the RS Australia prices for the switches:
Quote
Sold in multiples of 10     
          stock no.     price each     
    PCB mounting type           10-240     250-990     
   single     344-647     AUS$ 0.92     AUS$ 0.85     
    (April 2004 Catalogue page 1032)

Ok, not bad and I need at least 8. Now the latching bar:
 
Quote
Sold in multiples of 5     
          stock no.     price each     
                5-70     75-245     
   Latching bar     333-625     AUS$ 6.22     AUS$ 5.79     
    (April 2004 Catalogue page 1032)

Criminal! 5 latching bars = $31! No thanks. But it helps me understand how they can afford that big office on the main road.

Looks like an easy thing to carve out of a piece of metal though.

Buttons I used are here: http://www.altronics.com.au/cat.asp?cat=4&grp=238&id=H6630
...but they're ID .2mm too large for the RS ones. Damn.
Title: g1176
Post by: romeojesus on July 08, 2004, 04:57:18 PM
hi!

i am stuffing one of gustav´s g1176 pcb boards right now...

and i came across this:

shopping list says: 2x220p polyester

schematic and silkscreening on board say 200p!!

i guess it has got to be  200p´ s right??



one other thing:

one of the bc107b and one of the bc560  transistors and a 1N4003
maybe got a little hot accidentaly while soldering in...

replace on suspicion or go for it??



could´nt get a 500K trim pot!! I guess 470K is ok, is it?


thanks



christian
Title: g1176
Post by: romeojesus on July 08, 2004, 04:57:35 PM
hi!

i am stuffing one of gustav´s g1176 pcb boards right now...

and i came across this:

shopping list says: 2x220p polyester

schematic and silkscreening on board say 200p!!

i guess it has got to be  200p´ s right??



one other thing:

one of the bc107b and one of the bc560  transistors and a 1N4003
maybe got a little hot accidentaly while soldering in...

replace on suspicion or go for it??



could´nt get a 500K trim pot!! I guess 470K is ok, is it?


thanks



christian
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 09, 2004, 02:43:10 AM
QUOTE:

"200pF/220pF:
Jakob, i think i found a mistake in the part list of the G1176. In the schematic C3 and C4 are 200pf cabs. Also in the pcb layout. Now in the part list i only find 2x 220 pf instead of 2x 200pf
Flo,
Don't worry about that. Both will do fine, and 200pF is not easy to get at all.

Jakob E."


The quote above may be helpful. It was found on Orson Whitfield's site
which you can find in the "META THE 1176 PROJECT"

I would replace components if you feel you have over heated them with a
soldering iron severely. if you are trying to keep costs down and you want to take a chance and see if they are ok that should be fine. It depends on if feel you really toasted them good? I am not exactly sure how sensitive they are to the heat but if you dont feel you've heated them up that much they should be ok. I am not sure how they would affect the rest of the circuit if they were damaged? Sometimes bad components can damage others when you power up the unit. If you have the cash and
dont mind buying the extra components than do it.


The trim pot should be 470K the 500k may be easier to find. Nobody said that the 500K would be a problem so I am presuming it should work fine.


 :idea:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 09, 2004, 04:59:49 AM
Yep, 500k can easily be substituted for the 470K pot.

It's because in Europe we use the E3-range for pots (10-22-47) whereas in us and japan you use a 10-25-50-range

Pots are sloppy enough spec'd that these two ranges are essentially the same.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 09, 2004, 02:05:17 PM
Question about the placement/ orientation of the LORLIN switches
I purchased  for the Meter and Ratio for my 1176 project.

 I am not sure if anyone has already inquired about this?

 I have 2 small pcb's from Gustav. one if for the "Meter" switch
and the other is for the "Ratio" switch.

 I noticed the switches are labeled 1-12 (pins)

With the pcb in what I believe the normal orientation/position
how should the switch be orientated/placed in the holes?

Should it be: pin1 on left bottom/ pin 12 right bottom with pin 6
being top center. Or should the switch be placed into the pcb
orientated such as a wall clock with 12 being top center. :?
 :?:

Thankyou
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 09, 2004, 10:00:56 PM
Quote
With the pcb in what I believe the normal orientation/position
how should the switch be orientated/placed in the holes?


It will operate the same in either position.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 09, 2004, 11:04:13 PM
Thanks Rob!

 I have another Question. I have chosen to use The Lundahl
input Transfo rather than the 5532 IC. There are a few other
resistors and such in that circuit. Are there any other components
I can omit other than the 5532 if I will be using the Lundahl
on the input.

Thank you

 :wink:
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 10, 2004, 07:08:10 AM
Some might remember that I was working on a modified pcb board to try to eliminate the hum problems some people were having with this project without resorting to soldering a ground buss or wire across the board as had been suggested earlier. I also made it so either an OEP or Lundahl input or output transformer could be dropped in and changed it so the Lundahl output is reversed for increased gain and altered the output transistor pads so the BD135/136 could be fitted without twisting the leads.

Well, I'm nearly finished and have most of the wiring done and couldn't resist running a bit of audio through it. It works, it compresses but it's not calibrated yet. I think it's also fairly free of hum.

With the gain reduction disabled and the input and output pots at about 3/4 I ran a recording I made with around 5 seconds of silence then a door closing through my clone and fed the output into my mighty Sound Blaster Live! card.

Mp3 file is 151kB: 1176 test (http://users.bigpond.com/kmcilwain/files/1176test-1.mp3)
 
Sorry, it's not a very scientific test.
Title: All things G1176 - the new "repost" thread.
Post by: caps on July 10, 2004, 09:41:32 AM
Great work here Mnats. Is the comp actually in line and recorded in the first 5 seconds or did you just insert 5 secs silence? Reason being, is that I can hear practically nothing at all up until the door slam!! Which is a great thing btw. :0)
Title: All things G1176 - the new "repost" thread.
Post by: matthias on July 10, 2004, 10:14:29 AM
just a short question:


the 3pos meter switch has an out position...

ist that to bypass the conmpressor, or does it switch the meter off to prevent the slamming of the needle at heavy compression???


mat
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 10, 2004, 10:18:45 AM
It bypasses compression, just like turning down attack speed on the original.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 10, 2004, 03:38:48 PM
Quote from: "caps"
Is the comp actually in line and recorded in the first 5 seconds or did you just insert 5 secs silence?

Yes. That is, my clone is in line for the entire recording but on the original source I did add 5 seconds of silence. So you're hearing the entire audio chain up until the slam.

I've posted some additional info here (http://www.geocities.com/m_natsume/1176.html).
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 10, 2004, 09:13:21 PM
MNats

Have you had an opportunity to compare the Lundahl to the OEP transformer?
A friend & I did a comparison between Jakobs rev 7 with Lundahl output transformer but without input transformer to a pair of UREI rev H the otrher day.

The Lundahls are more toppy than the originals.   However they do compress in a similar way.  

Even with Chef`s rewiring of the transformer they lack a lot ofgain compared to the real things.
Title: All things G1176 - the new "repost" thread.
Post by: matthias on July 11, 2004, 10:48:52 AM
@ mnats:

very nice and informative page..  !!


is the lundahl output transformer connected in reverse on your pcb layouts, or is this not implemented yet...??


mat
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 11, 2004, 12:28:10 PM
Quote
Even with Chef`s rewiring of the transformer they lack a lot ofgain compared to the real things.


That mod does not get the output transformer configured for max output. With the Chef mod, you're still lacking 6 db of output gain AND headroom.

You need to go all the way and reverse the transformer so that you get a 1:2 step-up ratio. At that point everything pretty much falls in line with the original UREI specifications for maximum gain and headroom. If you use the optional input transformer, expect a small loss there(1 or 2 db) compared to the IC input.

The output impedance is  150 ohms in this reversed configuration, and will drive a 600 ohm load to the same levels as stated in the UREI manual. Frequency response remains ruler flat as well.

When I have a little more time I'll repost the instructions here. If someone has them saved from page 44 of the old thread, please feel free to go ahead and repost them here.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 11, 2004, 01:27:42 PM
Dean

Thanks for that info.  Are the 2 primary & 2 secondary windings both wired in series when reversing the transformer ?

I would like to have this extra gain, since I have found the 1176 quite useful to make up gain lost elsewhere in the signal chain.  In the current configuration when the out put is set to 1/2 o`clock on my real 1176`s I get the same gain as the G1176 on full output.

Are the 2 primary & 2 secondary windings both wired in series when reversing the transformer ?
Title: 1176
Post by: romeojesus on July 11, 2004, 02:59:02 PM
hi!

before finishing my g1176 a few more questions:

i am using the 5532 as input!

so i can leave out all the components marked with an *, right?

what about the 1000u/35 cap near the bd517?

(somewhere in this thread i read that putting this in gives me lower noise! so i guess it´s optional, but has nothing to do with the
optional lundahl inout trafo??)

what connections between the boards should be shielded?
where do i ground the shields??


thanks

christian
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 11, 2004, 06:00:19 PM
The wife wants a new gate for the side of the house so it's chiselling mortises and sawing tenons for the next couple of days...

Quote
Have you had an opportunity to compare the Lundahl to the OEP transformer?

No, but I do intend to try this at a later date. My understanding is that the Lundahls are less colored.
Quote
Even with Chef`s rewiring of the transformer they lack a lot ofgain compared to the real things.

I didn't use the Chef mod which seems to involve paralleling the input windings but rather the one suggested by Jakob which involves reversing the transformer but keeping both windings wired in series.
Quote
is the lundahl output transformer connected in reverse on your pcb layouts, or is this not implemented yet...??

Yes, it's definitely reversed on my pcb. This was one of the main reasons I bothered to make a new version. Because the Lundahl isn't symmetrical you can't just rotate it on the board so you either have to cut traces and use wires or use my layout. I have also posted another version that uses the original output transistors since many people have access to these devices but want/need the other mods.
Quote
Are there any other components I can omit other than the 5532 if I will be using the Lundahl on the input.

Look at the schematic in the upper left hand corner. Eliminate everything to the left of R5, the input pot. Looks like the input pot itself is still being used on the Gyraf rather than a T attenuator on the UREI. The components are marked with the original component identifications on my .pdf layout file so you may want to download these to have a clearer idea of which parts to leave off (Gyraf .pdf mostly has component values). That part of my board is nearly identical so it should be clear which components to pull.
Quote
so i can leave out all the components marked with an *, right?

I think the parts marked * on Jakob's layout are mostly the optional bypass and filtering capacitors. They don't directly relate to using the opamp or transformer input issue. The two 10k resistors marked * can be left off if using the opamp.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 11, 2004, 06:18:45 PM
Rob,
Quote
Are the 2 primary & 2 secondary windings both wired in series when reversing the transformer ?


Yes, they are. Just make sure you get the polarity right(you don't want phase reversal along with the extra gain), as well as leaving pin 3(can+core) grounded.


Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 11, 2004, 07:24:31 PM
Thanks Dean

I`ll give it a try tomorrow.
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 12, 2004, 10:55:26 AM
found it...

Quote from: "deanp920"
If you want to try it 1:2, in and out connections should be reversed - by cutting tracks and soldering on some wires..
On the primary, pin 4 should be isolated from the ground plane by cutting the wide ground trace with a dremel tool or utility knife.

The trace connecting C15 to pin 1 must be cut.

On the secondary, pins 6 and 9 need to be isolated by cutting the traces near the pins.

Solder a jumper wire from pin 4 to the solder pad for point Y.

Solder a jumper wire from pin 1 to the solder pad for point X.

Solder a jumper wire from pin 9 to the solder pad for the negative side (output) of C15.

Solder a jumper wire from pin 6 to pin 3.

That should leave the transformer running 1:2, and increase in the signal line amp's gain by 12db.

For what its' worth, I measured the transformer's output impedance, wired stock (2:1), at about 30 ohms. This is encouraging, since, when wired 1:2, the output impedance should still be well under 600 ohms.

EDIT 4-12-04 Instructions above no longer cause phase reversal.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 12, 2004, 11:46:23 AM
Thanks Mnats & Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 12, 2004, 12:27:58 PM
Just tried the mod, it works but I`m not getting the 12dB increase.  I`m only getting about +4dB ?  Any ideas ?


The instructions are not quite right as far as I can tell.  I think pins 6 & 9 should be connected but ther is only mention of osolating them in the instrctions.

Mnats I notice on your board this mod is carried out in a slightly different way t o the instructions above.
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 12, 2004, 12:43:32 PM
Quote
I think pins 6 & 9 should be connected but ther is only mention of isolating them in the instrctions.

Quote
[/i]


Sorry I think I meant pins 7 & 10
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 12, 2004, 05:37:03 PM
Quote
The instructions are not quite right as far as I can tell. I think pins 6 & 9 should be connected but ther is only mention of osolating them in the instrctions.


The instructions are correct.

Pins 7&10 are not mentioned, as they stay connected with the existing trace. Same with pins 2&5.

Pins 6&9 MUST be isolated so pin 6 can be grounded, and pin 9 driven from C15 like the procedure states. That converts the secondary of the 5402 into the primary.

Pins 1&4 are isolated and then jumpered to the x and y points, respectively. That converts the primary of the 5402 into the secondary.

Now you have a 12db increase in output from the stock PCB.

Simple. :grin:

Dean
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 12, 2004, 05:47:31 PM
Quote
Mnats I notice on your board this mod is carried out in a slightly different way t o the instructions above.

Still a bit bleary-eyed. Damn cold I caught has woken me up again with a cough...anyway, as I recall when I did my board it was just convenient to wire the transformer mirror-imaged from the Dean mod. Doing it that way allowed the OEP pinout to nest there without wire jumpers running all over the place.
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 12, 2004, 06:49:58 PM
Mnats

Your layout looks good.  I`m getting a friend to make me a pair of boards so I can do some with the OEP tansformers.
Title: All things G1176 - the new "repost" thread.
Post by: mik on July 13, 2004, 05:34:52 PM
I've cecked the Mnats layout, it's seems to everything it's ok but the Lundhal out trafo dimension missmatch to the original: they are 2mm smoler , 28mm instead 30 so It will difficout to fitt a lundhal there.
second:
for macth a correct Eurocard dimensio it should be little bit smoler more similar  dimension to the Jako's design , this because fotoresit is not so good close to the adge of the board, so the pads can go really bad, even using a good quality boards.
Thank you Mnats for your job
mik :sam:
P.s.
I'm anxiusly waiting for the correct one 'cause I really need  it!
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 13, 2004, 11:20:47 PM
mik,

Thank you for checking the layout -  I really appreciate it. You're right, the pads were .1" short of their correct location. I've fixed the files and uploaded them to my site.

I didn't know the resist was poor at the board edges with the Eurocards. The overall dimensions of the board is identical; I'll try to pull the traces and pads away from the edges but I don't think it will be easy or as quick as fixing the Lundahl problem.

Thanks again for pointing out the problems.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 14, 2004, 03:04:31 PM
Jakob, Dean,

     The VU is acting as it should now!   :thumb:  :green:  :sam:  And no more huge gain increase when the ratio switch is set to 1:20.:guinness:  :!:  :grin:
I am calibrating and I notice the output is always a 1/3 lower than input no matter how I attenuate the input volume from my audio generator.  THis didn't happen before.  BTW,  the part that was wrong was the 10M resistor at the top of the ratio switch PCB. Anyhow,  what's going on that I can't get the GR meter track calibrated?
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 14, 2004, 03:22:27 PM
Ok, I'm troubleshooting the second of a pair of 1176's, and am getting to the stumped part, so thought I would post for suggestions.

It's not passing audio yet ( the other works fine, dammit =) ).

At present the problem is in the signal pre-amp section.  The voltages are not right, and I can't figure out why.  Have gone through looking for shorts, and have checked out the parts values to make sure they are correct.  Here's what I got:

The voltage comin off the regulator is right on at 30.3, but post R17 (6.8K), I'm down a couple volts from what should be 25.8, I'm sittin at 23.4V.

so by the time I start measuring voltage at Q2 and Q4, things are not good.

Q4:

E 1.3  (11.5)
B 1.9  (11.9)
C 30.3 (30.3 )

Q2:
E 0  (.5)
B 0 (1.02)
C 2.5V (1.76)

Thoughts?  I'm pulling out the hair I don't have  :?

ju
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 14, 2004, 07:24:19 PM
Ok, found the problem and fixed it.  was a short between two pins of Q3.

Even tho it didn't look shorted, it was =).  I found it by measuring resistance across the resistors, and in this case, the 560K resistor near Q3 was reading 2K.  I started removing components that connected via trace to this resistor, and I'd removed all but Q3.  Once I continuity checked the pins of Q3, I found the short.  Nothin an exacto knife can't fix.

Trackin drums with a pair of 1176's tomorrow  :!:  :green:   Thanks for the project Jakob :!:  :!:  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 15, 2004, 04:21:43 AM
Ju,

That is good news. Let us know how it turns oyt..

Orson,

Remember to recalibrate the "Q-Bias", now that you fixed the rest of the circuit..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 15, 2004, 11:09:49 AM
I did that already,  Jakob.  Whats happening is that I can't get the GR meter tracking calibrated because the output is always 1/3rd the voltage of the input no matter what I do.  Something's up but what?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 15, 2004, 07:23:10 PM
Hey Orson,

Put a known signal level, like 50mV 200Hz on the input XLR(measure across pins 2&3 and ground pin 3 with a clip lead if you signal generator is unbalanced).

Crank the input and output knobs(unit in bypass).

Measure signal level from the input wiper to ground.

" " output wiper to ground

" " across pins 2&3 of the output XLR(no need to ground pin 3)

Let's start there.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 15, 2004, 07:46:21 PM
Quote from: "deanp920"
Put a known signal level, like 50mV 200Hz on the input XLR(measure across pins 2&3 and ground pin 3 with a clip lead if you signal generator is unbalanced).
Done. 49.9mV @200hZ from SG and 49.9mV measures across pins 2&3. Pin 3 grounded to pin 1.

Quote from: "deanp920"
Crank the input and output knobs(unit in bypass).


Quote from: "deanp920"
Measure signal level from the input wiper to ground.
it measures 49.7mV.

Quote from: "deanp920"
" " output wiper to ground
it measures 227.4 mV.

Quote from: "deanp920"
" " across pins 2&3 of the output XLR(no need to ground pin 3)Dean
It measures 1.402 V.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 15, 2004, 11:03:03 PM
Orson,

Only the input XLR and input wiper look right.

Bear with me and pull Q1 BF245A and repeat the measurements.

Also measure from ground to the transformer side of C15. Is the output transformer stock or modded? If so, what mod(mine or Chef's)?

Gain is way low in both the signal pre amp and signal line amp.

Let's try to find the cause.

I'm going to put mine under the same test conditions tomorrow evening so we can compare directly.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 16, 2004, 01:02:10 AM
ok  here we go again.

Removed Q1 BF245.

50mV input from signal generator @ 200 hZ.
input XLR pin 2 and 3 with one tied to three is 50.mV.

I crank full CW input and output knobs and place unit in bypass mode.

Signal input from input wiper to ground is 50 mV.


output wiper to ground measures 1.073 V.

output XLR across pins 2 and 3 (no grounding on pin 3) measures 6.73V.

So there is a difference with the BF245 removed.  I have done the CHEF mod on mine.  I believe it's Chef's - where I had to cut traces and wire places together.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 16, 2004, 07:37:04 AM
Orson,
Quote
Also measure from ground to the transformer side of C15.


We still need that measurement. That helps take the OPT out of the equation.

Signal preamp gain looks correct now.  Signal line amp is probably alright, if you did the 1:1 mod by Swedish Chef. Go back and find out what you did for certain. If you did my 1:2 mod you have an error.

Sounds like something is wrong with your Qbias supply and/or compressor side chain circuit.

I need to think about this some more.

We're getting closer.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 16, 2004, 10:16:14 AM
Quote from: "deanp920"
Also measure from ground to the transformer side of C15. Is the output transformer stock or modded? If so, what mod(mine or Chef's)?
Dean


3.783 V from ground to  the transformer side of C15.  Sorry I left that one out before.  I know your mod was changing a resistor but I cut traces on the pcb so it must have been Chefs mod.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 16, 2004, 06:58:28 PM
Hello,

 I have 2 torroid transformers I have purchased from AVEL LINDBERG
p/n Y236106 they are :

30VA Load rated

25+25 secondary voltage


I hooked up the primary with 122VAC and I am getting

30+30vac output  :shock:


Their p/n Y236107 is a 30VA 30+30 unit.
I am thinking that they mis labeled these?
How would it affect the 1176 unit if I were
to use these with 30vac rather than 24vac?

any comments/suggestions welcome
I emailed the company that makes these a week
ago and they have not yet responded.  :roll:


Thanks!
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 16, 2004, 08:02:54 PM
Are you just connecting only your meter to the secondaries ?

If so you would expect the reading to be high.   If the transformers secondaries are loaded. i.e they are supplying the circuit these readings would drop.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 16, 2004, 08:14:27 PM
Thanks rob.. I had this on my mind when I posted.

Yes..just the "Fluke" meter unloaded.

 I was wondering how much the voltage would drop when loaded?

 I guess I could break out the old calculator and try to do some math
to figure what it might be under load. I don't think the 1176 draws much?

Hopfully when loaded down it will drop to approx 24 vac

thanks again  :wink:
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on July 16, 2004, 08:33:23 PM
Even if the output voltage was a bit higher than 25v it shouldn`t be a problem since the 7824 regulator & zener for the -10v are "fairly" flexible to input volatge changes
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 17, 2004, 02:19:25 AM
Orson,

Quote
I know your mod was changing a resistor but I cut traces on the pcb so it must have been Chefs mod.


We need to straighten this out.

I did a mod that involved changing a resistor. It works fine, but instead I implemented a transformer mod suggested by Jakob that involved cutting traces on the PCB and adding jumpers to get a ~1:2 step-up ratio. This is the mod I currently am using and also the one I'm pretty sure you are using also. I posted earlier that I thought you had either the Chef 1:1 mod an error with my 1:2 mod, but I see now that I was wrong.  
 The instructions are a page or two back on this thread reposted by mnats.

The Chef mod involves trace cutting and jumpering as well, but creates an ~1:1 output ratio. Instructions for this mod were posted by Swedish Chef on the More Gain for G1176 thread from the old forum.


OK, I set my G1176 up just like yours with the Q1 pulled and a 50mV, 200Hz input signal. Input and Output cranked. Unit set to bypass.

Input wiper: 50mV

Output wiper: 1V

C15 transformer side: 3.8V

Output XLR: 6.8V

Now I put the FET back in and I get...

Input wiper: 50mV

Output wiper: .96V

C15 transformer side: 3.4V

Output XLR: 6.13V

So, with Q1 pulled we have nearly the same gain figures; roughly 43db overall.  :cool:  :grin:

But with Q1 reinstalled my gain only falls to 42db, where yours falls to 29db. :?

Furthermore, you are losing it all in the signal preamp stage. This confirms that Q1 is either damaged or starved for negative bias voltage.

With no signal applied, I/O max, Attack and Release max, Ratio 20:1, Bypass mode, I get about -2.2Vdc from ground to any pin on the release pot. The reading is the same whether Q1 is in or out of it's socket.

Check this voltage and let us know the results.

Hang in there, Orson!

Dean
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 17, 2004, 07:41:28 AM
Good work here Dean!

 :thumb:

It should be noted that the voltage at the release pot is adjusted with the "Q-Bias" trimmer. So it would make sense to know what the voltages at the release pot is for both end adjustments of the Q-Bias-trimmer..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 17, 2004, 12:26:57 PM
Quote
It should be noted that the voltage at the release pot is adjusted with the "Q-Bias" trimmer. So it would make sense to know what the voltages at the release pot is for both end adjustments of the Q-Bias-trimmer..

Jakob E.

Right! :grin:

A good, specific reference seems to be putting the release pot at minimum and measuring from the wiper to ground. This is electrically the same point as the Qbias trimpot's wiper, but easier to get at, at least for me.  

So, with the release pot at minimum and measuring from its' wiper to ground, I get -2.88Vdc at one extreme of the Qbias trimmer's rotation. At the other extreme of the Qbias trimmer's rotation I get 0Vdc.

What do you measure, Orson?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 17, 2004, 09:16:03 PM
Okay.  Here below is the mod I found back a few pages.  After i double checked what I did I found a discouraging thing.  I did everything as this mod said to do but I soldered a jumper from 4 to the solder pad for point X instead of Y and from 1 to the pad of Y instead of X.   :roll:  Now I am in a rush to gig tonite so i don't have time to look for the more gain thread that lists the other Mod. So we have done the same mod Dean?  I thought I remembered we didn't - oh well I don't trust my memory anway. :?   Well if the other mod is not simply reversing the Y and X  jumpers then this is the mod I did with error.  Abit Omen!  I remember triple checking this before I did it.  I can't believe I made this mistake.  I'll measure the voltages you said to do Dean and I 'll post them tomorrow.  Thank you for the continued help. Oh and by the way,  while measuring voltages my DMM lead moved the Q1 BF245 a little in the socket.  Perhaps that fried it? You mentioned it might be so i thought I'd throw that in.
Quote from: "mnats"
found it...

Quote from: "deanp920"
If you want to try it 1:2, in and out connections should be reversed - by cutting tracks and soldering on some wires..
On the primary, pin 4 should be isolated from the ground plane by cutting the wide ground trace with a dremel tool or utility knife.

The trace connecting C15 to pin 1 must be cut.

On the secondary, pins 6 and 9 need to be isolated by cutting the traces near the pins.

Solder a jumper wire from pin 4 to the solder pad for point Y.

Solder a jumper wire from pin 1 to the solder pad for point X.

Solder a jumper wire from pin 9 to the solder pad for the negative side (output) of C15.

Solder a jumper wire from pin 6 to pin 3.

That should leave the transformer running 1:2, and increase in the signal line amp's gain by 12db.

For what its' worth, I measured the transformer's output impedance, wired stock (2:1), at about 30 ohms. This is encouraging, since, when wired 1:2, the output impedance should still be well under 600 ohms.

EDIT 4-12-04 Instructions above no longer cause phase reversal.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 18, 2004, 05:10:03 AM
Hi Orson,
Quote
After i double checked what I did I found a discouraging thing. I did everything as this mod said to do but I soldered a jumper from 4 to the solder pad for point X instead of Y and from 1 to the pad of Y instead of X.  
No worries whatsoever. That just causes phase reversal of the output signal; make the correction and all should be well.
Quote
So we have done the same mod Dean?
Yes, we have. Once you fix the little x/y error, you're fine; leave it be.

Make sure you read my posts one page back on this thread that outline the fact that our gain blocks sans Q1 match up perfectly. We just need to figure out why your Q1 is clamping down so hard at idle.
Quote
Now I am in a rush to gig tonite so i don't have time to look for the more gain thread that lists the other Mod.
Don't bother right now. What you have done already is probably about as good as it gets and also puts us both on the same page.
Quote
Oh and by the way, while measuring voltages my DMM lead moved the Q1 BF245 a little in the socket. Perhaps that fried it?
I doubt it, but we'll soon find out I hope.
Quote
I'll measure the voltages you said to do Dean and I 'll post them tomorrow.
Yeah, let's pick up there and see if we can chase down the problem.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 18, 2004, 03:09:45 PM
Quote from: "deanp920"
OK, I set my G1176 up just like yours with the Q1 pulled and a 50mV, 200Hz input signal. Input and Output cranked. Unit set to bypass.

Ok I have this exact setup now.
Quote from: "deanp920"
Input wiper: 50mV
I have 50mV.
Quote from: "deanp920"
Output wiper: 1V
I have 1V.
Quote from: "deanp920"
C15 transformer side: 3.8V
I have 3.73V
Quote from: "deanp920"
Output XLR: 6.8V
I have 3.248V :!:
Quote from: "deanp920"
Now I put the FET back in and I get...
Input wiper: 50mV
I get 50mV
Quote from: "deanp920"
Output wiper: .96V
I measure 1V.
Quote from: "deanp920"
C15 transformer side: 3.4V
I have 3.72V.
Quote from: "deanp920"
Output XLR: 6.13V
I have 3.248  :!:
Quote from: "deanp920"
So, with Q1 pulled we have nearly the same gain figures; roughly 43db overall.  :cool:  :grin:
But with Q1 reinstalled my gain only falls to 42db, where yours falls to 29db. :? Furthermore, you are losing it all in the signal preamp stage. This confirms that Q1 is either damaged or starved for negative bias voltage.
With no signal applied, I/O max, Attack and Release max, Ratio 20:1, Bypass mode, I get about -2.2Vdc from ground to any pin on the release pot. The reading is the same whether Q1 is in or out of it's socket.
I get 2.4Vdc with it in and 2.8Vdc withit out.   :!:
I hope I haven't left anything out for testing.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 18, 2004, 08:32:02 PM
Dean, please read my post right before this one incase you missed it.
Quote from: "deanp920"
Quote
It should be noted that the voltage at the release pot is adjusted with the "Q-Bias" trimmer. So it would make sense to know what the voltages at the release pot is for both end adjustments of the Q-Bias-trimmer..

Jakob E.

Right! :grin:

A good, specific reference seems to be putting the release pot at minimum and measuring from the wiper to ground. This is electrically the same point as the Qbias trimpot's wiper, but easier to get at, at least for me.  

So, with the release pot at minimum and measuring from its' wiper to ground, I get -2.88Vdc at one extreme of the Qbias trimmer's rotation. At the other extreme of the Qbias trimmer's rotation I get 0Vdc.

What do you measure, Orson?

Dean

I forgot to rotate the trimmer for the "Q-bias" the other way around to see the differnece.  So,  here is the result of that test:

OK I get -1.5 dc mV with the trimmer all the way cw and the release knob set to full CW.  I assumed that this is the "minimum" setting you meant?  Well, anyway,  thats what I did.  And now the result with the Q-bias trimmer all the way CCW and the release knob still set full cw: -2.504 dc V
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 18, 2004, 08:58:04 PM
Orson,

You must have just changed something for the worse on your output transformer. You JUST had 6.8V(previous page) on the output XLR with the FET pulled and now you have 3.2V.

Go back and see what you just did to that output transformer!

What is good to see is that things are looking much better gain-wise when you put the FET back in(maybe something wasn't seated before, or the Qbias trimmer was set way wrong). Everything in terms of gain stays about the same, which is good, except you need to fix your OPT so it works like it did before.

That dc voltage on the release wiper should be a NEGATIVE number(black probe to ground). Go back and verify that. While you are measuring there, run the Qbias trimmer from one extreme to the other, note the voltage at each extreme, and leave it set for the highest negative voltage(should be better than -2Vdc).

The idea will be to reduce this negative voltage just a a tad with the Qbias trimpot until the output falls just 1db. This puts Q1 right at the beginning of its conduction.

But leave the Qbias trimpot at max bias for now and get that OPT sorted out so you get back your ~6.8V with the FET installed. Just back up and carefully go through your OPT wiring and hopefully you'll find the error. Power down and use your ohmeter to verify jumper connections and trace cuts, if needed.

If you are confused, let us know. I think we're close. Just stay focused and bear with me a little more.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 18, 2004, 09:03:06 PM
Quote
OK I get -1.5 dc mV with the trimmer all the way cw and the release knob set to full CW. I assumed that this is the "minimum" setting you meant? Well, anyway, thats what I did. And now the result with the Q-bias trimmer all the way CCW and the release knob still set full cw: -2.504 dc V
No, I meant full CCW on the release pot; sorry. What you have looks great, though, considering you have the release pot full CW.

Check my previous post(I was writing it when you posted last) and come on back.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 18, 2004, 10:18:16 PM
Ok this is not my last post tonight.  I have checked ten times what i have done and according to what I see on the PCB diagram i have correctly wires the output tranny.  And yes I have a lower Voltage than beofre.  Maybe a cable got loose somewhere let me check OR someone typed the instructions for the mod incorrectly.  Are you sure this is correct the way it is printed on the quote I presented on this page of the thread?
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 18, 2004, 10:55:14 PM
Quote from: "deanp920"
Orson,

You must have just changed something for the worse on your output transformer. You JUST had 6.8V(previous page) on the output XLR with the FET pulled and now you have 3.2V.
OK  It was my fault I was measuring star ground instead of pin 3! That's why I got a different voltage reading.  Now I have to change the output tranny jumpers back to the new, correct placement and make sure I still have the higher voltage measurement on pins 2 and 3.  Sorry about this mix up> I did not know ground was different than pin 3.


Quote from: "deanp920"
What is good to see is that things are looking much better gain-wise when you put the FET back in(maybe something wasn't seated before, or the Qbias trimmer was set way wrong).
This is VERY possible.  Especially since there are things I have been measuring using AC on my DMM instead of DC.  I just didn't know this.  Sorry.  And it's very possible Q1 was not seated correctly.  I did let the leads from the DMM brush by the Q1 once.
Quote from: "deanp920"
That dc voltage on the release wiper should be a NEGATIVE number(black probe to ground). Go back and verify that.
Yeah it was negative I didn't tell you and I should have been specific.  i see that there is a difference between the two now.
Quote from: "deanp920"
While you are measuring there, run the Qbias trimmer from one extreme to the other, note the voltage at each extreme, and leave it set for the highest negative voltage(should be better than -2Vdc).
The idea will be to reduce this negative voltage just a a tad with the Qbias trimpot until the output falls just 1db. This puts Q1 right at the beginning of its conduction.
You see,  here is a prime example of what's been going wrong for me if what you have posted here is a reiteration of what the Q-Bias calibration setup is. If so,   I have been measuring this in AC not DC, as I should have.  Well,  the good news is all this has taught me a lot and shown me that I had my tranny Jumpered incorrectly.  This is good stuff.

Quote from: "deanp920"
But leave the Qbias trimpot at max bias for now and get that OPT sorted out so you get back your ~6.8V with the FET installed. ... Power down and use your ohmeter to verify jumper connections and trace cuts, if needed.
I don't know what exactly to do to check the resistence (sp?) with my DMM ohmeter section, so let me just put that out there right at the start before i go measuring things incorrectly again.  In the mean time I'll put the jumpers to where they should ne and follow your new directions and post the results.  Sorry for the long posts.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 18, 2004, 11:15:24 PM
OK  changed the jumpers back to the correct position (4 to Y and 1 to X).
Quote from: "deanp920"
You must have just changed something for the worse on your output transformer. You JUST had 6.8V(previous page) on the output XLR with the FET pulled and now you have 3.2V.
OK now I have measured 6.49V.


Quote from: "deanp920"
That dc voltage on the release wiper should be a NEGATIVE number(black probe to ground). Go back and verify that. While you are measuring there, run the Qbias trimmer from one extreme to the other, note the voltage at each extreme, and leave it set for the highest negative voltage(should be better than -2Vdc).
It is .  I have -2.041 dc V.


Ok my brain is getting fried. What do i need to measure now?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 18, 2004, 11:53:02 PM
Orson
Quote
Ok my brain is getting fried. What do i need to measure now?
OK, I'm ready to call it a night.

At this point you can turn the Qbias pot the other way until that 6.49Vac drops to something like 6Vac. I can't find my calculator right now, but you're looking for a ~1db drop. That sets your Qbias.

The compressor should be working correctly now, with the exception of the meter, which is ready to be calibrated.

Let me know where you're at. :grin:

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 18, 2004, 11:57:10 PM
One thing I need clarification on is wether or not the values are supposed to be similar with the Q1 removed and when it's present?  I get different dc voltages on the release pot with it removed and with it present.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 19, 2004, 07:53:28 AM
Quote
One thing I need clarification on is wether or not the values are supposed to be similar with the Q1 removed and when it's present? I get different dc voltages on the release pot with it removed and with it present.
I'm assuming you are referring to the negative voltage measured off the wiper of the release pot from ground. No, that should not change one bit when the FET is removed. Only the signal level at the output XLR should fall a bit.

What Vdc are you getting on the wiper of the release pot under these circumstances:

Release full CCW FET in

Release full CCW FET out

Release full CW FET in

Release full CCW FET out

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 19, 2004, 01:03:28 PM
Quote from: "deanp920"
Quote
One thing I need clarification on is wether or not the values are supposed to be similar with the Q1 removed and when it's present? I get different dc voltages on the release pot with it removed and with it present.
I'm assuming you are referring to the negative voltage measured off the wiper of the release pot from ground. No, that should not change one bit when the FET is removed. Only the signal level at the output XLR should fall a bit.
Mine does change dramatically.  I get a -.816 dc V with it in and -2dc V with it out.

Quote from: "deanp920"
What Vdc are you getting on the wiper of the release pot under these circumstances:

Release full CCW FET in
0.816dc V

Quote from: "deanp920"
Release full CCW FET out
-2.026dc V

Quote from: "deanp920"
Release full CW FET in
-2.513dc V.

Quote from: "deanp920"
Release full CCW FET out
I assume you meant CW here? If so I get -2.799dc V.

Also, remember I could not get the GR meter Tracking set because my xlr output voltage was always a 1/3 of the input voltage no matter how much or little I attenuated the input to the input xlr from the sound generator.  According to the instructions for calibration,  step four is to get unity gain and then turn up the input signal at the source until you reach a point where the output level is half the input.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 19, 2004, 09:39:46 PM
Ok, here are my numbers measuring from the release pot wiper to ground:

Release pot full CCW FET in: -2.22Vdc
                               FET out: -2.22Vdc

Release pot full CW FET in: -2.15Vdc
                             FET out: -2.15Vdc

The first thing that bothers me is that you get more negative bias with the release pot full CW, and you I more with it full CCW. Double check the wiring on your release pot, as well as verifying its' component value.

Make sure you have the pins of your FET oriented correctly.The shape of the FET should match up with the overlay on the PCB.

If you still haven't found an error, try another FET.

Lastly, try another FET in the Q10 socket and also verify its' orientation.

I very much suspect that you have a wiring or component error somwhere in the electronic vicinity of Q1.

Try these suggestions and I'll think some more about this.

In the meantime, your project should sound good as a line amp with tons of gain. Just leave Q1 out. It would be nice at this point to verify your project's functionality in this capacity.

We'll get it!

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 20, 2004, 05:56:51 PM
Which pot wiper do I use,  Dean?  Because the bottom one gives me  -2.09 dc V with FET in or out and with the release pot set to full CW or full CCW.  I thought I was supposed to use to top one.  I think I am measuring incorrectly. I have the FET set in correctly.  

The unit is passing audio and does have much gain.  I don't know if it's working correctly.  When I measure the output XLR I use the red lead on the#2 pin but do I use the black lead on pin #1, pin#3 or star ground?  Each one gives me a different measurement.  I still have pins #1 and #3 connected on the input XLR and not connected on the ouput XLR.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 20, 2004, 06:47:13 PM
Quote
Which pot wiper do I use, Dean?
There is only one wiper, and it is almost always the center contact. It corresponds to the arrow you see on the schematic. The other two contacts are each end of the resistor, commonly referred to as the high and low sides. I should have been more specific.

Repeat the measurements using the center contact and ground and let me know what you get. Then we'll be caught up. Go ahead and try a new FET while you're at it if things still seem wrong compared to my figures. Your negative voltage may read a bit higher, since your Qbias pot is at max and mine is set back already. It's the differences in voltage that are of concern here. Pulling the FET should do nothing; turning the release pot back and forth should only cause a slight change(.05V or so). If it still seems screwed up, change both FET's(Q1&Q10) and see if that helps.

Also, with the release pot full ccw, briefly turn the Qbias pot to its' other extreme; you should read 0Vdc. Then put the Qbias trimmer back where it was. If the release pot needs to be full cw to read 0Vdc, then you have the two outer wires on the release pot mixed up, assuming you have the center contact wired correctly. Check it out.
Quote
The unit is passing audio and does have much gain.
That's good. Is that with the FET out?
Quote
When I measure the output XLR I use the red lead on the#2 pin but do I use the black lead on pin #1, pin#3 or star ground? Each one gives me a different measurement. I still have pins #1 and #3 connected on the input XLR and not connected on the ouput XLR.
Measure across pins 2&3. For an AC measurement, probe polarity does not matter.

You may use pin 1 or star ground only if either pins 2 or 3 are grounded also, which makes the output single ended, or unbalanced. Pin 1 should be grounded. Measure across output XLR pins 2&3 only and you'll be OK.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 20, 2004, 09:09:28 PM
Quote from: "deanp920"

Repeat the measurements using the center contact and ground and let me know what you get.
  will do. see below.    

Quote from: "deanp920"
Go ahead and try a new FET while you're at it if things still seem wrong compared to my figures. Your negative voltage may read a bit higher, since your Qbias pot is at max and mine is set back already. It's the differences in voltage that are of concern here. Pulling the FET should do nothing; turning the release pot back and forth should only cause a slight change(.05V or so). If it still seems screwed up, change both FET's(Q1&Q10) and see if that helps.
see below,  it's looking good.

Quote from: "deanp920"
Also, with the release pot full ccw, briefly turn the Qbias pot to its' other extreme; you should read 0Vdc. Then put the Qbias trimmer back where it was. If the release pot needs to be full cw to read 0Vdc, then you have the two outer wires on the release pot mixed up, assuming you have the center contact wired correctly. Check it out.
I get  -000.9 mV.   I guess that's close enough to 0Vdc.  


Quote from: "deanp920"
Quote:
The unit is passing audio and does have much gain.
That's good. Is that with the FET out?
it passes audio with the FET in and out.  It does get louder with it out though.

Quote from: "deanp920"
.... Measure across output XLR pins 2&3 only and you'll be OK.
I did this this time - makes a difference :cool:



Quote from: "deanp920"
OK, I set my G1176 up just like yours with the Q1 pulled and a 50 mV, 200Hz input signal. Input and Output cranked. Unit set to bypass.

Ok I have this exact setup now except 49.8 mV is the closest I could get to 50 this time..
Quote from: "deanp920"
Input wiper: 50mV
I have 49.6mV.
Quote from: "deanp920"
Output wiper: 1V
I have 1.059V.
Quote from: "deanp920"
C15 transformer side: 3.8V
I skipped this one.
Quote from: "deanp920"
Output XLR: 6.8V
I have 6.63V  :grin:
Quote from: "deanp920"
Now I put the FET back in and I get...
Input wiper: 50mV
I get 49.6 mV
Quote from: "deanp920"
Output wiper: .96V
I measure 1.059V with the q - biad trimmer all the way to one side.
Quote from: "deanp920"
C15 transformer side: 3.4V
I skipped this one.
Quote from: "deanp920"
Output XLR: 6.13V
I have 6.63 V

Quote from: "deanp920"
With no signal applied, I/O max, Attack and Release max, Ratio 20:1, Bypass mode, I get about -2.2Vdc from ground to any pin on the release pot. The reading is the same whether Q1 is in or out of it's socket.
I get -2.806 Vdc with it in and out.  :grin:

Are things looking good. :?
Title: All things G1176 - the new "repost" thread.
Post by: soundguy on July 20, 2004, 09:11:33 PM
dont know if this was in the 58 page old post or not, but Im just building a rotary switch for an old 1176 and looking at the nuke mod for the gyraf switch, couldnt you just program the lorlin for 5 positions, wire a jumper from 1-5, 4-5, 7-11, 10-11 and get your "all in" position as the fifth position on the switch?  This would save you adding a dpdt if it works...

Is my thinking right here?

dave
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 20, 2004, 10:09:55 PM
Quote
dont know if this was in the 58 page old post or not, but Im just building a rotary switch for an old 1176 and looking at the nuke mod for the gyraf switch, couldnt you just program the lorlin for 5 positions, wire a jumper from 1-5, 4-5, 7-11, 10-11 and get your "all in" position as the fifth position on the switch? This would save you adding a dpdt if it works...

Is my thinking right here?



Dave, I can't remember anyone trying that, but it is pretty hard for me to visualize right away. There sure are a lot of different ways to skin a cat with those rotary switches; the possibilities are incredible.

Please pursue this and let us know if it works; I don't doubt that it might.

OK Orson,

From your last post things are looking very good. I don't quite understand how you are hearing a level shift with the FET in or out when the output measures exactly the same whether the FET is in or out. I'll assume a minor miscommunication and leave it at that unless you think otherwise.

The next thing to do is back off the Qbias pot while monitoring the output XLR until the output drops a very little bit(about 1db; use the formula), say to about 6Vac. That sets the Qbias. Hopefully you will turn the pot a bit before the output starts to drop; that just shows that you are truly approaching the cutoff point and not already past it even with the Qbias pot at max.

Then you can go ahead with the meter calibration procedure. Stick with the 200Hz frequency, though, so you can make accurate AC measurements with your DMM. It is really handy to use a meter on the input and another meter on the output so you can monitor things simultaneously.

Take your time and let us know how its going. Ask all the questions you need to.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 20, 2004, 10:35:17 PM
OK All is done and calibrated.  It sounds good.  I guess it's working.  Perhaps, in my mind I was imagining a different, more "in your face" compression from the 1176.  But instead it sounds gentle.  That is ofcourse if this is working right but i guess it is.  The last problem is the intermitent crackling.  It comes and goes but always doesn't start happening until the unit has been powered on for thirty minutes.  The crakiling is not constant or the same in duration when it comes up.  It's also not very loud but it's definately noticable.  How many milliseconds is the attack when set full CW?  And yes the volume definately gets louder when the FET is removed.   :sad:   I get the feeling I'm not out of the woods yet.:roll:
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 20, 2004, 10:37:05 PM
Quote
...couldnt you just program the lorlin for 5 positions, wire a jumper from 1-5, 4-5, 7-11, 10-11 and get your "all in" position as the fifth position on the switch?  This would save you adding a dpdt if it works...


Looks like the common connections are not shared by the slam/nuke implementation:

http://www.gyraf.dk/gy_pd/1176/slam.htm

So you need another switch to do it Jakob's way.
Title: All things G1176 - the new "repost" thread.
Post by: rafafredd on July 21, 2004, 12:14:05 AM
I´m searching for semiconductors and I´ve found several types of bc107. there is A, B and C versions, probably different gain. what type is the best for 1176?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 21, 2004, 07:16:47 AM
Raffafred,
Quote
I´m searching for semiconductors and I´ve found several types of bc107. there is A, B and C versions, probably different gain. what type is the best for 1176?
Most folks seem to be going with the C type.

Orson,
Quote
And yes the volume definately gets louder when the FET is removed.
After doing the Qbias calibration, that is to be expected. If you think it is a problem, put in the effort to measure and calculate HOW MUCH louder it gets with the FET out so we can discuss something concrete.
Quote
How many milliseconds is the attack when set full CW?
I don't know. Did you check the UREI manual?
Quote
The last problem is the intermitent crackling. It comes and goes but always doesn't start happening until the unit has been powered on for thirty minutes. The crakiling is not constant or the same in duration when it comes up. It's also not very loud but it's definately noticable.
Does this happen with or without input signal? The unit will distort on low frequencies if the release pot is full CW and even more if the attack pot is full CW also. Somehow this does not sound like your problem, though. Take a pencil eraser or other non conductive probe and gently wiggle FET's, transistors and other components while the unit is misbehaving to see if you can find one that makes it crackle more when you wiggle it.  My first instinct would be to pull Q1 when it starts crackling and see if it goes away. Also, a partly fried resistor might be doing it. Smell the board for burnt spots and inspect all the resistors with a magnifying glass. Bad solder joint? Loose socket connection? All things to consider. When it starts crackling, turn down the input control to see if that stops it. If it does, then it is probably something before the input pot. If not, then turn down the output control and apply the same logic. If the output control won't affect the crackling, then the problem is most likely somewhere in the signal line amp after the output pot. Use similar thinking when switching between GR and Bypass. Narrow the possibilities down as much as possible in the beginning.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: soundguy on July 21, 2004, 12:49:33 PM
Quote from: "mnats"
Quote
...couldnt you just program the lorlin for 5 positions, wire a jumper from 1-5, 4-5, 7-11, 10-11 and get your "all in" position as the fifth position on the switch?  This would save you adding a dpdt if it works...


Looks like the common connections are not shared by the slam/nuke implementation:

http://www.gyraf.dk/gy_pd/1176/slam.htm

So you need another switch to do it Jakob's way.



Isnt that lorlin a 2 pole switch?

dave
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 21, 2004, 06:20:41 PM
Allright,  got a minor problem to hunt down on one of my 1176's.  Of course I didn't find the problem until their both in the rack next to each other.  One of them isn't working right.  Passing audio, but at a far lower level than the other.

Edit:

Ok, my problem is the junction where the collectors of Q6 and Q7 feed the 1n4003 diode, and the base of Q8.  It should be roughly 15V, and I've got 23V.

the base of Q9 is getting 22V.  I'm huntin down that path to ground at present

All other voltages check out.

Thoughts?
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 21, 2004, 07:31:18 PM
Quote
Isnt that lorlin a 2 pole switch?

When I was around 10 years old I remember trying to make a tic-tac-toe game using DPDT switches...sort of feel that way looking at this rotary idea.

Yeah, the rotaries are 2 pole. But if you look at the diagram pushing in all the switches equates to what Jakob did - it creates a short between R23 and R26 on one side and R87 and R45 on the other. So like Juergen Haible pointed out on his page it's like pushing in 4 and 20; the other two won't change anything.

So to simplify things a bit...if you think about having the rotary at 4 and 20 at the same time how do you do that? Not possible because in spite of being two pole, the poles are connected at the wrong point to be able to create the required short between the points indicated above.

Bummer.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 21, 2004, 10:51:25 PM
Fum,
Quote
Ok, my problem is the junction where the collectors of Q6 and Q7 feed the 1n4003 diode, and the base of Q8. It should be roughly 15V, and I've got 23V.
Of course check your component values and placement/orientation. Make sure C14 is not shorted and is polarized correctly. Make sure C12 and C29 are not shorted. Then, since they are cheap and readily available, I would replace both 1N4003 diodes. If that still does not fix it, I would replace Q6 and Q7 as a pair, followed by Q8 and Q9 as a pair.

Ugly things may happen if you remove these transistors individually and power up.

Sorry to recommend such a shotgun approach, but that is probably what I would do.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 21, 2004, 11:13:23 PM
thanks for the suggestions, Dean

already tried replacing the diodes, same dealio.  Will check the other things.

Replacing parts isn't as drastic as it seems.  I always buy extras, expecting I'll either build more later, or will need to replace some potentially.

Regards

ju
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 22, 2004, 12:21:30 AM
Well, no further.  swapped all the components out for new ( transistors, caps, diodes).

Checked resistor values, they all are on.

Went back through checking for shorts ( twice).

It's gotta be there somewhere.

ju
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 22, 2004, 07:36:45 AM
Quote
Went back through checking for shorts ( twice).
How about opens; ie., broken traces, cold solder joints? Sometimes your ohmeter is better than your eyes for checking these things.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 22, 2004, 07:55:11 AM
Also, I would squirt some signal through (~200Hz) and check AC levels at various points with my DMM, comparing figures with the other unit. Then at least you'll know more precisely where the gain is dropping off.
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 22, 2004, 01:22:12 PM
Well I found the loss in gain.  It's actually the output transformer.  Looks like one of the output pins is cold ( I was pretty careful about soldering to it, but perhaps it got too hot and the wire lifted on the inside).

I checked between my two boxes, and both of them have 23V at the base of Q8, and 22V at the base of Q9.

Can someone else check to see if this is what they have?  The schematic says it should be on the order of 15V and 14V ( from memory), is the schematic perhaps incorrect?

Have ordered new output transformer, will wait till it arrives to resume work.

Regards

ju
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 22, 2004, 05:59:56 PM
Fum,

Was the transformer failure a warrantable failure?

 :?:
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 22, 2004, 07:54:35 PM
Quote
I checked between my two boxes, and both of them have 23V at the base of Q8, and 22V at the base of Q9.

Can someone else check to see if this is what they have? The schematic says it should be on the order of 15V and 14V ( from memory), is the schematic perhaps incorrect?


The voltages at Q8 and Q9 on my unit match the schematic within one tenth of a volt, as do all the other voltages.

 
Quote
Well I found the loss in gain. It's actually the output transformer. Looks like one of the output pins is cold ( I was pretty careful about soldering to it, but perhaps it got too hot and the wire lifted on the inside).


Did you remove the transformer and verify the fault using the Lundahl datasheet and your ohmeter?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 22, 2004, 09:56:00 PM
Not yet, excellent suggestion.  Next step =).  I've gone cross-eyed starin at these boards tryin to figure where my volts are comin from.

I've swapped out all the components in the aformentioned list, and when I say checkin for shorts/opens, I'm doin it with my Fluke.

Regards

ju
Title: All things G1176 - the new "repost" thread.
Post by: dale116dot7 on July 24, 2004, 02:55:53 AM
To me the transformer doesn't make sense - at least to cause your voltage shift - it's on the other side of a coupling capacitor.

What normally sets that voltage is going to be the following:

R29 and R30 form a voltage divider setting the bias voltage of Q5.

R32 and R34 form a voltage divider in a feedback network. The rest of the output amp tries to servo the voltage so an input voltage of 5V results in a voltage of about 4.3 at the emitter of Q5 (0.7 volt difference between base and emitter as a rule of thumb). Taking 4.3 volts * R34 / (R34 + R32) means the output should sit at about 13.5 volts.

It's possible there's something else wrong with the output amp, too, possibly a short or open that causes it to almost work. If the output level is quite low then it's possible the amp is broken and you're just getting output  from Q5 through R34 and through the output. I would not try troubleshooting the audio portion until you have the DC voltages where they are supposed to be.

There's one other thing that could cause the 23 volt output and also a strange sound - oscillation in the output amp. C12, R36, and C27 set the bandwidth of the amplifier and if something is wrong with any of those it might oscillate in the RF region, and this may cause the output to look more-or-less normal (or maybe not) but the DC offset is strange. Normally if you put your finger on various points on the PC board you'll either make it worse or better - watch that DC voltage.

If you post the various voltages - in particular, every pin (collector, emitter, base) of all of the transistors, then someone here should be able to point you to the problem fairly quickly. A difficult thing with feedback amplifiers is when they quit they tend to go to one power rail or the other, so you can't just troubleshoot it stage-by-stage.

One other thing that might be obvious - did you put in PNP transistors for Q6 and Q7 (BC560's)? Are they backwards - or do you have reversed-package parts?

Hope this helps. I just finished troubleshooting my G1176 and it's working now. I put in a 560k resistor in place of a 560 ohm resistor and it didn't work.
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 25, 2004, 01:01:00 AM
Quote from: "dale116dot7"
To me the transformer doesn't make sense - at least to cause your voltage shift - it's on the other side of a coupling capacitor.



Your completely correct here.  What I was saying is that I have two problems.  On the one unit, the reason it's output is not the same as the other is because of the transformer problem.  

both of them have this voltage shift problem, which is a problem I haven't gotten to the bottom of yet( and haven't had much time for lately, I've been in "keep the drummer happy with his drum tone") mode for several days now.  

Just got the replacement traffos, givin it a go again ( if it wasn't bloody 100 degrees here today.  Ya, I know, we're heat wimps here in the PNW, but I'm used to it being grey and 50 )

The unit with the good traffo but still the voltage problem outputs at a decent level, just isn't quite right soundwise.  Will get to the bottom of this =)

I'll do the diligence and post a complete pin/voltage viewpoint.

Thanks for the help

ju
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 25, 2004, 02:24:46 AM
Ok, heres the news:

Q5

E 4.48V
B 4.93V
C 28.24V

Q6
E 28.82V
B 28.25V
C 23.86V

Q7
E 29.48V
B 28.82V
C 23.86V

Q8
E 23.29V
B 23.87V
C 30.41V

Q9
E 14.20V
B 22.55V
C 0V

I just made the measurements, I'm gonna go back through what ya said dale, and see if I can make sense of it =)

Regards

ju
Title: All things G1176 - the new "repost" thread.
Post by: dale116dot7 on July 25, 2004, 10:57:32 AM
Q5

E 4.48V
B 4.93V
C 28.24V

This stage looks good.


Q6
E 28.82V
B 28.25V
C 23.86V

This stage almost looks good. The C voltage is off because of something later.

Q7
E 29.48V
B 28.82V
C 23.86V

This also looks good. Same thing as above, since Q7 and Q6 form a darlington pair.

Q8
E 23.29V
B 23.87V
C 30.41V

This basically looks right, but why the voltage shift?

Q9
E 14.20V
B 22.55V
C 0V

This appears to be the culprit. The hint here is that there is no 0.7 volt difference between B and E. Check the pinout of this transistor and verify that it's the right type (PNP) and put in the right way. If it is ok, check out R41 for an open or wrong value.

One additional note:

If that's a misprint and it's actually 24.20 volts on E, than this stage is working and I'd look for a 9.3k resistor in place of the 4.3k resistor, or maybe a 1k resistor in place of the 2k resistor (R32 and R34). Either one would result in a shift like this too.

Good luck!
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 25, 2004, 01:30:29 PM
Ok, think I've found it.  Damn eyes and brain.

The resistors R40 and R41 after Q8 and Q9 are 4.3 ohm, not 4.3K

I kept seeing 4R3 as 4K3.

Thanks Dale

I love those "Big Duh!" moments.

I've been staring at this for hours, sure enough ( didn't have 4.3 ohm in stock, but luckily, did have 8.6 in parallel), swap for the correct values, and watch those voltages stand in line the way they're supposed to.


ju
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 25, 2004, 02:30:15 PM
Good work, Dale and Fum!

 :thumb:

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 25, 2004, 10:32:27 PM
Hello..


 Wiring up my G1176 and I am not quite sure where wire # 1*is supposed to go? I am using a luhndal input transfo.
It is the hole labeled #1 and it has a *

 It appears that people wire things a bit differently by looking at others pictures that have been posted. :?


 Thank you
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 25, 2004, 10:33:20 PM
With the optional traffo input, connect to the 1* ( the * are used if you have the traffo there, like the resistors and caps up in that section).

Regards

ju
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 25, 2004, 10:37:16 PM
Thanks FUM,

 Question:

 So.. pin #1 from the input potentiometer which would normally go to
hole #1 (input gain) goes to hole labeled #1* instead if I follow you correctly. So pin # 1 (input gain) will be left empty? :?


 :wink:
Title: All things G1176 - the new "repost" thread.
Post by: dale116dot7 on July 26, 2004, 12:00:21 AM
Yes, the 'PIN 1' spot is left unconnected. The NE5532 input stage will not be used - its output goes nowhere if you put in those parts - you can eliminate the NE5532 and all of its support components.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on July 26, 2004, 04:23:46 AM
Thanks Guys!

 That was one of  the last things I needed to get figured out as I
am finishing this thing up. I went ahead and have done the 1:2
Mod on the output transfo for the extra 12db of gain. which was
fairly simple.. 4 cuts with my carbide cutting wheel/ dremel
and solder 4 jumper wires. easy enough.

Another couple questions I have are:

 1) is there anything else I need to do with the transfo
as far as the mod is concearned.

2) I am wondering if I should connect that extra ground wire
to the bottom of the PCB for less hum or just in case there may be
some hum cause I would rather do it now than take the board out
10 times to add finishing touches as I am hoping this thing will
work the first time up and just need calibrating(fingers crossed)

QUTOE FROM FUM:

I also took some 14 guage solid copper and soldered it around the perimeter of the ground plane on the bottom of the board, as suggested in a few threads. the output traffo is also wired as per the Chef suggestion, for increased gain.

No hum at all from these units.

ju

QUOTE FROM FALLOUT:

I've got Labs' Gyraf 1176 PCBs... Has anyone built these yet? I'm curious if the ground around the circuit needs to be fixed as I remember people having noise/hum problems with the current layout due to the ground not being thick enough? If so, did you just scrape the solder mask off of the GND and solder a thicker piece of wire around it?

-Jay

QUOTE FROM GYRAF:

In stead of scraping off the solder mask - which would look ugly - simply run a good piece of wire around the board, and solder it to the points where components meets ground, that is, at the ground pads..

Jakob E.

 
This answers my question about the  extra Ground for reduced hum.
(talking to myself again ...kinda like OWEL does=)  

Thank-you
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on July 26, 2004, 04:45:47 AM
I figured I'd try reposting my problem in this thread...

Input gain - I have some heavy limiting (-6 to -10 db) occuring starting at around 1-2 on the dial with a balanced or unbalanced input at all ratios. Think this is strictly Q bias adjustment (I did the procedures like 3 times) or more? It's unusable this way because I get barely any output gain.

Also - The ratios seem to be backwards. I checked the wiring, but both channels I built react the same way. What could cause this? My markings are fully CCW to CW: 1:4, 1:8, 1:12, 1:20. Meter showing more GR reduction with 1:4 than with 1:20.

Measuring voltage at point 22 to GND:
with 1:20 ratio = -6.3V, approx 90k to GND
with 1:4 ratio = -2.08V, approx 47k to GND

If I decide to do the output transformer flip for more gain, that is going to make the VU meter mode not accurate to 0dbu = +4dB right?


Pic of my 2nd board waiting for assembly (minus a BD245 that I forgot):
http://www.jnd.com/kdawg/kd_1176_board.jpg

thanks
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 26, 2004, 07:55:17 AM
Hi kdawg,

Are you using the right BF245 A-version FET's? If so, try interchanging the audio and meter fets.

Check that you have around 1x gain from input to input level pot top. A wrong resistor in the input amplifier could mess up things here.

Ratio switching is probably fine - it also change threshold setting when changing ratio. So the higher gain reduction at low ratios is not an effect of higher ratio, but of a lower threshold.

Flipping the output transformer won't affect meter precision, as the meter is simply hooked across the output.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on July 26, 2004, 08:29:24 AM
kdawg - I've read that you should probably put a small heat sink on your voltage regulator. I haven't powered up a G-1176, so I'm not sure how hot the regulator gets without a heat sink, but I just thought I'd mention it since I'd read it on Gyraf's site.
Title: All things G1176 - the new "repost" thread.
Post by: dale116dot7 on July 26, 2004, 10:57:57 AM
I had the same problem (low gain) and I looked at the FETs I soldered in, they were BF245C. Obviously wrong - I didn't check the suffix. I didn't have any BF245A FET's but I used 2SK170's which have a 1.5V threshold voltage, and they worked - it calibrated up just fine.

My voltage regulator gets warm without a heatsink, but not overly hot. I will install one.
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 26, 2004, 01:14:03 PM
Okay, I'm not out of the woods yet, but first, to Nick:

If you've got the board out still, I'd add the extra ground plane reinforcement.  But that's just me =).

One of my units is complete and running.  The other, I fixed the voltage problems, but managed to bugger the metering ( which was fine).  In troubleshooting the voltage problem, I at one point smelled smoke(didn't see it), and the metering hasn't been correct since then.

Here's what it does:

The VU rises maybe halfway, and then sinks back to zero, over and over.  If I meter vu output, the voltage ramps from 0-6V, and then drops to zero again.

Somethings gotta be cooked, just need to figure out what.

As per usual, any pointers/advice appreciated.

Regards

ju
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 26, 2004, 01:18:14 PM
Fum,

The meter circuit is the two trimmers, the meter fet, and the TL071. Try changing the meter fet and the TL071..
Title: All things G1176 - the new "repost" thread.
Post by: fum on July 26, 2004, 01:21:56 PM
Thanks Jakob,

Did try swapping the TL071 already ( as it's socketed, and was easy), will try the fet next.

ju
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on July 26, 2004, 02:20:00 PM
Thanks for the info guys...

>>Are you using the right BF245 A-version FET's? If so, try interchanging the audio and meter fets.

I have two complete boards hooked up and they both react exactly the same. The FETs are marked BF2  45A.

>>kdawg - I've read that you should probably put a small heat sink on your voltage regulator.

I do have heatsinks, just not in that pic :)

I have a different batch of FETs I can try and I'll check that 1x gain at the input pot.

Do BC107's have to be BC107B or are BC107 ok?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 26, 2004, 08:37:29 PM
kdawg,
Quote
Input gain - I have some heavy limiting (-6 to -10 db) occuring starting at around 1-2 on the dial with a balanced or unbalanced input at all ratios. Think this is strictly Q bias adjustment (I did the procedures like 3 times) or more? It's unusable this way because I get barely any output gain.

Also - The ratios seem to be backwards. I checked the wiring, but both channels I built react the same way. What could cause this? My markings are fully CCW to CW: 1:4, 1:8, 1:12, 1:20. Meter showing more GR reduction with 1:4 than with 1:20.

Measuring voltage at point 22 to GND:
with 1:20 ratio = -6.3V, approx 90k to GND
with 1:4 ratio = -2.08V, approx 47k to GND


Here is some info that I feel is of great G1176 significance, but is probably overlooked by most:

Near the bottom of page 2 in the UREI 1176LN manual, you'll find a little chart titled "Threshhold vs. Output Level".

Using this chart will let one know very easily if the compressor is working within spec at the various ratio settings.

It is important to remember that the chart is written with the assumption that the output transformer is wired 1:2, so adjust your numbers depending on how you have the OPT set up(stock=2:1, Chef=1:1 Dean=1:2).

The 10db output gain reserve note is basically just turning down the output so one can read the results on the VU meter without pegging it.

Maybe someone knows how and is willing to cut and paste this info and post it here.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Klaus Mogensen on July 27, 2004, 10:28:25 AM
kdawg, when you adjusted the Q-bias, did you remember to turn the q-bias trimmer fully counter clockwise, before turning up the input control. This is not mentioned on the Gyraf site, but mentioned in the manual. If you forget this you will end up with the problem you describe.

Klaus Mogensen
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on July 29, 2004, 01:31:21 AM
Ok... I've built 4 channels of 1176s, and they all act the same way. I can't turn the input pot above 2-3 or the signal just gets slammed too much. Can someone tell me if this Q bias calibration seems correct?

Q Bias
Release: Fully CW  (Fast)
Attack: Fully CW (Fast)
Input: Fully CCW (off)
Output: Fully CW
Ratio: 1:4
Meter: Bypass
Q bias: fully CCW

Signal Generator: 0.245 V (AC) sine wave 250 Hz
Measuring across input pins 2 and 1 & 3 for ground

1. Turn up input control until I get 0.100 V AC, measuring across output pins 2 and 1 & 3 for ground

2. Rotate Q Bias until reduced to 0.089 V AC across output. [ 1 dB = 20 log (0.100 / 0.089) ]

GR Meter:
Release: Fully CW  (Fast)
Attack: Fully CW (Fast)
Input: 12 o'clock
Output: Fully CCW (off)
Ratio: 1:20
Meter: Bypass

Signal Generator: 0.050 V (AC) sine wave 250 Hz
Measuring across input pins 2 and 1 & 3 for ground

1. Switch to GR meter, with no input, set meter zero adj so dial reads 0 db.

2. Switch back to bypass.

3. Adjust Output knob till 0.050 V AC measuring across output pins 2 and 1 & 3 for ground (unity gain)

4. Turn on GR metering.

5. Turn up signal generator voltage till 1/2 input V = output V.

6. Set GR meter adj so meter reads -6 db

7. Remove signal. Re-set zero if necessary, plug signal back, set GR meter adj so still get -6 db. Repeat if necessary.

---

I did Chef's mod for the output, much beter! So if I can nail this input reduction, they are finally done!
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on July 29, 2004, 07:59:03 AM
Quote
I can't turn the input pot above 2-3 or the signal just gets slammed too much. Can someone tell me if this Q bias calibration seems correct?
If you are sending a very hot signal in , this will happen. It sounds like you set the Qbias correctly.

I'll just repeat what I suggested in my last post: Go to the bottom of page 2(specifications) in the UREI manual where it says 'Input vs. Threshold', and check your unit against their numbers.

 I thought the threshold was way low on mine as well(more sensitive at 4:1 vs 20:1 etc.), but it turns out that it is right on the money. This thing goes into compression very easily.

Anyway, check it out and see what you get.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 31, 2004, 02:26:29 AM
Hi all.  Well I gotta say my G'76 is really working very nicely.  Thank you Dean and Jakob! It's a very good compressor and much smoother than I anticipated.  Calibration finally seems to be correct.  BUT I am having a buzz noise kinda like a ground loop.  Actually I am pretty sure it is a ground loop.  I can have nothing plugged into the input xlr and still get the buzz/humm from the output xlr.  The funny thing is it wasn't there before.  I am listening to the first recordings I made with my G'76 and there was no humm/buzz.  Could this be due to unshielded cable?  I did solder a thick wire around the PCB ground as Jakob recommended.  I even took the compressor to a diffferent location to see if it was my electrical source but the humm/buzz was still there. No matter what I do to the pots or controls of the unit,  it still buzzez/humms at the same level.   Question number two is I have a 1/4 watt resistor on the Ratio switch(the 10Mohm),  is that ok?  

TIA,

Ors
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 31, 2004, 05:33:06 AM
1/4W resistors are OK, but for the 1K1 regulator adjustment resistor.

Your hum may come from your PSU - try measuring ripple voltage on the -10 and the +30V.

If it worked perfectly earlier, it may be something like addition of the meter light that strains the PSU and makes excess ripple? Try removing meter light and recheck..

If this is the problem, you may need to feed your meter lights directly from transformer secondary AC,  or use a light with less current draw..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Klaus Mogensen on July 31, 2004, 09:59:26 AM
I made some attack and release time measurements on my unit to check that it is working as expected. There was a fairly good agreement with the values from the manual.

I have posted some graphs and the resulting times on the following site:

http://medlem.jubii.dk/klausdiy/experiences.html

Sorry for the all the damn commercials on this page, but it was for free.

Best regards, Klaus
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 31, 2004, 10:38:38 AM
Thanks Klaus,

These are good measurements to have and refer to (I hope you'll keep them on your page for a while..)

About the actual timing, remember that this is a feedback-sidechain construction, and will thus have somewhat different timing at different ratio settings. Higher ratios > faster timing

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on July 31, 2004, 09:18:21 PM
Quote from: "gyraf"
Your hum may come from your PSU - try measuring ripple voltage on the -10 and the +30V.
Ok I'll do that once I read up on how to do this.  By the way,  I disconnected the output xlr wires to the pcb and the hum was still there.  Then I disconnected the power supply from the pcb and the humm/buzz was still there!  I kept the star ground connected though.  So to recap, I had the #1 pins from both input and output xlr's connected and joined at the star ground nut near teh power IEC.  Ofcourse,  the ground from the IEC was connected to these aswell.  

Quote from: "gyraf"
If it worked perfectly earlier, it may be something like addition of the meter light that strains the PSU and makes excess ripple? Try removing meter light and recheck.
 I tried removing the light and it was still present.  Besides I had the light working before when the humm/buzz was no present.  The buzzing sound cyclical,  if this helps.  Actually there is the cyclical buzz accompanied by a lower pitch humm.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 02, 2004, 10:57:28 PM
Calibration problems!
I am trying to follow this procedure below:




Quote from: "kdawg"
Ok... I've built 4 channels of 1176s, and they all act the same way. I can't turn the input pot above 2-3 or the signal just gets slammed too much. Can someone tell me if this Q bias calibration seems correct?

Q Bias
Release: Fully CW  (Fast)
Attack: Fully CW (Fast)
Input: Fully CCW (off)
Output: Fully CW
Ratio: 1:4
Meter: Bypass
Q bias: fully CCW

Signal Generator: 0.245 V (AC) sine wave 250 Hz
Measuring across input pins 2 and 1 & 3 for ground

1. Turn up input control until I get 0.100 V AC, measuring across output pins 2 and 1 & 3 for ground

2. Rotate Q Bias until reduced to 0.089 V AC across output. [ 1 dB = 20 log (0.100 / 0.089) ]

GR Meter:
Release: Fully CW  (Fast)
Attack: Fully CW (Fast)
Input: 12 o'clock
Output: Fully CCW (off)
Ratio: 1:20
Meter: Bypass

Signal Generator: 0.050 V (AC) sine wave 250 Hz
Measuring across input pins 2 and 1 & 3 for ground

1. Switch to GR meter, with no input, set meter zero adj so dial reads 0 db.

2. Switch back to bypass.

3. Adjust Output knob till 0.050 V AC measuring across output pins 2 and 1 & 3 for ground (unity gain)

4. Turn on GR metering.

5. Turn up signal generator voltage till 1/2 input V = output V.

6. Set GR meter adj so meter reads -6 db

7. Remove signal. Re-set zero if necessary, plug signal back, set GR meter adj so still get -6 db. Repeat if necessary.

---

I did Chef's mod for the output, much beter! So if I can nail this input reduction, they are finally done!


I have gotten to step 1 , but I get no increase or decrease
when I adjust the input control. I have the 250hz/.245 V AC
on input pin 2 and 1  (do i need to jumper pin 1&3?)
As far as  I know I got my pots and XLR's wired correct.

 :?


Here are some of my measurments:

Q2
E .536
B 1.034
C 2.195

Q3
E 1.595
B 2.194
C 12.57

Q4
E 11.98
B 12.57
C 30.44

Q5
E 4.37
B 4.81
C 28.73

Q6
E 29.23
B 28.66
C 14.30

Q7
E 29.88
B 29.25
C 14.32

Q8
E 13.72
B 14.33
C 30.42

Q9
E 13.66
B 13.0
C 0


Q12
E 3.911
B 4.45
C 15.13

Q13
E 14.5
B 15.3
C 30.42

Q14
E 2.9
B 3.4
C 16.9

Q15
E 16.3
B 16.9
C 30.37


The Measurments seem ok  :?:
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 03, 2004, 09:21:26 AM
Quote from: "Zee1usa"
 (do i need to jumper pin 1&3?)
 I believe so, Zee.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 03, 2004, 03:47:41 PM
Zee1usa,
Quote
I have gotten to step 1 , but I get no increase or decrease
when I adjust the input control. I have the 250hz/.245 V AC
on input pin 2 and 1 (do i need to jumper pin 1&3?)
As far as I know I got my pots and XLR's wired correct.

Pin 1 is wired to ground permanently(0V).
Pin 2 carries the positive swing of the input signal (+).
Pin 3 carries the negative swing of the input signal (-).

If your signal generator's output is balanced, it should be connected as described above.

If your signal generator's output is unbalanced, connect pin 3 to pin 1(ground), and apply signal to pin 2, using pins 1 or 3 as ground.

Basically, if you want to connect unbalanced gear, you need to connect the low side of the balanced connection (-), (pin 3) to ground (0V), (pin 1). That makes your balanced input or output unbalanced.

You should have roughly unity gain up to the high side of the input pot.

If your question was about something else, or I misunderstood you, please say so.

Orson, did you get the buzz to go away? It sounds like it wasn't even coming from the PCB...

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 03, 2004, 07:09:06 PM
Hey Dean :thumb:

Thanks for asking.  Well three things were happening.  Two were buzzes with oscilation and one is a hum.  The external sound card (emagic emi 2/6 USBsound card) was creating a problem. So I have three sound cards to choose from.  I switched to another one and the one buzz was gone.  then I wiggled the power chord connected to the IEC and the other higher pitched buzz went away but comes back now and then and then I wiggle it again and it goes away.  But the Hum, well its still there.  it's low frequency and low volume,  but you know me,  i want perfection.  It gets the loudest when the ouput pot is turned all teh way down ( full CCW) The hum gets the softest when the output pot is turned to around 12 o'clock.  I have shielded cable in the unit,  I have the torodial transformer far away from the audio trannys,  I have short jumper wire under the pcb ( for the Chef mod.) I have a thick wire soldered around the ground trace connected to star ground.  At this point,  I don't know what to do.  Jakob in a PM told me to try different grounding schemes. I'm game but as usual have no education to refer to with these things.  Other than that I took it to a gig and it worked great.  I did some Bee-Gee covers and it really helped get that falseto vobrato thing going real nice.  I love playing with vocal volume wiht this compressor!  Despite the Hum,  this thing rocks!
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 03, 2004, 09:13:22 PM
Quote
Hum, well its still there. it's low frequency and low volume, but you know me, i want perfection. It gets the loudest when the ouput pot is turned all teh way down ( full CCW) The hum gets the softest when the output pot is turned to around 12 o'clock
Yeah, that is the one related to the grounding scheme. Just for kicks, put the thick wire you added around the PCB and the IEC ground wire to the single grounding point at the chassis; nothing else. All the other grounds should just go to their respective points on the PCB.

Are you floating the sheild at one end on your pot runs?
Quote
I have short jumper wire under the pcb ( for the Chef mod.)
Based on your gain readings, you don't have this mod(Chef mod=1:1); you have the 1:2 mod(better in my opinion because it's closer to the original specs). That is unless you changed something since we made all those gain measurements.

Good luck,

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 03, 2004, 09:26:26 PM
Quote from: "deanp920"
Yeah, that is the one related to the grounding scheme. Just for kicks, put the thick wire you added around the PCB and the IEC ground wire to the single grounding point at the chassis; nothing else. All the other grounds should just go to their respective points on the PCB.
 Will do.  i'll let you know the results.  

Quote from: "deanp920"
Are you floating the sheild at one end on your pot runs?


Oh,  there you go speaking Japanese again :P  No, I am not a police officer busting drug rings and if I was I wouldn't make my police badge obvious by floating it around for people to see!  Ok,  now tell me what you asked me means. :?


Quote from: "deanp920"
Based on your gain readings, you don't have this mod(Chef mod=1:1); you have the 1:2 mod(better in my opinion because it's closer to the original specs). That is unless you changed something since we made all those gain measurements.
 My apologies, you are correct.  I don't have the Chef mod  :roll:
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 04, 2004, 12:20:45 AM
Quote
deanp920 wrote:
Are you floating the sheild at one end on your pot runs?


Oh, there you go speaking Japanese again :P No, I am not a police officer busting drug rings and if I was I wouldn't make my police badge obvious by floating it around for people to see! Ok, now tell me what you asked me means.  

:green: Well, it's probably not a big concern, but the best way to run from, say, the PCB to the input potentiometer would be to use a cable with 3 conductors plus a sheild; the sheild would then be connected to the same pad on the PCB as the potentiometer's ground wire, while at the other end of the cable the sheild would not be connected to anything.

But lots of folks use 2 conductor cable plus a sheild, and with this arrangement one must use the sheild as the ground conductor as well, connecting it at both ends of the cable run. Now the sheild has a little bit of current flowing through it; something that might contribute to ground loop-induced hum. I suppose you could run a separate ground conductor alongside the 2 conductor sheilded cable so you could float the pot end of the sheild as in the first scenario.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 04, 2004, 02:18:40 AM
Hello Dean (and Jakob),

 The signal gen input is now balanced.

FYI: I have done your output transfo mod (cut 4 traces and jumped 4 wires)

I tried the UREI manual procedure for calibration of Q bias.
Inject a 1K signal at 0db/.775 (i was able to get .765 out of my sig gen)
input= full ccw
output= full cw
attack= full ccw
release= full cw
ratio= 20:1
meter=VU or 4+db
Q bias= full ccw


when i adjust the input gain I get no response on the VU even if I try adjusting the Q bias pot as well ..nothing!
This is my first task, to get past this point. I was thinking that this
is the procedure I should follow because I have done the mod you suggested on the output transfo?

I have also tried the calibration for Q bias that Kdawg posted.

Here is Kdawgs procedure:

Q Bias
Release: Fully CW (Fast)
Attack: Fully CW (Fast)
Input: Fully CCW (off)
Output: Fully CW
Ratio: 1:4
Meter: Bypass
Q bias: fully CCW

Signal Generator: 0.245 V (AC) sine wave 250 Hz
Measuring across input pins 2 and 1 & 3 for ground

1. Turn up input control until I get 0.100 V AC, measuring across output pins 2 and 1 & 3 for ground

2. Rotate Q Bias until reduced to 0.089 V AC across output. [ 1 dB = 20 log (0.100 / 0.089) ]



But I am not sure if i should follow his
procedeure because I think he did the chef output mod
and I have done your mod (not chef's)?

anyways.. I tried Kdawg's procedure and I got some output
but while tweaking the input/output knobs. Not sure If this
is a good step in the right direction, but here are some pics:

settings adjusted per Kdawg calibration "Q" bias
scope is flat or 0 volts.

(http://img.photobucket.com/albums/v359/zee1usa/1176%20waves/1.jpg)

Output gain up a 1/4 turn and getting some output signal
4Vpp (probe on x10) Input gain is still at full CCW

(http://img.photobucket.com/albums/v359/zee1usa/1176%20waves/2.jpg)

Output gain up 1/2 way starting to clip about 5vpp (x10 probe)
Input gain is still at full CCW

(http://img.photobucket.com/albums/v359/zee1usa/1176%20waves/3.jpg)

Output and input at 1/2 way up. 5vpp approx. (scope on 10x)

(http://img.photobucket.com/albums/v359/zee1usa/1176%20waves/4.jpg)

Both input and output at full CCW 5Vpp

(http://img.photobucket.com/albums/v359/zee1usa/1176%20waves/5.jpg)

Input and Output 1/4 way up. 2Vpp

(http://img.photobucket.com/albums/v359/zee1usa/1176%20waves/6.jpg)

Hope these pics may help somewhat in going forward on
calibrating this thing?


Checked the BF 245A fet and the G-S-D are stuffed proper.

All voltages on transistor E-B-C  seem to be ok ..as posted above.

XLR's and potentiometers are wired properly and all else as well.

All component values are correct and stuffed properly.



Thank you for any help you can offer/advise

 :?
nick
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on August 04, 2004, 02:46:35 AM
Remember you won't get any meter display on bypass mode... only on GR or VU. The output procedure works fine with any output mod as far as I know, since the metering is connected on the output of the transformer.

Are you measuring voltage visually on the scope, or using a DMM to get the value? I used the DMM on the input, then switched it to output.

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 04, 2004, 03:15:51 AM
Thanks for the quick reply Kdawg!

Quote from: "kdawg"
Remember you won't get any meter display on bypass mode... only on GR or VU. The output procedure works fine with any output mod as far as I know, since the metering is connected on the output of the transformer.

Are you measuring voltage visually on the scope, or using a DMM to get the value? I used the DMM on the input, then switched it to output.

-kdawg


Hello Kdawg,

I have 250hz and .245 measured on my DMM (true rms)
all knobs tweaked per your procedure.

 I have tried to follow your procedure exactly and am not getting
any voltage at all on the output ..none (on the DMM)
while turning the input gain from the full ccw position slowly towards the cw position . :oops:

I do realize the The meter only works in "GR" and "VU"
and not bypass. I only was looking at the VU while trying the UREI
procedure and not yours =}

 :?  I will keep scratching my head.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 04, 2004, 11:47:18 AM
Zee1usa,

Let's back up a little and try to get on the same page here. Please bear with me.


Use a 50mV, 250Hz input signal. Measure with your DMM for now and hold off on the scope(perhaps use it to look for clipping only right now). This way we can compare AC readings in RMS.

With this input signal, put the input and output at max(full CW). Ratio = 20:1. Attack and release don't matter, just set them like the manual says. Unit in bypass. Measure across input XLR pins 2 and 1&3. You should have ~50mV.

Measure from the input potentiometer wiper to ground. You should have ~50mV(a little less if you have the transformer input...I'm losing about 15mV, or 3db through the input transformer). So, 50mV at the input wiper with the IC input, or 35mV at the input wiper with the transformer input.

At this point, I would hop over to output XLR pins 2&3 and measure across them with the DMM. Turn the Qbias pot full one way or the other until you have max signal. You should have about 4.8V with no clipping(~6.8 with the IC input). Back off the Qbias trimmer until you have about 4.3V(~6V with the IC input) and that should set the Qbias fairly close. You just want Q1 to start cutting off a little bit, that's all we're doing here.

See if you can get this far, and if not let us know where things fell apart.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: nwsoundman on August 04, 2004, 02:02:13 PM
I can come out tonight or tomorrow night if you want. This should be easy to figure out.


Kirk
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 04, 2004, 06:46:14 PM
Quote from: "deanp920"
Zee1usa,

Let's back up a little and try to get on the same page here. Please bear with me.


Use a 50mV, 250Hz input signal. Measure with your DMM for now and hold off on the scope(perhaps use it to look for clipping only right now). This way we can compare AC readings in RMS.

With this input signal, put the input and output at max(full CW). Ratio = 20:1. Attack and release don't matter, just set them like the manual says. Unit in bypass. Measure across input XLR pins 2 and 1&3. You should have ~50mV.

Measure from the input potentiometer wiper to ground. You should have ~50mV(a little less if you have the transformer input...I'm losing about 15mV, or 3db through the input transformer). So, 50mV at the input wiper with the IC input, or 35mV at the input wiper with the transformer input.

At this point, I would hop over to output XLR pins 2&3 and measure across them with the DMM. Turn the Qbias pot full one way or the other until you have max signal. You should have about 4.8V with no clipping(~6.8 with the IC input). Back off the Qbias trimmer until you have about 4.3V(~6V with the IC input) and that should set the Qbias fairly close. You just want Q1 to start cutting off a little bit, that's all we're doing here.

See if you can get this far, and if not let us know where things fell apart.

Dean



Hello Dean,

  Thanks for the help!

ok, I am using a 250hz 70mv signal because that is the lowest this
signal generator will do. so I inject this signal into the input
measure the ground and wiper on the input pot and I get
51mv and this is what I am expecting there considering I am using the input transfo, so were off to a good start (baby steps  :grin: )

Next, I measure the output XLR between pin2 and 1/3
with input and output potentiometers full CW.

But if I adjust input and output potentiometers full CCW
I am getting 6.95VAC true rms. "Q" Bias pot
does not seem to do anything.

Thanks for the advise it is very much appreciated!

Nick



NWSM:

 tonight sounds good!
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 04, 2004, 08:42:56 PM
Docta Dean,

    Well I did as you recomended and the hum got a little worse  :green:.   No problem though this just proves that it's definately a ground hum.

I have my star ground as one of the bolts that holds the IEC to the chasis.  I am wondering if this is a bad thing because the Toroidal transformer is between 2 and 3 inches away from it.  Perhaps I should create a new star ground closer to the xlr's which is farther away from the toroidal tranny?
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 04, 2004, 10:28:53 PM
Hello dean,

 Here is an update. It appears that I am getting proper voltage signal
on the output XLR, but the "Q" Bias potentiometer has no effect at all.

 I measured the Q1 fet/transistor. I am getting:

Q1
G = -1.92v
S = 0v
D = 0v


I think there is an issue here. There is alot of stuff tied to this.
I will keep looking. Any questions you may ask to clue me in
would be more than welcome.

Thank you Dean!

 :?
Nick
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 04, 2004, 11:17:30 PM
Nick,

Ok, I get about -1.8V at the gate of Q1 with my bias set for 1db cutoff. I can adjust this from -2.3V to 0V with the Qbias trimmer.

The less negative this voltage becomes, the more Q1 goes low and attenuates the audio. Actually, there is a fairly abrupt point where Q1 begins to clamp down. We set the bias just slightly inside this spot.

May I assume that this voltage does not change when you turn the Qbias trimpot?

If so, go back to the schematic and PCB overlay and trace through the Qbias supply circuit, starting at the -10V PSU then proceding through the Qbias trimpot to find out why you can't adjust the bias voltage on Q1.

Perhaps I'm making a hasty assumption. Let me know how it's going.

Orson,
Quote
I have my star ground as one of the bolts that holds the IEC to the chasis. I am wondering if this is a bad thing because the Toroidal transformer is between 2 and 3 inches away from it. Perhaps I should create a new star ground closer to the xlr's which is farther away from the toroidal tranny?
Well, it is hard to say; I have my star point set at the mounting screw for the input XLR. This is the spot called for by Jakob. Make damn sure you clean this spot to bright metal to ensure a SOLID electrical connection. When it comes to grounding, think BEEFY. Think BLACK HOLE for electrons. Make sure the panels comprising the chassis are making solid electrical connection with each other. Play with it to see if you can make an improvement and if you can't go back to what you had originally. Sometimes I'll use a length of heavy, tinned buss wire that I'll solder between various 0V, or ground, locations to try and get some clues about what helps. Don't waste time with clip leads; those will drive you crazy.

Try using the input XLR screw as star ground first. Put the heavy buss wire off the PCB here and the IEC ground here.

Hope that helps.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 04, 2004, 11:49:29 PM
Hi Dean,

Quote from: "deanp920"
Nick,

Ok, I get about -1.8V at the gate of Q1 with my bias set for 1db cutoff. I can adjust this from -2.3V to 0V with the Qbias trimmer.

The less negative this voltage becomes, the more Q1 goes low and attenuates the audio. Actually, there is a fairly abrupt point where Q1 begins to clamp down. We set the bias just slightly inside this spot.

May I assume that this voltage does not change when you turn the Qbias trimpot?

If so, go back to the schematic and PCB overlay and trace through the Qbias supply circuit, starting at the -10V PSU then proceding through the Qbias trimpot to find out why you can't adjust the bias voltage on Q1.

Perhaps I'm making a hasty assumption. Let me know how it's going.



Dean




My Q Bias trimmer is adjusting this voltage.

But I am not getting any change at the base of Q2.

I was speaking with NWSM, and we are thinking something may be wrong with Q1?

On initial power up FYI I had wire (17) and wire (15) swapped
then I noticed this shortly after and  corrected this.

Do you think this could of done damage to Q1 or related transistors?

I'll keep looking, but it may be narrowed down...

Thank you Dean!

 :thumb:

zee
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 05, 2004, 01:00:18 AM
Hey Dean,

 Good news!  :grin:

 I was chatting on the phone with NWSM/KIRK and we talking about Q1
possibly being bad and then he had me probe a few voltages around
Q1 and further downstream. Everything else seemed to be working correctly except Q1 was suspect. NWSM suggested I replace suspected Q1. I did and now I can make this calibration adjustment and move on the the next step. I'm not going to break out the  :guinness:  yet. :wink:

Thanks dean, your pointing me in the right direction led me to fix this.
and here's one for NWSM  :guinness:


One thing I want to ask about the input and output potentiometers.

Mine seem to be backwards, but I did wire pin 1 on the 10k input pot
to pin 1 on the pcb..pin 2..pin 3  respectively.

I thought I remember Jakob mentioning to watch out for this?? :?

Maybe you or jakob could shed some light  on this issue?


I hope this is helpful to others.
Thanks

Nick :guinness:  :green:
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 05, 2004, 01:03:51 AM
Zee,
Quote
But I am not getting any change at the base of Q2.

Are you talking about measuring change in AC signal level here?  
Quote
On initial power up FYI I had wire (17) and wire (15) swapped
then I noticed this shortly after and corrected this.

Do you think this could of done damage to Q1 or related transistors?
I doubt that mistake damaged anything whatsoever.

  If, at the turn of the Qbias trimpot, the negative voltage changes from 0V to ~-2V at the gate of Q1, then I would probably try replacing Q1, based on what you've said so far. It's nice to have a socket of some sort for Q1.

Are you using BF245A?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 05, 2004, 01:07:27 AM
Hello Dean,

 Check the previous post, I think we were both typing and you may of posted seconds after I did and not noticed (its a refresh thing)

 :wink:

Yes, I am using the "BF245A"
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 05, 2004, 01:21:36 AM
Woops! I hit submit before I caught your last post.

Glad swapping Q1 helped you break loose a bit. :grin:
Quote
One thing I want to ask about the input and output potentiometers.

Mine seem to be backwards, but I did wire pin 1 on the 10k input pot
to pin 1 on the pcb..pin 2..pin 3 respectively.
It might be your particular potentiometer. At any rate, just make sure you've got the wiper going to the right spot and reverse the other two until it works in the right direction. I like to check my pots ahead of time with an ohmmeter to see exactly what changes CW/CCW rotation causes between the wiper and the other contacts; that, along with the schematic and PCB overlay leaves no doubt about how to connect it.

FWIW, the rotation on my Qbias trimpot is opposite that stated in the UREI manual.

Dean

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 05, 2004, 05:23:46 PM
Quote from: "deanp920"
   I have my star point set at the mounting screw for the input XLR. This is the spot called for by Jakob. Make damn sure you clean this spot to bright metal to ensure a SOLID electrical connection. When it comes to grounding, think BEEFY. Think BLACK HOLE for electrons. Make sure the panels comprising the chassis are making solid electrical connection with each other. Play with it to see if you can make an improvement and if you can't go back to what you had originally. Sometimes I'll use a length of heavy, tinned buss wire that I'll solder between various 0V, or ground, locations to try and get some clues about what helps. ....Try using the input XLR screw as star ground first. Put the heavy buss wire off the PCB here and the IEC ground here.


Thank you Dean.  You know I was wondering yesterday about that "bright Metal " point you made.  It seems to me the enclosure I bought,  which is the very one Jakob lists, should be abrased to ensure good contact - "Black Hole" for the star ground point.  I will do this and I will try the input XLR screw as star ground.  Thanks again.  Oh,  by the way,  I assume you don't have this hum.  Do you?

Jakob,

Since I have the same enclosure you used, I thought I would ask you this.  When they manufactured this case do you know wether they painted over it after assembly or before? If before,  perhaps I should abrase spots on each panel corner and solder buss wire connecting each panel for better results?
Title: is it fast?
Post by: keithcamilleri on August 05, 2004, 07:35:29 PM
hi guys...

I would like to now whether the g1176 responds to compression faster then the original urei?

I.ve worked with the original one and ts a great comp but it is a bit slow has anyone compared the original with the g1176?

(promise last question0 how does it sound?

sorry 4 all th questions just want some info before I begin this project.

cheers..
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 05, 2004, 07:43:44 PM
Orson,
Quote
Oh, by the way, I assume you don't have this hum. Do you?
Yes I do. It is so low in level now that I can't hear it unless I crank my monitors or a headphone amp to max. Same or less than the 'hiss' produced by the G1176 circuit amplifiers.  Much less than a typical tube guitar amp. But that tiny bit of hum was really loud before I got the grounding sorted out with the buss wire et all. It behaves in the same non linear fasion you describe by turning the output knob. Others have mentioned this also.
Quote
I will do this and I will try the input XLR screw as star ground.
I hope that helps, but be prepared for it to get worse as well. Every chassis is different, and chasing ground loops is a form of black magic if there ever was one, at least for me. You can change the seemingly most subtle aspect of the grounding plan and have the hum just vanish, or get much worse.

Have fun :grin:

Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 05, 2004, 09:09:22 PM
Quote from: "deanp920"
Orson,
Quote
Oh, by the way, I assume you don't have this hum. Do you?
Yes I do. It is so low in level now that I can't hear it unless I crank my monitors or a headphone amp to max. Same or less than the 'hiss' produced by the G1176 circuit amplifiers.
Hmmmm....  this makes me wonder if, perhaps, I should have left things alone.  Your description of your units function ,  wait a minute ,  let me restate that,  that sounded weird.  The behavior of the sound of your G1176 sounds like what mine was doing.  Perhaps I was being too critical?  Well,  actually I can hear it without my headphone amp totally cranked but its very low.  I'll keep trying to get it better.  If not Ill go back to the scheme I had before.  And once more the cover comes off....
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 06, 2004, 02:17:40 AM
Hello Dean and all,

 I finished tuning up my G1176.

FYI

 While doing my "GR meter Track" calibration the potentiometer
was not adjusting at all down to -6dbu per the Gyraf website
calibration procedure, so I looked at the schematic and noticed the
BF245A in the circuit and thought I should change it.  Changing it fixed the problem.  :cool:

 I know about ESD and I was very precautious when stuffing my pcb.
Also, I know the 2 second rule (in and out) with the soldering iron just enough for the solder to completely flow to not overheat the components that are sensitive. I am not sure if they were damaged as DOA
or if I damaged them (most likely) but I sure find this strange
as I tried to be as careful as possible? :roll:

Any one have any input on this Fet being a sensitive little guy?

I know i have seen circuits in the past where a certain Fet/transistor
was the most sensitive to ESD  in the circuit and it was the only component that would be bad, even thought the production
staff was regularly updated on ESD procedures.

Did'nt jakob suggest to socket these things possible due
to their sensitivity (BF245A) ?

Oh well it seems to work now...

Now off to go see if it has any hum I need to tend to...
Oh ya and to squash some signals too! :thumb:


 :guinness:  :green:
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 06, 2004, 08:49:52 AM
Zee,
Quote
While doing my "GR meter Track" calibration the potentiometer
was not adjusting at all down to -6dbu per the Gyraf website
calibration procedure, so I looked at the schematic and noticed the
BF245A in the circuit and thought I should change it. Changing it fixed the problem.  
Back on the old thread at RO, I believe Jakob mentioned that the BF245A was prone to damage by ESD.

However, the problem you mention here might have been caused by a mismatch in cutoff voltage between Q1 and Q10. The BF245A's vary considerably, and it is definitely easier to adjust when they are matched. Too great a variance makes it impossible. Of course, Q10 may have just been fried like you said.

I like a socket for both Q1 and Q10.
Quote
Now off to go see if it has any hum I need to tend to...


 Let us know how your hum and noise is. Are you using a board from Gustav?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: nwsoundman on August 06, 2004, 12:31:01 PM
I hope my parts aren't zapped!!   :grin:  :shock:  :grin:
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 06, 2004, 01:19:15 PM
Quote from: "nwsoundman"
I hope my parts aren't zapped!!   :grin:  :shock:  :grin:


Not to worry nwsoundman, I used both your BF245A   :oops:

I better order a couple more  :grin:


 The good news is, I think my G1176 is working ?!?!
I does have a "hiss" to it when the gain is cranked.
Seems to be no hum, other than maybe a very tiny
minute amount of 60 cycle which may be normal?

Dean said: Are you using a board from Gustav?

YES... I am.






  Z
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 06, 2004, 01:59:20 PM
hi

has anyone made any progress with linking 2 G1176s? i know Kdawg is working on this and some others have briefly described proceedures. has anyone implemented anything with promising results?
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 06, 2004, 08:53:55 PM
I have relocated the star ground to the input XLR screw.  This has not helped but increased the hum just a tad.  So far the best place I have found is the IEC screw.  Oh well,  if I adjust the output of the G1176 and the input on my mixer I can get it to where it is tolerable.  I like to go in as hot as possible but in this situation it's better not to.  I wonder if the tranny modification added more hum than would be there ratio wise with out it?  I can't remember where,  but there as a gentlemen here posting the results of his PCB design that changed the ground trace that was more quite.  I noticed he has it cut so it doesn't go around the whole PCB.  Would that help us in our situation if we cut the ground trace with a dremel?
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on August 06, 2004, 09:38:35 PM
Orson

I have been experimenting with the grounding theing.

Chef cut the ground traces to isolate the PSU & audio grounds & then star earthed them.  He said it sorted the problem

I`m a bit cautious so I made one cut near the meter/meter lamp connection & the hum is better than it was before.  It took some lumps that appeared on the scope out.  I`m not sure if its totally cured it cos the desk that I`m using to check it is a bit flaky, so I`ve got to check it elsewhere to be sure.

I hope this helps!
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 07, 2004, 01:54:46 AM
al_p,
Quote
has anyone made any progress with linking 2 G1176s? i know Kdawg is working on this and some others have briefly described proceedures. has anyone implemented anything with promising results?
Yes, I have two linked and they work great. I matched all the BF245A's, then linked point 7 of each circuit directly via a toggle switch that selects between stereo/dual mono. No problem.

Orson,
Quote
I wonder if the tranny modification added more hum than would be there ratio wise with out it?
I could be dead wrong here, but I'm pretty sure that without the tranny mod you would have nearly the same hum issue, combined with a frustrating lack of makeup gain. The stock OPT will yeild better S/N, but I'm afraid it might not directly address the hum issue you're dealing with here.  I know the ground loop hum I had in the beginning was just as irritating with the stock OPT wiring. Try and see.

What size and type of wire do you have soldered around the PCB perimeter? Is it tacked in several places, or soldered all the way around with a continuous bead? Where does it start and stop?

Zee,  
Quote
Seems to be no hum, other than maybe a very tiny
minute amount of 60 cycle which may be normal?
Is this result with no added modifications to the stock PCB grounding scheme?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 07, 2004, 02:57:21 AM
Quote from: "deanp920"
Yes, I have two linked and they work great. I matched all the BF245A's, then linked point 7 of each circuit directly via a toggle switch that selects between stereo/dual mono. No problem.


cool good to know. thanks. here's an easy question. how are you guys matching the FETs? is there a test jig i could set up for this? or is it just putting them in the circuit and testing voltages?
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 07, 2004, 04:33:03 AM
Hello Dean,


Quote from: "Rob Flinn"

Chef cut the ground traces to isolate the PSU & audio grounds & then star earthed them.  He said it sorted the problem

I`m a bit cautious so I made one cut near the meter/meter lamp connection & the hum is better than it was before.  It took some lumps that appeared on the scope out.  I`m not sure if its totally cured it cos the desk that I`m using to check it is a bit flaky, so I`ve got to check it elsewhere to be sure.

I hope this helps!


What do you think about doing the above rob flinn/chef mentioned
about isolating PSU and Audio grounds and starring them?


Dean wrote:

What size and type of wire do you have soldered around the PCB perimeter? Is it tacked in several places, or soldered all the way around with a continuous bead? Where does it start and stop?

Dean, I used a 12AWG soldered around the perimeter tacked on in about
8 places but not with a continuous bead. Would  a countinuous bead be better? Jakob mentioned I believe this was not needed and he thought it would just look ugly.



Zee, Quote:

Seems to be no hum, other than maybe a very tiny
minute amount of 60 cycle which may be normal?

Dean Wrote:
 
Is this result with no added modifications to the stock PCB grounding scheme?

only mods are :

perimeter 12 awg tacked on in 8 places.

I have a ground LUG which has a ground from each of these points:

1) AC main.

2) direct from pcb ground/perimeter 12awg.

3) 4th chassis pin from XLR input wich is jumpered to 4th chassis pin on output XLR.


I have been thinking of any possible changes to this ground scheme
that would be for the better.

I have seen a note on Gyraf site that says:

"- Make sure that the centre tap of the 2x24V at the power transformer is connected to ground"

"- Connect 0V/Ground to chassis at - and only at - the input XLR(F) connector. Here you can also connect the mains power ground from the IEC power connector if you need that"

1) I am thinking that I may have my XLR grounded improperly

2) Should I not go to star ground direct from pcb perimeter ground
plane? Or is this ok.

3) what about ground on the toroid? It is already going to the pcb which goes straight to the ground plane, I think this should be sufficient?

4) potentiometer should be grounded? My input and output is conductive plastic (bourns 90 series) but attack and release are (Alpha) which are metal. Should these go to ground other than the (1,2&3) wires that go to their normal place on the pcb?


Thanks Dean!

 Thanks for the info on the stereo connection as well.

 :grin:
 Z
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on August 07, 2004, 07:14:34 AM
Zee, Quote:

Seems to be no hum, other than maybe a very tiny
minute amount of 60 cycle which may be normal?


This is not normal.   I & a friend have done a side by side comparison with a pair of revision H UREI`s & the g1176 (in standard form) has noticably more hum.  The revision H circuit is very simlar to the G1176 without input transformer.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 07, 2004, 09:34:33 AM
Well,  I haven't refered to the AWG and measured thickness of the wire I am using but it is soldered ALL THE WAY AROUND the PCB perimeter.  I haven't cracked open my G1176 yet to see where I started and finished it either.  Today I 'll get to that and then post the info here.   I am using thin wire for the rest of my grounding scheme.  I will try thicker wire and see if this helps.  I am tempted to cut traces but I'll be abstemious with the Dremel till I hear more.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 07, 2004, 10:41:18 AM
Z,
Quote
What do you think about doing the above rob flinn/chef mentioned
about isolating PSU and Audio grounds and starring them?
I can't comment because I have not tried it. I am satsfied with the arrangement I currently have:

No. 14AWG tinned copper busswire soldered around perimeterw/ continuous bead, starting/exiting between the pads for input/output XLR connections.

This wire goes to a lug I fastened on the mounting screw for the input XLR. AC mains ground here as well.

That is all I have done. Hum is less than hiss.

Z wrote:
Quote
Dean, I used a 12AWG soldered around the perimeter tacked on in about
8 places but not with a continuous bead. Would a countinuous bead be better? Jakob mentioned I believe this was not needed and he thought it would just look ugly.
That is probably as good as it gets. I got a very tiny improvement with a continuous bead, but you're using #12 wire compared to my #14.

Z wrote:
Quote
Seems to be no hum, other than maybe a very tiny
minute amount of 60 cycle which may be normal?
If the hum is below the noise floor of the circuit(which is relatively high, compared to modern gear), then I would say you're good to go.

Z wrote:
Quote
3) 4th chassis pin from XLR input wich is jumpered to 4th chassis pin on output XLR.
Not really necessary; try with/without to see if you get some improvement.
Quote
3) what about ground on the toroid? It is already going to the pcb which goes straight to the ground plane, I think this should be sufficient?
Yes, you've already got it at the PCB.
Quote
) potentiometer should be grounded? My input and output is conductive plastic (bourns 90 series) but attack and release are (Alpha) which are metal. Should these go to ground other than the (1,2&3) wires that go to their normal place on the pcb?
It is OK if the metal pots form a connection to the chassis through the standard mounting. You don't need to do any extra grounding on any of the pots.
Quote
2) Should I not go to star ground direct from pcb perimeter ground
plane? Or is this ok.
Yes, this is really the one and only wire, besides the AC mains, that should go to star ground.
Quote
I am thinking that I may have my XLR grounded improperly
Use 2 conductor sheilded wire; pins 2&3 use the two conductors to the PCB, and the sheild connects pin 1 to the PCB.

Rob Flinn wrote:
Quote
Zee, Quote:

Seems to be no hum, other than maybe a very tiny
minute amount of 60 cycle which may be normal?


This is not normal. I & a friend have done a side by side comparison with a pair of revision H UREI`s & the g1176 (in standard form) has noticably more hum. The revision H circuit is very simlar to the G1176 without input transformer.
Rob, when you refer to the G1176 in standard form, is that without a heavy wire soldered around the perimeter of the ground plane?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on August 07, 2004, 10:57:55 AM
Rob, when you refer to the G1176 in standard form, is that without a heavy wire soldered around the perimeter of the ground plane?

Dean


Yes & also without any of the Chef grounding mods. Just the straight PCB.



I`m intrigued by your method of soldering a heavy wire round the board perimeter.  This souinds quite a job if the board is professionally made with a solder mask.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 07, 2004, 11:11:59 AM
OK,  I used thicker wire ( 12 guage  copper ) and I went back to the original grounding scheme.  Definately lowered the hum.  The hiss is louder than the humming.  But then again it was before aswell.  But this is a marked improvement.  When I turned the output knob full CW the hum was more noticable before.  Now it's hardly noticable at all.  This makes me happy.  I don't know where I started and ended the PCB perimeter wire or what Gauge it is but it's definately not 12 guage.  It's a little thicker than standard hook up wire.   By the way my grounding scheme is as follows.  Mains IEC ground and PCB perimeter ground meet at the middle of the jumper wire connecting xlr input and output pins number #1 ( I believe but not sure about the number) .  Then from that point to the IEC screw connected to the chasis which I guess would be called Star Ground.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 07, 2004, 01:40:47 PM
Orson,
Quote
OK, I used thicker wire ( 12 guage copper ) and I went back to the original grounding scheme. Definately lowered the hum....I don't know where I started and ended the PCB perimeter wire or what Gauge it is but it's definately not 12 guage. It's a little thicker than standard hook up wire.
:?: So, what wire did you replace with #12?
Quote
When I turned the output knob full CW the hum was more noticable before. Now it's hardly noticable at all. This makes me happy.
Alright! :grin:

Quote
I`m intrigued by your method of soldering a heavy wire round the board perimeter. This souinds quite a job if the board is professionally made with a solder mask.
I'm certainly not the person who came up with this idea originally; for sure, bluebird did it on his as well as some others who I can't recall at the moment. I think Jakob may have been the first to suggest it, though I believe that using such a heavy guage may have started with me. My board is home built, so soldering the wire all the way around was no problem...I tacked it first, then came back and ran the bead.

I think using #14 solid copper or heavier is important for best results.

Zee1usa has a board with the solder mask, and it appears that he used #12 wire and just tacked it in several places(~8?) around the perimeter where I'm assuming the solder mask was scraped/sanded/filed off.

Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 07, 2004, 03:01:44 PM
Hello Dean ,



Dean Wrote:

Zee1usa has a board with the solder mask, and it appears that he used #12 wire and just tacked it in several places(~8?) around the perimeter where I'm assuming the solder mask was scraped/sanded/filed off.

Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

Dean


No, I did not try it without the Extra perimeter ground wire  :oops:
I should have, just to see if it would have been ok.

I was thinking ..why not add extra protection. sometimes
even you are trying to improve for the better, it may not be?
I dont think removing the perimeter wire would help any, but
you just never know.

Here is a pic of the perimeter ground on my second G1176
which I am finishing up now.

(http://img.photobucket.com/albums/v359/zee1usa/perimetergroundwire.jpg)



  Z
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 07, 2004, 04:02:40 PM
Quote from: "deanp920"
So, what wire did you replace with #12?


Well the wire I was using before was pedestrian hookup wire  :roll: .

Rob Flinn,

     Please keep us informed as to the results of your cut near the meter lamp connection when you get to monitor on a better board/situation.  I would like to try this too.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 07, 2004, 05:12:14 PM
Quote
deanp920 wrote:
So, what wire did you replace with #12?


Well the wire I was using before was pedestrian hookup wire  .
Sorry Orson, I didn't word my question very well. I was trying to determine if it was indeed the perimeter ground wire that you replaced with #12 wire.

Z,
 
Quote
No, I did not try it without the Extra perimeter ground wire  
I should have, just to see if it would have been ok.
Oh well, it's no big deal. Surely someone else will come along and let us know sooner or later. Rob Flinn, are your boards from Gustav?
Quote
was thinking ..why not add extra protection. sometimes
even you are trying to improve for the better, it may not be?
I dont think removing the perimeter wire would help any, but
you just never know.
I would tend to throw my guess in the same direction. That is a nice looking ground buss.

I'm a bit curious here; on mine, I continued the heavy ground wire all the way to the chassis lug. What did you do Z?  Orson?

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 07, 2004, 05:33:29 PM
Hey Dean,

Dean Wrote:

I'm a bit curious here; on mine, I continued the heavy ground wire all the way to the chassis lug. What did you do Z?



I took a 4 inch 18awg from corner of perimeter ground wire
to chassis lug. So to answer your question..No I did not continue
the heavy wire to the lug.

Thanks Dean,

        Z
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on August 07, 2004, 08:51:20 PM
Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

I tried it straight & for me it had a hum issue !
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 08, 2004, 03:56:31 AM
Hello Rob,

Quote from: "Rob Flinn"
Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

I tried it straight & for me it had a hum issue !



I did not try Gustav's board without the extra ground plane.
From what i gather around here, it can help the hum issues.

To add a perimeter ground wire like I did you need to:

1) Get a 12 or 14 awg solid copper wire. I used some leftover wire from an
electrical wiring installation.

2) Bend it into shape around the perimeter as I did in the picture.
You will need to be very careful not to block the screw holes that the pcb mount on.

3) Around the perimeter of the pcb you will notice about 6-8 ground points that you can solder to. you will need to strip the insulation where they will be soldered to the pcb perimeter. You will need to tin the copper wire in the bare spots that you stripped.

4) Solder the wire on which is tricky with just two hands. Sometimes
I put a long solder wire from my mouth, soldering iron in the other and needle nose pliers in the ohter (to hold the hot wire colse to the pcb
until solder cools). Easier said than done.

5) have a  :guinness:  or  :sam: (Two)

 :green:

   Z
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on August 08, 2004, 04:26:37 AM
I too am suffering from the hum. But I think I forgot to ground the centre tap, so I'll try that. But is this weird: I have major 60 Hz hum except when I set the OUTPUT knob to around 4! Then it's almost dead quiet.

Here's what I've tried so far (besides the centre tap grounding):
1. Moving toroid - no difference.
2. Isolating 1/4" TRS jacks from chassis - no difference.
3. Removing power jack ground - no difference
4. Unplugging VU meter light - slight difference in hum sound, but same level.
5. This is a dual unit, I tried disconnecting the 2nd channel altogether - no difference.

I have the input ground to chassis, then chassis to outlet. Output ground is shield grounded to PCB only.

I do have Chef's mod on it. No perimeter ground, Gustav rev 7 (?) boards. I'd really like to NOT have to do this if possible, I have 6 boards!

Other than that, unit works great... even stereo linking works w/pin 7 switch.
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on August 08, 2004, 05:19:21 PM
I too am suffering from the hum. But I think I forgot to ground the centre tap,

The centre tap should be connected to the ground on the circuit board, which in turn is grounded through the input connection to the chassis
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 08, 2004, 05:28:18 PM
Quote from: "deanp920"
Sorry Orson, I didn't word my question very well. I was trying to determine if it was indeed the perimeter ground wire that you replaced with #12 wire.
No it wasn't it was the other wires.  I am trying to find a place to host pics so I can post them here.
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 08, 2004, 07:38:25 PM
Hello Orson,

Quote from: "orson whitfield"
Quote from: "deanp920"
Sorry Orson, I didn't word my question very well. I was trying to determine if it was indeed the perimeter ground wire that you replaced with #12 wire.
No it wasn't it was the other wires.  I am trying to find a place to host pics so I can post them here.




http://www.photobucket.com
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 08, 2004, 08:21:03 PM
Okay ,  here is a closeup of the pins #3 jumpered with the brown wire (perimeter of PCB) soldered to the middle of the jumper wire.  Also,  there is a wire (also 12 guage) going from there to the bolt fastening the IEC in to the chassis (star ground).  Also there is another 12 gauge wire coming from the mains in ground to this point aswell. So there are four connections happening at this point all leading straight to star ground.  I remember someone at the old forum showing me pictures of this setup.  

http://tinypic.com/1kwup

http://tinypic.com/1kx9h
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 08, 2004, 08:38:49 PM
Orson,

 You probably already know this, but just in case.

 Becareful not to get any metal shavings, metal dust or any thing like that
on your circuit board of your G1176.  It can cause a short. I have seen this happen too many times on accident in other electronics devices
being damaged by this.

Cheers.

Z
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 08, 2004, 08:44:07 PM
Yeah I know.  Now that they are there what is a good way to get rid of them?
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 08, 2004, 09:03:14 PM
Quote from: "orson whitfield"
Yeah I know.  Now that they are there what is a good way to get rid of them?



Compressed Anti static spray air  in a can from Radio Shack or Office Depot etc. maybe some alcohol on a anti static Q tip?


Z
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 08, 2004, 09:38:12 PM
TWINS!!

check em out...

http://www.groupdiy.com/index.php?topic=218&start=30


They are  hum free and sounding nice! :thumb:


Z
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 08, 2004, 11:56:42 PM
Hi Orson,

I'm having trouble seeing your pictures..."page cannot be displayed", etc.


Z,

Quote
TWINS!!

check em out...

http://www.groupdiy.com/index.php?topic=218&start=30


They are hum free and sounding nice!  
That is good to hear!
 But I can't see the pics.

I'm just not wired to deal with computers!  :oops:  :roll:
 
EDIT: Ok, Z, now your pics are there. Yes, those are very nice looking.  :cool:  
Dean
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 09, 2004, 12:04:49 PM
Orson,

Quote
Okay , here is a closeup of the pins #3 jumpered with the brown wire (perimeter of PCB) soldered to the middle of the jumper wire. Also, there is a wire (also 12 guage) going from there to the bolt fastening the IEC in to the chassis (star ground). Also there is another 12 gauge wire coming from the mains in ground to this point aswell. So there are four connections happening at this point all leading straight to star ground. I remember someone at the old forum showing me pictures of this setup.

http://tinypic.com/1kwup

http://tinypic.com/1kx9h
Now I see your pictures.

Does this arrangement fix the hum on your G1176? If so, then great...don't change a thing.

However, it concerns me a bit to see you using #12 wire everywhere except for the perimeter ground wire on the PCB...the one place where it is most needed, based on the evidence presented in this thread and on my own G1176's. My guess is that if you had soldered #12 around the PCB and ran that out to the chassis lug along with the AC mains ground, that would be all you'd need.

BUT, like I said, if what you have works, leave it alone.

Quote
pins #3 jumpered
Are you talking about XLR pins? :shock:  Pins number 3 on the input and output XLR's carry half of the balanced signal and should NOT be jumpered and tied to ground, unless you want the input and output to be permanently UNBALANCED. Pins 1 on the input and output XLR's are the only ones you can legitimately jumper(only if that helps fix the hum); they should already be connected to their corresponding ground pads on the PCB, via the sheild on each cable connecting each the jack to the PCB.
 
Dean
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 09, 2004, 04:54:03 PM
Quote from: "deanp920"
Does this arrangement fix the hum on your G1176?
No not completely.

 
Quote from: "deanp920"
...it concerns me a bit to see you using #12 wire everywhere except for the perimeter ground wire on the PCB...the one place where it is most needed, based on the evidence presented in this thread and on my own G1176's. My guess is that if you had soldered #12 around the PCB and ran that out to the chassis lug along with the AC mains ground, that would be all you'd need.
I would have rather used #12 AWG but it is very difficult to do given it's thickness.

Quote from: "deanp920"
BUT, like I said, if what you have works, leave it alone.
 Well,  the hum , as  I have said before,  is lower a small bit but still there.

I guess I should try to tack on the #12 AWG wire and see if that helps.  I am afraid of damaging components though.  It takes a little longer to heat up this thick wire and therefore increases heat transfer.  

Quote from: "deanp920"
Pins number 3 on the input and output XLR's carry half of the balanced signal and should NOT be jumpered and tied to ground, unless you want the input and output to be permanently UNBALANCED. Pins 1 on the input and output XLR's are the only ones you can legitimately jumper(only if that helps fix the hum)
Well,  I have never tried my G1176 powered up wihtout this ground scheme.  I can't remember who but someone posted a pic of this scheme I have.  I was just following direction.  MY BAD I meant to say pins #1 are jumpered NOT #3.  Since I don't have a shield connected to the ground pad on the PCB perhaps this is ok.

 
Quote from: "deanp920"
 they should already be connected to their corresponding ground pads on the PCB, via the sheild on each cable connecting each the jack to the PCB.
 Next time I'll try this.
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on August 09, 2004, 06:14:48 PM
*good info here*

Ok - I was able to test out Gustav's Rev 7 boards with and without perimeter wire.

Results:
No perimeter wire - BAD hum, changes strangely with output level control.

Perimeter wire (did not attach to chassis, just a loop around ground solder points) - hum is almost completely gone! Only noticeable at really high output volume, which is louder than I'd ever go w/Chef's mod in place.

So I am extremely thrilled, finally have 6 channels working!
Title: All things G1176 - the new "repost" thread.
Post by: Zee1usa on August 09, 2004, 06:33:13 PM
Great to hear KDAWG!

This is good info for the others with the hum issue. :thumb:


Wish I had (6) G1176 :wink:
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 09, 2004, 06:50:23 PM
Quote from: "kdawg"
  Perimeter wire (did not attach to chassis, just a loop around ground solder points) - hum is almost completely gone! Only noticeable at really high output volume, which is louder than I'd ever go w/Chef's mod in place.
Hmmm.  THis makes me wonder if the perimeter wire was connected to ground would the hum increase?  Maybe I should try disconnecting my perimeter wire from ground too?
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on August 10, 2004, 03:32:09 AM
hmm, I left two dual 1176s together and they had a kid. They make a cute family...

(http://www.jnd.com/kdawg/kd_1176s_1_sm.jpg)

http://www.jnd.com/kdawg/kd_1176s_1.jpg

thank you everyone. I'm finally at peace, resting at more than a 1:4 ratio now :)
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 11, 2004, 05:07:51 PM
Quote from: "orson whitfield"
Quote from: "kdawg"
  Perimeter wire (did not attach to chassis, just a loop around ground solder points) - hum is almost completely gone! Only noticeable at really high output volume, which is louder than I'd ever go w/Chef's mod in place.
Hmmm.  THis makes me wonder if the perimeter wire was connected to ground would the hum increase?  Maybe I should try disconnecting my perimeter wire from ground too?


Well,  I answered my own question.  I tacked a 12 AWG wire around the perimeter and connected it to my ground scheme and the hum got worse.  :evil:   Well,  at least I know that won't help.  Now I am wondering if I should eliminate my scheme altogether and come up with a simpler plan.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 11, 2004, 05:30:21 PM
OK Hum is way better now that I completely disconnected the perimeter ground wire from my grounding scheme.  So for me, kdawg's technique worked.  There is still a slight hum when the output volume is all the way down.  However,  once I turn up the output volume knob,  it's not really noticable.  :grin:  I realize there should be no hum at all but at this point I don't know what else to try.
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 12, 2004, 07:04:44 AM
Hi all, I just builded a g1176 with a Gustav board. The voltages on signal line amp all all very close to schem values. But I have problems in GR control amp. the 30.3V are ok but the other values on Q12 Q13 Q14 and Q15 are wrong, all are slower. The 27.8V next to 30.3V is 17.7v only, and the voltage next to C17 (next point 22) is only 3.1. I test the NPNs with diode function and they seems to be ok, I checked the values of Resistences, the color codes, and they are all ok too (I think). Can a transistor be broken? o a res burn out?... argggghh!! oks... I continue testing it...

That post its cool  :grin: , but i cant find a similar problem
Thanks :)

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 12, 2004, 07:51:51 AM
:oops:  sorry... looking at board i find that i put C18 (47uF) reversed....  :oops:  I changed it and now im looking for voltages, but they seem to be ok for the moment...  im very happy for the moment :)
Thanks

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: SSLtech on August 12, 2004, 12:01:44 PM
Gnaaaaaargh!

-My first 1176 is kicking my butt...! Q3 is saturating. If I remove it, the collector goes up tp 19V or so. If I put it in then it goes down to about 1.1V. It drops below the Base voltage!

I've removed Q4, still the same. -If everything was working correctly (as I read it) I should be able to remove Q4 and see a correct waveform at the base... -is that correct?

(This is a Purple Audio MC76 board, but the circuit is esentially the same in this region)

The voltages are:

..B...|..C...|...E...
0.8V  1.6V  0.3V (Q2)
1.6V  1.1V  0.9V (Q3)

Obviously, Q3 is saturating, with about 0.65V from base-to-emitter. All the resistors on the base end look correct though. I'm baffled! I can't see why this is the case... :?:

Keith
Title: All things G1176 - the new "repost" thread.
Post by: SSLtech on August 12, 2004, 05:11:27 PM
Problem solved. there was a wrong value resistor in one place... shoulda been 180 ohms... 108K will reallly mess things up!
:wink:

keith
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on August 12, 2004, 10:37:54 PM
Gosh!!  Those picky resistors...i mean 180 and 108 both have a "1","0" and an "8"...what more could it want?!  :)  hehehe I crack myself up.

Glad you fixed that issue.  I cannot wait to see it completed!!

Lata,
Michael

P.S.  Tighten down the hatches...Charley is on his way...
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 13, 2004, 05:11:28 AM
Hi all, my 1176 clone is builded... all seems to be ok, now i must calibrate it and for the moment i havent the sifam AL29 VU meters.  I supose that I can calibrate it with a osciloscope, cant I? But i dont remember the equivalences of 0Vu, 1Vu and voltage amplitude with a signal generator. Can I calibrate with a sin generator and a 2ch osc, can somebody tell me how?
and... would be more precise an osciloscope calibration than one with the vu meter?
 :?:
thanks  :grin:

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 13, 2004, 08:40:27 AM
hi!

i just completed a g1176 with one of gustavs boards

and roundabout everything seems to be working... :)

but since I never worked with one of the originals
here are some questions :

( i have no meter , so I have not done the calibration process yet!)

1)
in bypass mode I have to open the input and output pot
so that the unit passes audio, is that correct?
(unit does not pass audio with in/output pots counterclockwise!)

2) in compression mode when switching from 4:1 to 8:1
output level drops a little (as I would expect it to do)

but when switching from 8:1 to    12:1 or 20:1
my output increases about 6-8dB
(and i think it does not compress in those modes!!?? no noticable difference when switching to bypass during 12:1 or 20:1 mode)

so iam guessing that maybe i programmed the ratio switch lorlin wrong??!! would that explain that behaviour???)


i finished an ssl clone so far and it worked right from the
bench, my electronics knowledge is limited to none
so i cant follow the ratio switch schematic...sorry


the hum issue:

well there is hum down there, but i have not added the
extra groundplane reinforcement thing yet.

the hum absolutely disappears at 12´o clock setting
of the output pot on my unit.

it is the loudest CW!


christian
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 13, 2004, 09:02:08 AM
ooops!

i just saw, that I forgot two solder joints on the ratio switch board
 connecting the 12:1 and 20:1 lorlin connection to the board
itself....:)

hmm
second project seems to be finished and working right
off the bench, i am amazed
metalwork coming up (hate it)

thanks jakob for those diy projects.

hope I can decrease the hum a little...

thanks

christian
Title: All things G1176 - the new "repost" thread.
Post by: SSLtech on August 13, 2004, 09:48:26 AM
The 'bypass' in the original does not bypass the audio circuitry, it merely disables the gain reduction. I think that the Gyraf version is similar in this respect, so your 'bypass' description sounds normal.

Keith
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 13, 2004, 07:56:37 PM
regarding the hum/ground problems on the gyraf layout. has anyone tried cutting the ground trace at one point so that it is not a continuous loop around the perimeter as per mnats layout?

i'm anxious to get started on my G1176, but i was hoping/waiting to see if Gustav would get the gerbers for mnats' layout, as it seems to address many of the problems builders are having...including the BD135/136 pinout  flip. has anyone etched one?

also, i got some of the parts in today. i ordered some orange drops for the polyprops to try out and the 1uF is quite big. i test fit it on the layout and it seems to be ok. what are most others using? i've seen some parts list with panasonic ECG series. any comments as to sonic characteristics of the options for the polyprops?

i also decided to try out a BUD case. i think it's great. a simple no nonsense product and the front panel seems like it will be easily workable.  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 13, 2004, 08:49:46 PM
>regarding the hum/ground problems on the gyraf layout. has anyone tried cutting the ground trace at one point so that it is not a continuous loop....
                                                     

thought about the same thing
and it´ s the first thing i am going to check out this weekend
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 13, 2004, 11:15:22 PM
I'm confused about the power transformer - the parts list has a 12-0-12V transformer listed, unless I misread it, and the board calls for 24-0-24V. Which do you use in the 120V part of the world? Also, how many VA does it need to be rated for?

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 14, 2004, 02:43:25 AM
Quote from: "romeojesus"
>regarding the hum/ground problems on the gyraf layout. has anyone tried cutting the ground trace at one point so that it is not a continuous loop....
                                                     

thought about the same thing
and it´ s the first thing i am going to check out this weekend


Let us know how that turns out, Romeojesus.  I am thinking about trying this too.  In the other thread regarding the updated version of the G1176 PCB,  this was posted:

   
Quote
" Another is adding additional grounding pads to accommodate the shields of the various wires going from the board to the controls (part of the reason why my clone has virtually no audible hum at any reasonable levels also has to do with the wiring, I believe)".


   I bought a roll of shielded multicable for all of my projects.  Inside of it there is  metal braided wire without wrapping.  I assume this is the "shield/ground"?   I should  connect this to the grounding pads from the pot.  Am I understanding this correctly?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2004, 04:38:19 AM
Romeojesus, Al_p, and Orson,

Yes, cutting the ground at one point will probably help a lot. Only haven't I had the time to find the right spot for the surgery yet.

My guess would be to cut just after the output stage (when seeing it from the PSU section:

EDIT: This is now pointing to Christian's suggested cut...

(http://www.gyraf.dk/tmp/1176_ground_edit_idea.gif)


EDIT: This is now pointing to Christian's suggested cut...

Please let me know what you find out!

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 14, 2004, 06:05:14 AM
ok, just cut the ground plane on jakob´ suggested position....

this turns down the hum A LOT...really

there still is some hum down there
but now increasing the output
pot hasn´ impact on the volume of the hum anymore (like it did before)

maybe the rest of the hum comes from the fact that my unit
has no case yet. it is sitting on a record sleeve and the iec
power connection is not grounded yet etc etc


christian
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2004, 06:53:50 AM
Thanks Christian,

It seems that this is a good way to go. Would be interesting to know how your unit behaves when cased and grounded.

Do you have enforced ground around the board as well?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 14, 2004, 07:15:42 AM
no..no ground enforcement yet...
but i am going to add that, too!

christian
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 14, 2004, 08:05:56 AM
Hi guys :). My unit seems to run all ok (exept vumeters that i havent yet). Im trying to find the better place for the toroid with no hum. I put on with IN and OUT full CW, without signal IN. Im scoping the output signal direct to my scope. I only see a small signal of 100Hz with a 25mV positive periode of 2ms, and 10mV of  500 KHz hig frecuencies. When I move the toroid arround the signal stays without changes... Its that ok? or I must put in some signal to view the hum problems? i never did a test of that and I dont know how I can do it exactly....   :?

Thanks

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2004, 08:10:27 AM
You will find VERY little difference in hum when moving the toroid transformer around. The trick with moving powersupply transformers around is for standard EI-core transformers that has way higher stray field.

Somewhere here there is a thread about this topic..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 14, 2004, 08:16:40 AM
ahh...! thanks Jacob  :grin:  i look for that thread... I supose that I can place the toroid where I like without diference with hum, cant I?
thanks

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2004, 08:35:27 AM
yep - but still keep it as far away from the pcb as possible..
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 14, 2004, 11:43:44 AM
Quote from: "romeojesus"
this turns down the hum A LOT...really


cool. thanks for trying that. :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 14, 2004, 11:46:42 AM
hi,

I've just completed a G1176 and no problems .

  I'm using a 1:1 output tranny and getting my +4 output level with the output control in the top 30% of it's adjustment.

There is a hum though.

  I'd like to try the cut that Christian did.I'm wondering,
 what are the best methods of cutting the trace?

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 14, 2004, 12:27:55 PM
When cutting the ground trace should the reinforced ground wire be cut as well at the same place?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2004, 12:49:16 PM
Seth,

Yes.

Cut the ground at the same spot as the PCB.
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 14, 2004, 01:16:32 PM
Thanks, Jakob.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 14, 2004, 02:13:28 PM
I decided to try a cut of the trace in a different spot.

My idea was to distance the output transformer ground from the power supply and keep it tied to the input/output cables.

1) cut trace at small point under C15 (cap to in of output tranny)

2) cut on an angle near pin 3 con of output tranny past pins 4&5 to edge
of board leaving equal meat of ground plane each side of cut.

so the ground point of tranny is not close to PS

Result is very quiet. The hiss is far louder than hum.
If I turn up output to full, I still can't really hear a hum .
I have to max my IN fader and Master fader (of console) to hear a 60 cycle hum.

I could see that if I was to properly install this into a box it could be pretty much dead quiet.

BTW I have not connected shields on in/out cables or reinforced the ground plane with the 14 guage wire.

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2004, 04:20:55 PM
Lance,

Good!

Would it be possible for you to post a drawing of the points in question?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 14, 2004, 04:40:40 PM
hi Jakob , I just responded to you in the other thread. maybe we should

drop the other thread?

I only have graphics of the board in a PDF.
If you direct me to a pic I'll give it a try.

Lance
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 14, 2004, 05:16:56 PM
found one...drew the cuts but I don't know how to post it :?

Lance
Title: All things G1176 - the new "repost" thread.
Post by: daArry on August 14, 2004, 06:17:32 PM
lance, if u email me it I'll host n post here...
Title: Lance GND modifikation
Post by: stoff on August 14, 2004, 06:58:57 PM
This is my first post here on the new Lab...
I have built 4pcs. of G1176. All work fine since the first time powering up!
@ this point I would like to say MANY THANKS to Jakob and all Others for this greate project  :thumb:
However all 4pcs. has the hum problem. I was a little bit fustrated. After along time to try different GND solution without sugcess is this solution!!

   
Quote

from Lance:
1) cut trace at small point under C15 (cap to in of output tranny)

2) cut on an angle near pin 3 con of output tranny past pins 4&5 to edge
of board leaving equal meat of ground plane each side of cut.

Now I have 200% NO  hum!!!!!! :grin:
I can high recommend this GND solution!!!

I have also the shields on I/O cables floated and the reinforced the ground plane with the 14 guage wire is done.

I'm so happy now  :grin:  Jupiee!
thanks to all
Stoff
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 14, 2004, 07:32:21 PM
3rd time lucky

(http://www.geocities.com/pepperplace/rev_7_cuts.jpg)

now I need a drink,

cheers, :sam:  :guinness:  :sam:

Lance
Title: All things G1176 - the new "repost" thread.
Post by: stoff on August 14, 2004, 07:39:37 PM
thanks Lance! :thumb:

You are the MAN OF THE DAY or better YEAR!!
take a drink of my bill
 :guinness: cheers :sam:
Grz stoff
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 14, 2004, 08:04:34 PM
good work guys.
 :green:  :sam:  :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 14, 2004, 09:11:39 PM
stoff, thanks for giving the cuts a test.

daAry, good of you to offer hosting,thanks. But it was time for me to learn how to post a pic.


Jakob,  could we try revision #8 with ;

1) pin chages for BD 139/140 type outputs

2)grnd trace cut ,location(s) of your choice

3)maybe most people want the out tranny reworked for 1:2.
 I'm good with the way it is.
(I  have a 1:1 in place and will likely try out the original 2:1 )

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: tubejay on August 14, 2004, 09:33:50 PM
Quote from: "jrmintz"
I'm confused about the power transformer - the parts list has a 12-0-12V transformer listed, unless I misread it, and the board calls for 24-0-24V. Which do you use in the 120V part of the world? Also, how many VA does it need to be rated for?

Thanks


Anyone have an answer to this?  I'm about to place my order with this part on it, and just happened to notice the same thing!  Which should it be 24 or 12?  Oh, and I'm 120v too.

Thanks,

Jay
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 14, 2004, 10:16:37 PM
Jay, Seth:
Quote
jrmintz wrote:
I'm confused about the power transformer - the parts list has a 12-0-12V transformer listed, unless I misread it, and the board calls for 24-0-24V. Which do you use in the 120V part of the world? Also, how many VA does it need to be rated for?

Thanks


Anyone have an answer to this? I'm about to place my order with this part on it, and just happened to notice the same thing! Which should it be 24 or 12? Oh, and I'm 120v too.

Thanks,

Jay
Order: 24-0-24/500mA(24VA) This is on the 1176 parts list at the Gyraf site.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 14, 2004, 10:48:32 PM
Thanks, Dean. I have a 24-0-24 toroid that's 350 mA per secondary. Is that likely to be big enough? I suppose I can ty it and see if the voltages are correct.

BTW, I know the source of my confusion. I downloaded a parts list somewhere that is the Gyraf list with part numbers from Mouser and Digi-Key added. Someone obviously did a lot of research, which I thank them for sharing, but the transformer on that list is a 12-0-12V part number, I think. So if anyone else has that parts list please be careful to double-check it.
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 15, 2004, 06:05:51 AM
ok status report!

after doing the cut jakob suggested, I was curious about
the improvement hitchhiker achieved with his
cutting spots.

so this morning I bridges the "JAKOB" cut
and did the "hitchhiker cut"

but accidentally I did not cut betwwen the 2&3 pin of the
output trannie , but between 3&4 (meaning: cut is one
pin closer to the edge than hitchhikers one)

result:

unit is DEAD QUIET......AND WORKING!!!

no hum at all, I cranked up my mixing board, its main volume fader
and my amplifier to the max....

no hum!!

it seems like humwise this thing turns out to be one of my quietest
units , just compared it with my bss dpr402

keep in mind that i don´ have the groundplane reinforcement...

i guess i can HIGHLY recommend that cut!



i am really happy now..thanks everybody
little sad though because the down side of the pcb looks
a little ugly, but who cares.....this thing is great...



christian
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 15, 2004, 07:31:30 AM
So now we are all curious if you, Romeojesus,  know how to post a pic too? :green:   If so would you be so kind to post a pic of exactly where you made the accidental cut that rocks and rolls and gives No Hum! :thumb:  :thumb:  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 15, 2004, 07:43:17 AM
Good work, Christian!

 :thumb:

Could you make us a drawing of the cut point?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 15, 2004, 07:58:46 AM
dont know how to post pics
i´ll send a pic to gyraf


some statistics:

i am running unbalanced
all connections to input/output/attack/release pots via microphone cable
gustavs boards
no groundplane reinforcement
not cased yet

christian[/img]
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 15, 2004, 08:31:53 AM
Here's Christian's edit suggestion:

(http://www.gyraf.dk/tmp/1176_ground_edit_idea.gif)

Please let me know if this working for you also..!

Jakob E.
Title: A strange thing!
Post by: xsmsx on August 15, 2004, 09:48:00 AM
Hi there,

I just recognized the new PCB layout and I will try this solution as soon as I got some help for another problem. I built two units. One works fine, but the other doesn't. Maybe anyone has a solution idea for this:

The unit seems to work only in bypass. The meter switch seems to be out of order BUT the Release pot turns down the level when turned into the right direction. Also the unit seems to make much more level at the same Input and Output positions compared to the other unit.

Any suggestions anyone?

Thanks
Christoph
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 15, 2004, 09:59:35 AM
Christoph,

- check for shorts.
- check for correct components (AND orientation!)
- check wireing
- compare DC and AC voltages between working and non-working units - specially in the sidechain/rectifier stages

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 15, 2004, 02:12:02 PM
good work Christian,

I think this ties the core and can of the transformer to the power supply
ground.

Are you reversing your transformer? If so, does it still work out that the can & core are wired to hole 3?

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 15, 2004, 07:00:04 PM
no, my output transformer is not reversed
it´s 2:1 like the original hookup on www.gyraf.dk
and i am using the 5532 input

after playing around with it today I do not
feel the need for extra output gain

that jufgement is based on
the fact that my unit is not calibrated yet, due to the fact
that I am lacking a vu meter..

we´ll see...

christian
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 15, 2004, 07:43:37 PM
hi Christian,

cool, thanks for the reply.I have not studied the recomended flip directions
of the output tranny but I would imagine they keep the core & can on
#3 pad.

I hooked up my can to the power supply side of the cut and I think there's still a hum way down there but too low to know if theres any difference from my original cut and wiring.

I'm using a different tranny so yours is the test that counts the most.

My hiss is plenty there . Did you use metal resitors or carbon?
I'm wondering if I'll get a noticable improvement if I order metal for my next units?

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 15, 2004, 09:29:40 PM
Seth,
Quote
I have a 24-0-24 toroid that's 350 mA per secondary. Is that likely to be big enough?
I measured the total current draw for one channel, including the sifam meter lamp, and it is ~200mA at the most.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 15, 2004, 10:03:56 PM
Thanks, Dean. Much appreciated. It's almost ready to fire up - just need to get the chassis.

 :sam:
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 16, 2004, 05:16:05 AM
hi hitchhiker..

i don´ really understand what you mean by "can"!!??


my unit has some hiss too (depending
on in/output pot setting), but i think thats the units
characteristic and it doesn´t bother me at all
the hum was way more annoying
(more hiss than my vca design based compressors)


i am using metal resistors, panasonic fc caps and wima polys throughout!

christian
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 17, 2004, 01:11:24 PM
ABSOLUTELY EXCELLENT NEWS TO REPORT! :!:  "Bye, Bye, hum.  Bye, Bye, hummy hum.  Hello si-i-lence.  I think I'm gonna cry-hi".
  The G1176 is almost completely quiet now. W- o- w ! !   :green:  :sam:  :guinness:  :thumb:  :grin:  :cool:  :razz:
Christian's (Romeojesus) cuts did the trick.  I think I need to get rid of the jumpers between my two Xlr's to get rid of the very little hum thats present when the input volume is turned al the way CCW. But now it's really ok the way it is.  I am very happy.  
Quote from: "romeojesus"
 my unit has some hiss too (depending
on in/output pot setting), but i think thats the units
characteristic and it doesn´t bother me at all
the hum was way more annoying
(more hiss than my vca design based compressors)
I totally agree!  I am however going to build the next one without the modification to increase 12dB's.  I am curious to see if I really need it and if this hiss decreases a bit but it really doesn't bother me at all.  I remember at high settings my 1064 was hissy too.    Thank you Romeojesus.  Jakob, Dean, I can finally close the lid on this baby.   You two are very helpful and generous with your time.  I very much appreciate your help as well as Johnathan Hayward and Mark Burnley and many others.   Thanks guys,  you and this place rocks.  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 17, 2004, 01:41:34 PM
what's the perfered method of powering 2 channels of G1176 in one box?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 17, 2004, 02:50:31 PM
al-p,
Quote
what's the perfered method of powering 2 channels of G1176 in one box?
Well, I used a single power transformer rated for [email protected] that feeds two complete G1176 boards in parallel. This is easy and works great. The regulated PSU circuits on each board decouple the two channels very well. Even with the boards stacked atop one another with 1/2" of clearance the crosstalk is zero.


Dean
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on August 17, 2004, 06:35:12 PM
>"Bye, Bye, hum. Bye, Bye, hummy hum. Hello si-i-lence. I think I'm gonna cry-hi"

good to hear that this cut turned out to be helpful
on other peoples unit as well (orson)

and after building a ssl clone and g1176 it
also feels good to know that I contributed
something useful to this great forum (based
on hitchhiker idea and by accident)

>I think I'm gonna cry-hi
...that´s how I felt after noticing the hum was gone...

happy compressing...


christian
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 17, 2004, 09:38:42 PM
well I beleive it was al_p that came up with the idea to cut the ground trace perimiter.many  thanks for sharing your idea al_p! :sam:  :guinness:  :thumb:

hi Orson , Did un-linking your XLR's get the last of the hum?

The only way to know which cut gets the quietest result is to A/B/C etc them very critically side by side. (dead quiet audition chain required)

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 17, 2004, 10:10:39 PM
Out of curiosity I eliminated the  grounded jumper connected between both XLR's with no difference.
I connected the perimeter wire to star ground with no difference either.
Using a computer is not the best way to test for hum :roll: .  It's inherent atleast in mine.  Increasing mic-pre input gain dramatically lowers G1176 output hiss because it's input volume does not need to be as high.  Common sense,  I know but I overlooked that before.   Just thought I'd share so people know what can and doesn't make a difference in ground loop hum and natural hiss.
I noticed high mic-pre output equals a lower g1176 input setting and a difference in sound.  I liked it better when the mic-pre was low and the G1176 input was high.  Even though the hiss increases so does something else.  It just sounded better, sweeter to my ears.  Just my 2 cents.  Carry on.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 17, 2004, 10:30:48 PM
hi orson,

You could try the cut I posted on page 20. It  may be worth it or may change nothing but I don't think it will make the hum worse.

It would involve jumping pin3 to the pin 4 side and cutting off pin 3 from
the power supply side.

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 17, 2004, 10:39:25 PM
OK  I will try that manana and then post the results.  Isn't there another cut we can make somewhere?  I ask this becasue someone made a new PCB design with several different sections of ground trace.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 17, 2004, 10:46:17 PM
I havn't been following every page of this thread so I can't confirm that
version. One cut at a time might be good at this point anyway.

There is so many variables as it is.....

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 17, 2004, 10:58:01 PM
http://www.groupdiy.com/index.php?topic=1409

Check the link on the first page by Matthias    http://www.geocities.com/m_natsume/1176.html

on his site he proposes a newer design and if you scroll down to around half of the page you can click on a link that will show you a new PCB layout with red tracing the grounds.  I know you must have seen this.  What I meant before was isn't there another cut we can make BESIDES / IN ADDITION to the ones we already are doing.  I don't want to beat this to death but Romeojesus ( Christian) sounds like he has absolutely zero hum.  Mine is more like what you describe.  BUT I am being anal retentive for sure.  Right now I am very happy with the way my G'76 is performing.  No doubt!
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 17, 2004, 11:24:49 PM
hi Orson,

the reason for me thinking it might be worth trying this one cut first is
that (just before my picture of the cut, stoff followed my written description)stoff reports dead quiet with the cut I suggested and then we had the report of Christians accidental change in the cut.

The hum on my unit is so far down it's more like a ghost of a hum.
When I change my inputs and outputs it does not increase. It's so close to dead quiet that I think if I was using the lundhal tranny it may be gone.
From what you described I think your hum may be stronger?

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 18, 2004, 12:27:04 AM
I just found the rev E that mnats did that shows the red perimiter cut beside the input transformer. I think all the rest of the ground is connected.I couldn't find one with 3 cuts.

mnat's new boards (rev F I believe) are gonna be great .But even still I hope we can find a simple solution for this layout. Gyraf, Kev and others
have done so much to get it this far.

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: mnats on August 18, 2004, 04:22:40 AM
Quote
But even still I hope we can find a simple solution for this layout. Gyraf, Kev and others
have done so much to get it this far.

Agreed. My version isn't meant to be a replacement, just another version with modifications I thought were common and useful. You'll still want Jakob's original board if you want to use the BD517/518 output transistors and the Lundahl wired 2:1.
Quote
Check the link on the first page by Matthias http://www.geocities.com/m_natsume/1176.html

Not to toot my own horn or anything but that's my page, not Matthias'. Check the New G1176 design ? thread for progress on the new board and please register your opinions on rotary vs pushbutton switches.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 18, 2004, 08:32:53 AM
Quote from: "hitchhiker"
hi Orson,

the reason for me thinking it might be worth trying this one cut first is
that (just before my picture of the cut, stoff followed my written description)stoff reports dead quiet with the cut I suggested and then we had the report of Christians accidental change in the cut.
The hum on my unit is so far down it's more like a ghost of a hum.
When I change my inputs and outputs it does not increase. It's so close to dead quiet that I think if I was using the lundhal tranny it may be gone.
From what you described I think your hum may be stronger?
cheers,
Lance


The hum is completely gone.   :shock: This unit is now 100% quiet.  :shock:  THanks for encouraging me to try it.  I almost left things ass they were.   :green:  :thumb:  :sam:  :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 18, 2004, 08:36:06 AM
EDIT:

So the current fully-working cut is Hitchhikers cut:

(http://www.geocities.com/pepperplace/rev_7_cuts.jpg)

Is this correct?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on August 18, 2004, 09:11:37 AM
Yes this is the one that works for me.  It renders zero hum in my unit.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 18, 2004, 10:44:58 AM
good going Orson,

cheers,
Lance
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 18, 2004, 11:47:24 AM
I wanted to mention that I used PRR's jig to match FETs, and it works like a charm - I found two within .01 VDC. Thanks to PRR for that simple and elegant design.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 18, 2004, 11:53:32 AM
Seth,

Could you post a link to that?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: hitchhiker on August 18, 2004, 11:59:19 AM
yes Seth ,

I used PRR's circuit as well.Works great.I was wondering if higher values are better or what? Most of my matches fell between 6 & 8 volts.

Lance
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on August 19, 2004, 01:40:43 AM
Quote from: "gyraf"
Seth,
Could you post a link to that?
Jakob E.


Jakob,

With pleasure:

(http://sethglassman.com/PRRFET-sort.gif)

Quote
I was wondering if higher values are better or what? Most of my matches fell between 6 & 8 volts.


Lance,

Most of my matches were in the same range and I was wondering the same thing. Does anybody know what absolute values would work best?

 :thumb:  :thumb:  :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 19, 2004, 03:34:13 AM
Would be easy to mount an original urei fet in a contraption like that, to find the ultimate reference value.. unfortunately all our 1176's are racked up and in use for the next month or so..
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 19, 2004, 07:30:13 PM
Hi to all  :wink: , I have the sifam vumeters now  :grin: . But I have problems... I wire the vumeter and now im doing the adjustments. I have some problems with them. The Qvias no problem... but when I try to adjust the tracking pot I can reach the 6dv of gain reduction. I put the signal in adjust the in and out for a unity gain and then i up the input until I have the output at half of input, the vumeter in Gain reduction mode reads only -1 and when i try to turn the track trim its imposible to reach the -6dv...
I dont know why, now im looking components searching errors. ..
Another thing. 0 VU is aprox 0.75 Vrms, arent it?. When I have 0VU on the meter I read something like 1.3 Vrms at output.... is that possible? im very confused with all these.
Oks.. thanks all for that nice Forum :grin:

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 19, 2004, 11:55:28 PM
Hi Arnau,
Quote
Another thing. 0 VU is aprox 0.75 Vrms, arent it?. When I have 0VU on the meter I read something like 1.3 Vrms at output.... is that possible?.
That is normal. The 0 VU is referenced to +4db.

0db=.775V
+4db= 1.23V
Quote
The Qvias no problem... but when I try to adjust the tracking pot I can reach the 6dv of gain reduction. I put the signal in adjust the in and out for a unity gain and then i up the input until I have the output at half of input, the vumeter in Gain reduction mode reads only -1 and when i try to turn the track trim its imposible to reach the -6dv...
This adjustment can be tricky, especially when Q1 & Q10 are not well matched in terms of their cutoff voltage.

You have to carefully work the meter track and meter zero trimpots against each other in small steps until things work out. This may include experimenting by starting the adjustment with each trimmer in a different point in rotation relative to the other; that is, start with one full CW and the other full CCW and see if that helps. If not, try the opposite. Sneak up on it.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: shmuu102 on August 20, 2004, 12:47:33 AM
Im having a problem with my 1176 that maybe someone could help with..

the release knob acts like a second output volume knob.... even in bypass.


i have replaced both fairchild diodes.. checked all the wires, pcb.. voltages on the transistors seems "close" to what everyone else is getting. nothing so far has seemed to help...  anyone got any suggestions are where i should look next ( what parts i should start "hanging")?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on August 20, 2004, 01:42:31 AM
Quote
the release knob acts like a second output volume knob.... even in bypass.
It sounds like the release pot is changing your Qbias voltage. Measure DCV between the release pot wiper and ground while turning the release control to see what the voltage does. It should stay around -2Vdc, varying only a tiny bit.

I suspect that you have a component or wiring error surrounding and or including the release pot. Look at the schematic when checking.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 20, 2004, 08:55:13 AM
Thanks Dean! I do like you said and I calibrate it  :grin:  its a little complicated, yes.... I found that its more easy (to me) starting with zero meter pot CW and track CCW. I adjust the point of 6db reduction with zero trimer and next the 0vu with the track trimer... doing that operation iteratively I reach the correct adjust.... Now I must look at ratio switch, I have problems with it (like it is reverse), Im in it

Thanks!!

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 28, 2004, 03:01:52 PM
Hi to all. My unit seems to work correct, not much hum, but im not sure of what is a low hum and what isnt tolerable...
I rotate the ratio switch and I cant see more ore less compressión (looking GR in meter). How can I be sure that the ratio compressíon switch is working correct? I thinked that I saw a double gain reduction if I pass from 1:4 to 1:8... but I cant see that diference... it maintains the same ratio, well... it changes for a moment but then it returns in the same reduction than before (seems to be a cap charge... i dont know).
How you block the last two positions of ratio switch? or simply dont rotate it more than the 4 first positions?
Thanks!

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 29, 2004, 07:16:12 AM
Arnau,

You "program" the lorlin switches by lifting and rotating the stopper pin that is located under the mounting nut.

The ratio switch also changes the threshold, so you will have approx. the same GR at different ratios. Your unit seems to act normal.

We've covered this either earlier in this thread, or in another thread. Be sure to read through it all:

http://www.groupdiy.com/index.php?topic=155

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Apache5 on August 29, 2004, 04:27:41 PM
:grin:  I suspected something like these on the ratio function but I must  to be sure... thanks Jacob. About Lorlin programation... yes, sorry, these that you say sounds me... I must read more acurately.  Thanks again  :wink:
I must take pics and post it because now I think that is finished... and its my first DIY project :) (and not the last, im sure).

Arnau
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on August 31, 2004, 04:22:57 PM
Would a linear pot on the input gain cause it to:

A. have less gain than a log pot at a lower number (Counter clockwise)

or

B. have more gain than a log pot at a lower number

I'm asking because I'm thinking I may have a linear pot in there by accident, and I want to know if I replaced it with a log pot if I would be able to turn up the input more before the threshold would be reached.

Thanks

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 31, 2004, 11:51:47 PM
hi

i'm putting 2 G1176s in one box. [8" deep] with my meters, i'd have to either mount them atop one another, or side by side lengthwise, which would bring the output tranny of channel 2 less than an inch and a half away from the toroid. the other config i was thinking about was mounting the power transformer on the back leaving plenty of room to tweak the positions of the mainboards.

i know dean has had good luck with the stacked boards, but i'd like to have easy access to all the cal points. so what do you guys think? will i be OK that close to the toroid? or should i go for a rear mounted power tranny. if so would a non-toroidal [lets say a hammond 167J50 cause i have one here...] work fine?

thanks
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on September 03, 2004, 03:21:27 PM
My Vu meter is hovering.  (Sifam AL-29) The unit is working though.  It compresses very nicely.  Sometimes, it hovers dramatically as if there was a ghost singing into the mic at a loud volume.  It hovers back and forth not just down.  This happens only when it's in GR mode.  All the other pots can be at any setting and it still occurs as long as the GR mode is selected.  Even with the volume pots fully CCW it happens.  When I am singing and it start going crazy my voice sounds perfect.  It's as though the meter is not reflecting fully whats going on in reality.  If it hovers while I am singing into the mic,  it registers the compression but still dances around while doing so.
Sometimes this behavior stops for a while.  I can't find a pattern to it.  If I had to though,  I would assume this happens only after the unit has been on for a while.  I should really test this out to see if it happens consistently after a certain amount of time but I haven't gotten around to doing this yet.
What is causing this behavior?
Title: All things G1176 - the new "repost" thread.
Post by: Gustav on September 03, 2004, 05:19:53 PM
Making only one panel at a time now of the G1176, and almost out again. Anyone up for doing the working cut in the gerber ?

Gustav
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 04, 2004, 07:03:53 AM
Gustav,

I'm working on it. I'll get it ready in a week or so, I hope.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on September 04, 2004, 11:31:32 AM
Orson,
Quote
My Vu meter is hovering. (Sifam AL-29) The unit is working though. It compresses very nicely. Sometimes, it hovers dramatically as if there was a ghost singing into the mic at a loud volume. It hovers back and forth not just down. This happens only when it's in GR mode. All the other pots can be at any setting and it still occurs as long as the GR mode is selected. Even with the volume pots fully CCW it happens. When I am singing and it start going crazy my voice sounds perfect. It's as though the meter is not reflecting fully whats going on in reality. If it hovers while I am singing into the mic, it registers the compression but still dances around while doing so.
Sometimes this behavior stops for a while. I can't find a pattern to it. If I had to though, I would assume this happens only after the unit has been on for a while. I should really test this out to see if it happens consistently after a certain amount of time but I haven't gotten around to doing this yet.
What is causing this behavior?


Is this something that has come up recently? I had a similar problem at different times on both of my channels. I noticed that touching the diode in the GR Meter Amp(CR11) with a little pressure caused the needle to fall down and jump back up even more. Replacing the diode fixed the problem. I think I may have fractured the diode by jerking it down onto the PCB, or I overheated it while soldering. Now it floats off the board 1/8" or so.

You might replace the TL071 as well just to rule it out.

Dean
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 04, 2004, 11:37:28 AM
Also dirt/moisture around the meter FET can cause the meter to behave strange. Try cleaning the area around it with a bit of isopropyl alcohol..

kdawg,

A linear pot will be 50% down (-6dB) at centre position. A log pot will be 80% (-12dB) down at centre

Jakob E.
Title: 1176 - Grounding & Transformer Mod(output levels)
Post by: thedug on September 04, 2004, 01:59:02 PM
Hey,

I remember that the thread over at Tech Talk had some instructions on Grounding & Transformer Mods.

Does anyone have those?

If they are somewhere in this thread, just let me know.

d./
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 04, 2004, 02:03:18 PM
Dug,

See the "meta" for the 1176 project, found in the sticky "meta-meta" on the top of the first page in this forum:

http://www.groupdiy.com/index.php?topic=1277

Jakob E.
Title: Transformer
Post by: keithcamilleri on September 13, 2004, 03:13:17 AM
Hi Guys,

Can anyone help me on the toroid transformer I found this one from jaycar but I don't know if it wokrs on the G1176... the product number is MT2114.

The pots are another problem it seems that I cannot find audio taper can anyone help me out on these as well....


Regards
Title: BD517 & BD518
Post by: keithcamilleri on September 13, 2004, 06:46:24 AM
If anyone is looking for the BD517 & BD518 ....you can find these here

http://www.fibra-brandt.com

they have them in stock about 2.70 euros. each...
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on September 13, 2004, 06:48:36 AM
hmm!

finally my sifam vu meter arrived from meterdistributor.com

it came with the wrong bezel :(

plus the meter seems to be broken....

i have voltage across m+ and m- on the
1176 meter pcb, but the meter does
not react in any way... :(

somebody have a hint??

thanks

christian
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on September 13, 2004, 06:57:27 AM
Quote
i have voltage across m+ and m- on the
1176 meter pcb, but the meter does
not react in any way... :(


That is correct because the meter has a bridge rectifier in it so that it will react in only one direction to an AC signal, which is what you are feeding it.   If you have the facility to hook it up to an audio output (maybe a CD player in series with a 3K6 resistor you should find that it works !
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on September 13, 2004, 07:15:02 AM
ok...try to help me out here ,please..

i have a voltage on m+/m-
value depends on unit bypassed (0)
or in gain reduction mode and adjustments of
gr pot and tracking pots on pcb...

so on this side everything seems to be ok...

but there is no vu movement no matter
what m+/m- polarity


??
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on September 13, 2004, 07:23:27 AM
Quote
i have a voltage on m+/m-
value depends on unit bypassed (0)
or in gain reduction mode and adjustments of
gr pot and tracking pots on pcb...


The easy way to check whether you have a faulty meter is to check it out of this circuit like I said in the previous post.   If it works when you you hook it up to maybe a CD player, then you know you have a fault with the 1176.

Does your 1176 pass a signal?   If you have the meter switch set to output then the meter is just connected to the output of the 1176.  If the 1176 is passing audio & you have proved the meter to work out of this circuit then it is likely that you have a problem with the meter selection/bypass board of wiring.

In gain reduction mode the mater action is affected by all the things you said, but also the FET byass adjustment.
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on September 13, 2004, 08:08:28 AM
my g1176 works good so far and seems to be ok!

i connected the vu to the headphone out of my
amp and cranked it up....

vu meter does not move :(
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on September 13, 2004, 08:23:18 AM
Quote
i connected the vu to the headphone out of my
amp and cranked it up....

vu meter does not move :(


Then I think you do need a new VU meter !
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on September 13, 2004, 09:20:27 AM
sh*t...

thanks for your help!
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 15, 2004, 04:16:10 PM
Hi Everyone,

I fired up my 1176 and no joy. I only seem to have signal as far as the base of Q2, and odd voltages as follows:

Q2:
E .102
B .098
C .818

Q3:
E .189
B .818
C .255

Q4:
E .109
B .255
C 30.4

Also, the empty 5532 socket has +15.2 on pin 3, +15.2 on pin 5, and +30.4 on pin 8. All the others have 0. That's not right, is it? I've measured resistors around this area and they seem OK, and I changed Q2 but that's not it. The unit is not passing signal and starts to oscillate on the highest input voltage setting. Does all of this point to anything?

I have to go now, so I don't have time to get more voltage measurements, but I will later.

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 16, 2004, 01:03:13 PM
*Bump*
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 17, 2004, 02:55:36 AM
Seth,

- check supply voltage after R17 - should be some 25V
- double check for component values (spec. R17 - 6.8K / R18 - 22K)
- double check for pcb shorts
- check Q2-3-4

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 17, 2004, 10:26:27 AM
Thanks Jakob

 :thumb:
Title: Capacitor
Post by: keithcamilleri on September 19, 2004, 05:57:04 AM
Hi JaKOB,

on the G1176 PCB there is a capacitor just before the Trafo outpu it is a 470uf ....on the PCB layout it printed as a 40V cap (the list said 35v), I used a 35v audigrade cap is that ok?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 19, 2004, 06:09:33 AM
35V is fine for the output cap. There'll never be more than 30V across it anyway.
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on September 19, 2004, 06:26:17 AM
thanks jakob :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on September 19, 2004, 07:21:25 AM
near the q bias there is 1000/35v cap, marked as optional (*), is it really optional, and if so souhld it be bypassed?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 19, 2004, 07:35:09 AM
The "optional" 1000u cap close to the output stage is a good thing to have as it serves as local reservoir for the output stage. If you leave it out, at least mount a 100uF/35V here.

Jakob E.
Title: Toroid
Post by: keithcamilleri on September 19, 2004, 01:54:50 PM
Hi guys

I am not surer that I bought the right toroid will this work on the 1176  

25V-0-25V 160VA Toroidal Transformer

thanks ...
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on September 19, 2004, 03:04:45 PM
Quote
I am not surer that I bought the right toroid will this work on the 1176

25V-0-25V 160VA Toroidal Transformer


Yes it will work.

It is heavily overated for the job, but it will work.
Title: All things G1176 - the new "repost" thread.
Post by: Gustav on September 20, 2004, 08:35:46 AM
Not to rush it or anything, but I am making these boards 10 at a time right now, and I can see I will be out on the next shipment again. any updated on the revision ?

Gustav
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 20, 2004, 09:57:39 AM
Sorry, not finished yet...

I'm getting too many orders for Gyraf stuff right now - but it's on top of my to-do list...!

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Gustav on September 20, 2004, 02:59:12 PM
Quote from: "gyraf"

I'm getting too many orders for Gyraf stuff right now


Excellent !
Dont worrie about it. Most people should be able to handle a scalpel. Im gonna make a decent size batch this time.

Gustav
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on September 20, 2004, 05:26:51 PM
in the part list there is two 220p ceramic caps , and two 220p poliyesters caps, now in the layout (i saw a qustion in earlier post but without   exact answer) there are one 220p beneath ic2 (5532) and two 200p above q3, and the two 2m2 resistors.
one 220p i could not find at all (maybe a mistake?).
now wich should be ceramic and wich should be poliy, if it's matter at all?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 21, 2004, 04:19:39 AM
The two 200p's paralleling the 2M2 resistors R7 and R9 should be 220p polyester types. The others ceramics.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 21, 2004, 11:16:57 AM
My problem turned out to be a solder bridge and some traces that got lifted when I clumsily desoldered domething. I had the quick impression that one of the ratios was incorrect, but I have to check more carefully. Otherwise it seems to be working great. Thanks to Jakob, Bjorn Zetterlund and all who helped.

 :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 21, 2004, 01:14:19 PM
Good news, Seth!

 :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 21, 2004, 01:31:54 PM
Thanks, Jakob,

The compressor works great, it's just the meter calibration in GR that's wierd. The meter show 6dB of gain reduction at 1:20, but in the other ratio positions it shows greater reduction instead of less for the same input level. The output levels are correct on the meter and confirmed on my analyzer - as I add ten dB I get the correct amount of output for each ratio. I'm not sure that my generator is putting out 50mv in balanced mode when I'm calibrating. My meter is calibrated in dBm or dBv. Can someone tell me what 50mv is in dBm or dBv? Or, if I'm using a standard DMM am I looking for 50mv across pins 2-3 of the balanced input, or is it from pin 2 or pin 3 to ground? That's where I'm confused. I believe I've seen those calculations around here somewhere, so I'll go search.

Thanks.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 21, 2004, 01:40:56 PM
Seth,

The ratio problem you have has been discussed before here. I don't think it is a problem, but rather a misunderstanding of what the ratio switch does. They alter ratios, yes, but they also change the threshold - so there's no direct comparison between indicated GR and actual ratio. To find actual ratio, you'll have to input different levels, and monitor the output.

77mV is -20dB under 775mV, which is 1mW into 600 Ohms.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on September 21, 2004, 01:42:52 PM
Seth

I seem to remember that the threshold point changes depending on the ratio sttting you`re using, so I think what your talking about is normal.

Also most  DMM`s does not have a good frequency response & usually only go to about 400Hz with any degree of accuracy (even if they also function asa freq counter) so this may also be the cause of your problem.  For these types of measurments you`re better off with a scope or ant A.C millivolt meter.
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 21, 2004, 03:49:04 PM
Quote from: "gyraf"
Seth,

The ratio problem you have has been discussed before here. I don't think it is a problem, but rather a misunderstanding of what the ratio switch does. They alter ratios, yes, but they also change the threshold - so there's no direct comparison between indicated GR and actual ratio. To find actual ratio, you'll have to input different levels, and monitor the output.

77mV is -20dB under 775mV, which is 1mW into 600 Ohms.

Jakob E.


Thanks Jakob and Rob,

I understand. The output gain metering accurately reflected the selected ratios, but the change in threshold made the GR metering look wrong. So as you say, I misunderstood how the controls interact. That's good to know - I'm much easier to fix. Sounds like it's working fine. Thanks again for all your help. Pix to follow.
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 22, 2004, 12:57:24 AM
Here's some pictures - by happy accident I have a couple of extra channels for my Scully 280. They now have no knobs on them. I decided not to go nuts over the front panel, not now anyway - I'd rather build more stuff. It's definitely functional.

(http://sethglassman.com/Face.jpg)
(http://sethglassman.com/FaceL.jpg)
(http://sethglassman.com/FaceR.jpg)
(http://sethglassman.com/Inside.jpg)

 :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on September 22, 2004, 04:09:08 AM
I took a look at a real UA 1176 reissue today and noticed the input gain pot is a dual-pot, with two resistors soldered between the two pots and two sets of wires going to the PCB. The markings didn't tell me what ohms they were, but I am curious because here's what I found on comparing mine to the newer real one:

1. My input gain pot is way more sensitive (and touchy) in the lower range than the UA, making me think of trying out a linear pot instead of log.

2. Input thresholds seem lower on my G1176 version, but of course calibration comes into play.


thanks
-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: daArry on September 22, 2004, 04:12:34 AM
Can anyone who's ordered those sifam AL29's from within UK (farnell right?) gimme the part# for em - seems a few variations they have listed and there aint much to decipher between them...
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 22, 2004, 04:19:49 AM
Kdawg,

These are different versions of the 1176. Very different.

Daarry,

There's only one VU-meter AL-29.
Title: All things G1176 - the new "repost" thread.
Post by: daArry on September 22, 2004, 04:26:10 AM
Hey Jakob...

okay then so, from this list:

http://uk.farnell.com/jsp/endecaSearch/searchPage2.jsp?N=1003996+401&Ntk=gensearch_001&Ntt=sifam&Nty=1&specialorder=on&No=0&showImages=true&viewType=&comSearch=true&manufacturerDisplay=true

none of those are the correct vu type right?

this1 frm canford okay?: http://www.canford.co.uk/commerce/productdetails.aspx?productid=58-382

ta
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 22, 2004, 04:31:37 AM
Quote from: "daArry"
..okay then so, from this list:
http://uk.farnell.com/jsp/endecaSearch/searchPage2.jsp?N=1003996+401&Ntk=gensearch_001&Ntt=sifam&Nty=1&specialorder=on&No=0&showImages=true&viewType=&comSearch=true&manufacturerDisplay=true

none of those are the correct vu type right?


Right. They're useable for the SSL, not for 1176. We need a real VU-meter.

Quote
this1 frm canford okay?: http://www.canford.co.uk/commerce/productdetails.aspx?productid=58-382
ta


Yes, these are the right ones - they're even much cheaper than what I paid at Farnell...!

Jakob E.
Title: newbie questions
Post by: Brizco on September 22, 2004, 12:28:46 PM
hello

- can i use a 1,1K Ohm with 2W in the g1176?
- can i use 220p's instead of the 200p's which are marked on the pcb?


another questio g7 related:


ist it possible to do a chain of resistors : example: 3* 10M + 3* 1M: for a 33M ohm resistor?

thank you very much!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 22, 2004, 12:40:03 PM
Briz,

Yes, yes, and... Yes.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Brizco on September 22, 2004, 02:28:06 PM
i love it when you say yes!  :grin:

thank you very much!!!!!!!! :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 22, 2004, 02:43:29 PM
For the 33M in G7, just use 3x10M - that is enough..
Title: All things G1176 - the new "repost" thread.
Post by: daArry on September 22, 2004, 03:06:53 PM
great, cheers jakob - will get them later this week :) ordered the lundahls for the outputs from them on monday so cudda got them then...

cant remember when i started this 1176 project but i'm near there! Just got a panel design ready for schaeffer to do the biz too!:

http://notapplicable.co.uk/audiolab/1176/FrontDesign-[1176.jpg

peesh!

 :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on September 22, 2004, 04:44:29 PM
Quote
Just got a panel design ready for schaeffer to do the biz too!:


I don`t want to put a damper on your progress but I just tried to put 2 G1176 in one box with a similar layout to yours.  There are a couple of points that I recommend that you check before you place the order, so you don`t f**k it up like I did.

1.  Check where you have put the nuke switches.  I suspect that the bottom of the meter will be in the way.  This is because the meter covers below the level of its fascia behind the panel.

2. Check also that the Ratio & meter switch boards do not touch the nuke switch, the pots, & also the back of the meters.  What I found was that the switches project too far back to allow the switch boards to fit in place.  You may find that the 2 switch boards will give you more space for the nuke switch if you swap their postions.

I`m going to have to make a completely new front panel through my own stupidity.  I just don`t want you to spend a fortune with Schaefer & it doen`t fit.
Title: All things G1176 - the new "repost" thread.
Post by: daArry on September 22, 2004, 04:52:35 PM
good advice there rob  :thumb: I always print out a 1:1 template of any design and chek against the shiz just to be sure normally neways :) thanks!
Title: All things G1176 - the new "repost" thread.
Post by: al_p on September 22, 2004, 07:06:03 PM
yep. there's a lot of stuff that eats up panel space quickly if you are doing a dual. i'm using giant meters from an MCI tape machine. 3.5" wide, counting the mounting hardware, and just about 3.25" high with the illumination kit. also be aware of lips and flanges that connect your chassis to your panel. i haven't even started the guts yet, just doing metal work and mocking it up to make sure it's all good.
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 22, 2004, 10:13:17 PM
Quote from: "al_p"
yep. there's a lot of stuff that eats up panel space quickly if you are doing a dual. i'm using giant meters from an MCI tape machine. 3.5" wide, counting the mounting hardware, and just about 3.25" high with the illumination kit. also be aware of lips and flanges that connect your chassis to your panel. i haven't even started the guts yet, just doing metal work and mocking it up to make sure it's all good.


Also the chassis is sometimes not the full height of the face plate - in particular that's true of Par-Metal enclosures - so you can get a nasty surprise if you cut it too close. Par-Metal 1u enclosures are actually 1.32" high, or something like that. The covers also have flanges on the front edge, which you can cut away but it's a real pain. I built an SSL with a 1.5" meter and the box wouldn't close.  I had to buy another box and rip it all out of the Par-Metal box. You really have to read the specs - of course I saw later that it gave the actual height on the web site.

 :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: bluebird on September 23, 2004, 04:16:51 AM
I built two 1176's a while ago and have been using them for some stereo stuff.

I noticed the other day that when in "all buttons in" mode and letting some drums really breathe I noticed the release times of the two 1176's where significantly different.. With the drums panned center going through both units.

With both release knobs fully CCW I had to turn one almost to 12:00 for the "breathing" to match.

Although I haven't looked I'm assuming the release pots are the same. So I started thinking and remembered I had used two different brands of diodes (FD 333) in the sidechain circuits. A different brand in each 1176 that is.

would this cause the release times to differ?
Title: All things G1176 - the new "repost" thread.
Post by: Michael Krusch on September 23, 2004, 06:19:49 AM
I always print out my frontpanel design before I send it to Schaeffer and put everything on the paper to check it out. Has safed my much money.
Title: All things G1176 - the new "repost" thread.
Post by: bluebird on September 23, 2004, 11:09:41 PM
Bump

anyone have any ideas about my previous post?
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 23, 2004, 11:35:45 PM
Bluebird,

Did you match the Fets?


I used mine tonight for the first time, worked like a charm and sounded great. It's unbelievably rewarding. Thanks again Jakob and everyone who helped.

 :guinness:  :sam:
Title: All things G1176 - the new "repost" thread.
Post by: bluebird on September 24, 2004, 12:15:01 AM
No I did not match my fet's. so different fets will have different release times? gosh I would not think they would be so different.

interesting....
Title: All things G1176 - the new "repost" thread.
Post by: jrmintz on September 24, 2004, 12:26:32 AM
Quote from: "bluebird"
so different fets will have different release times?


I can't say that for sure, but if parts placement and values are the same in both units it's a place to start. Somewhere in this thread is PRR's fet matching jig. It's very simple and works great.

Good luck!
Title: All things G1176 - the new "repost" thread.
Post by: bluebird on September 24, 2004, 05:23:02 PM
Thanks jrmintz,

with a little searching I found PRR saying it would be very hard to have two 1176's tracking the same anyways....
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on September 28, 2004, 08:15:10 PM
Today my G76' made her debut at a real studio and it was a disappointment  :roll:  :cry:  The signal was very low.  It was barely there even with the in and out cranked all the way up.  It worked for me at home.  Could something have broke on the way there?  They were routing a vocal track from the SSL to it.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on September 29, 2004, 07:59:10 AM
[edit]
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 01, 2004, 12:16:22 PM
ok i pluged my unit and nothing burned (i hope), and the vu reacts to input signal, and in and out knob's.
i have built  mnat's version pcb and as i understand it ,because  the output tx is wierd 2:1 i shoul'd multiply by 2  the measures sujested by jacob in the output during the q bias calibrating , am i right?
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 02, 2004, 10:29:05 AM
ok after some more tests i discoverd that since i used 2n5457 wich have different leg order, i mounted them in the wrong way.
i turned them to the correct order.
now i have checked the transistors voltage, q2 to q9 seems fine, and the input and out put gain changes with the in/out pot's, and the voltage of the output seem's to be in order for 50mv input, about 6.9v
how ever q12 colector is pulsating so does q13 b&e q14 c b &e and q15 b&e, the output also start to pulsate(in fast attack time)
also the meter does not respond in gr mode (except for a slight movment when i turn tracking pot)

what coul'd be the cause of that?
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on October 04, 2004, 01:51:35 PM
Anyone have front panel artwork for a dual-channel 1176 in one case?  I'm still thinking about either having separate units or just putting two together, but the idea of having them in one rack unit appeals to me.  I checked the meta threads, but didn't find anything that specifically addressed this issue.

BTW, if any of you have made a combined unit, feel free to jump in with photos and any problems/remedies it required.

Thanks,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 06, 2004, 10:29:02 AM
ok i know i talk to myself here , but this is the conclusion

1. i'm a dumbass

2 i switched tl071 to tl072 by accident, that was the gr meter problem.

3. 2n5457 should be reversed to be pin compatible.

4. r66 was 82k instead of 182k that messed up the gr control amp,  q14 base was getting 14v instead of 3.5v but it was hard to measure because th dc pulsated.

i still didn't finish all the test but it's seem's  fine for now.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on October 06, 2004, 08:13:01 PM
Ok,  I have very little output volume.  Where do I start trouble shooting?  The Q's?
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 06, 2004, 08:36:08 PM
i would say take q1 out first, thats will take the fet and the side chain out of the equation.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on October 06, 2004, 09:41:40 PM
Even though I have little output wether in gain reduction, Vu or bypass mode?
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 07, 2004, 07:06:28 AM
yes, and i found in really helps to use sockets for q1 and q10 for quick troubleshooting (ok other people sujested that but i did not believed them :sad: )
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on October 07, 2004, 09:19:10 AM
I removed Q1 and the signal got much louder.  I replaced it with another one but the volume died down again.  Does this mean it's not the Q1 itself thats broken? What are the settings for testing voltages on the G1176?  Bypass mode with the release and attack full CW?  I'm having a devil of a time getting readings on my DMM's.
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 07, 2004, 04:24:28 PM
http://www.groupdiy.com/index.php?topic=646&postdays=0&postorder=asc&start=210
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 08, 2004, 03:49:22 AM
Orson,

You will have to do the trimming-procedure. This sets the FET to just knock-off 1dB. If adjustment to 1dB is not possible, you'll have to find another FET with different parameters.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on October 08, 2004, 12:14:16 PM
I remember reading this somewhere but I couldn't find the answer this time around. The voltage for the lamp on the schematic reads 35.4VDC (rectified, but unregulated). I'm ordering the Sifam AL-29WF and a light kit. Would you recommend the 24V or 12V light kit. Both will have to be trimmed down a bit but does either have an advantage? Will the 24V draw less current? Burn brighter? Thanks.
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on October 08, 2004, 06:47:40 PM
Quote from: "gyraf"
Orson,

You will have to do the trimming-procedure. This sets the FET to just knock-off 1dB. If adjustment to 1dB is not possible, you'll have to find another FET with different parameters.

Jakob E.


I understand.  Correct me if I am wrong here,  but what your saying is I can't tell if it's the BF245A thats broken unless I trim the new one to see if the lower output goes away?  Is there a way to find directly if the BF245A is fried?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 10, 2004, 04:22:41 AM
Quote
Will the 24V draw less current?


Yes. Use 24V lamp and an appropiate series resistor.

Quote
I can't tell if it's the BF245A thats broken unless I trim the new one to see if the lower output goes away?


Exactly.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: daArry on October 10, 2004, 04:32:56 AM
Hey, I just more or less finished stuffing my 2 1176 pcbs - just waiting on canford to send me some damn output iron...anyway, thought I'd test to see if sound would go in and out - and it does but it sounds very low, and if it goes over a certain input level (still low by any standards) some big clipping/distortion starts...does this sounds right considering no audio tx's been stuffed yet? Also, i've no meter wired in yet...I guess I should be checking voltages compared with the schem right? Having the output tx there or not shudnt effect what spot sees what V right...
Title: All things G1176 - the new "repost" thread.
Post by: kvintus on October 15, 2004, 06:02:53 AM
Hi all!

Some of you may remember that I tried building an 1176 last year. However, I couldn't get rid of the hum so I put the thing on the shelf. After reading about the famous PCB ground loop cut, I decided to give it another chance last night.

Success!

No hum. But the noise level is quite high, about -91 dBu. Is this normal? What's the noise floor level for the original 1176? What about your clones?

/Anders
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on October 16, 2004, 12:56:46 PM
Quote from: "gyraf"
Orson,

You will have to do the trimming-procedure. This sets the FET to just knock-off 1dB. If adjustment to 1dB is not possible, you'll have to find another FET with different parameters.

Jakob E.


I performed the trimm- procedure for the new BF245A(Q1) and the result was a small improvement in overall output volume but was not as good as it was before.  I used to have lots of head room with the output set at  1 o'clock.  Now I have to go to three or four o'clock for the same level.  I have now tried 4 different BF245A's with the same result.  I made sure all things were equal (settings on mic pre, g1176 and input to sound card).  So using the same values for each parameter the over all volume is still lower than it was previously.

  I remember people mentioning how different BF245A's can effect the compressors performance.  Perhaps I need to try more of them?   Would matching the new one to the other I have in there help?  I am still unsure if the problem is the BF245A at this moment.
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on October 17, 2004, 05:47:45 PM
did you tried measure the voltage on the fet gate, as in the message i linked before?
Title: All things G1176 - the new "repost" thread.
Post by: deanp920 on October 17, 2004, 11:29:32 PM
Orson,
Quote
I performed the trimm- procedure for the new BF245A(Q1) and the result was a small improvement in overall output volume but was not as good as it was before. I used to have lots of head room with the output set at 1 o'clock. Now I have to go to three or four o'clock for the same level. I have now tried 4 different BF245A's with the same result. I made sure all things were equal (settings on mic pre, g1176 and input to sound card). So using the same values for each parameter the over all volume is still lower than it was previously.

I remember people mentioning how different BF245A's can effect the compressors performance. Perhaps I need to try more of them? Would matching the new one to the other I have in there help? I am still unsure if the problem is the BF245A at this moment.
Go through your G1176 stage by stage without Q1 in the circuit, making sure that your AC gain structure is correct per our previous troubleshooting sessions in this thread. Also make sure that your Qbias voltage is still around -2Vdc. You can check this off the release pot as we have discussed before.

kvintus,
Quote
No hum. But the noise level is quite high, about -91 dBu. Is this normal? What's the noise floor level for the original 1176? What about your clones?
Quite a bit of hiss seems normal on these units. Nowhere near as quiet as modern line level gear. Still works fine, though.

Dean
Title: Another DIY convert is born!
Post by: MrShhh on October 26, 2004, 08:41:40 AM
Hello everyone,

I've just finished my second project to date, one of Gyraf's 1176 clones and it's been quite a learning curve so far! The amount of effort gone into the project and associated forums is a credit to everyone involved. Great stuff!

The good news is it passes a signal and even sounds lovely and warm. The gain reduction meter and VU both work. However, I've got a problem with low gain that you might be able to help with. Here are some test figures and conditions I've carried out:

Conditions:

200Hz 50mV rms sine wave signal at input.
Input and output pots set to max
Attack and release set to max
Ratio set to 1:4
Meter on bypass
Optional input traffo installed
No traffo mods for higher gain

Measurements with Q1 in place:

Input wiper to gound:           33mV
Output wiper to ground:        19mV
Across 2&3 of output XLR:     33mV  (unit is balanced so pin 1 already grounded)
Ground to traffo side of C15:  ?   (can't locate C15 from the componant layout)

Q bias trimmer fully CCW, ratio 1:20 and release fully CW:

Ground to pin 1 of release pot:    -0.268 V DC
Ground to pin 2 of release pot:    -0.627 V DC
Ground to pin 3 of release pot:    -0.627 V DC

With Q bias trimmer fully CW, above 3 readings are all 0V DC

Measurements with Q1 pulled:

Input wiper to gound:           cycles between 6.53 and 6.56V
Output wiper to ground:        cycles between 6.59V and 6.72V
Across 2&3 of output XLR:     1.28V
Ground to traffo side of C15: ?  

Q bias trimmer fully CCW, ratio 1:20 and release fully CW:

Ground to pin 1,2 & 3 of release pot: All readings cycle periodically between -4 mV and +4mV DC    

Here are my Q readings:

E B C
Q2  0.5     1.02  1.75
Q3  1.13   1.75  11.86
Q4  11.25 11.86 29.5
Q5  4.31   4.77  27.8
Q6  28.3   27.8  14.1
Q7  29.0   28.3  14.1
Q8  13.5   14.12 29.5
Q9  13.44 12.82 0.0012
Q12 3.92  4.47   14.84
Q13 14.2  14.8   29.5
Q14 2.86  3.43   16.8
Q15 16.3  15.3   29.5

There seems to be several issues here:

With Q1 in place:

1. Output voltage is really low (19mV across 2&3 of the ouput XLR is way too low, should be above 6V)
2. Input and output wiper voltages are too low at 33mV and 19mV (should be around 50mV and 0.96V, althought the 33mV could be that I'm losing 17mV in the input traffo)
3. Q bias voltage should be better than -2V DC with the trimmer fully CCW (-0.627V is no where near)

With Q1 pulled:

4. There is a strange cycling of readings at the input and output wipers and the Q bias voltage
5. Input & output wiper voltages are far too high at 6.53V and 6.59V (should be more like 50mV and 1V)
6. Voltage across 2&3 of output XLR is far too low at 1.28V (should be above 6V)
7. Q bias voltage should not change much when Q1 is removed

The state of play is, I've identified a number of problems but need some help as to how I can go about fixing them, most of all where to start looking for what might be causing them.

Many thanks in advance!  :grin:  :green:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 26, 2004, 08:49:42 AM
Maybe a bad Q1 FET? Have you tried a different one? Is it the right type?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: MrShhh on October 26, 2004, 09:03:14 AM
Thanks Jacob, I'm just about to try another Q1, I've got 1 left! The ones I'm using are BF245A from Farnell.

I'll post an update with the results.
Title: All things G1176 - the new "repost" thread.
Post by: MrShhh on October 26, 2004, 09:51:33 AM
Just tried a new BF245A but all the readings are still the same.

I also soldered a 3 pin socket onto the PCB so this time the BF245A wasn't heated at all.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 26, 2004, 10:02:56 AM
Have you tried with the Q-bias trimmer turned the other way around? Does that do any difference?
Title: All things G1176 - the new "repost" thread.
Post by: MrShhh on October 26, 2004, 10:07:58 AM
The Q bias trimmer doesn't significantly change any of the readings.

Turning it fully CW instead of CCW decreases the voltage between 2&3 of the output XLR by 4mV and between ground and the output wiper by 3mV.
Title: Panic over!
Post by: MrShhh on October 29, 2004, 05:29:39 AM
Hi there,

I now have an 1176 in perfect working order with zero hum and very low hiss!!!!

In the end I decided I wasn't happy with the PCB so I made a new one and stuffed it from scratch. Where I'd been swapping components in and out, the old one had become quite a mess.

I bought a diode/transistor tester made by a company called Atlas and tested all the old components. I couldn't recommend the tester more highly. It quickly showed that BD135 & BD136 were fried, hence no gain at all. A couple of BC107B's were also partially fried.

Other than that, I've discovered that it's vitally important to use decent shielded cable between the input and ouput XLR's. Before I had unshielded cable thinking I'd get away with it but the interference was so bad I could even hear my cordless mouse chattering digital rubbish at me! Hard to pin down as it sounded exactly like an earth loop.

A million thanks to everyone for making this website so informative! I've had a lot of fun making the 1176. Next on my list is an LA2 tube compressor and then of course there's the Pultec EQ....................
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on October 31, 2004, 07:07:09 PM
Well, I finished up my first 1176 using Gustav's boards with the "Hitchhiker" cut and the perimeter ground buss wire mods.  It's quiet and passes signal, but I'm not sure it's working correctly.  I've been trying to calibrate it and wonder if I'm doing something wrong as I can't seem to get the GR Meter Tracking Adjustment to happen.

Here's what I've done so far:

Q-Bias Adjustment

I used the following instructions (don't know who wrote it, but I think it was Dean):

The proper adjustment of this trimmer is made like this:  

Input a weak signal, around -10dB or something and measure the AC output level without gain reduction.  I did this using a 250Hz signal at .3 volts.

Set the attack and release controls fully clockwise, the ration to 1:4, and the output level to max.  Turn the input level so you get something readable, like 100mV on your voltmeter on your output. I did this exactly as written.

Now adjust the Q-Bias trimmer until you have a 1dB drop in output level.  That's it.   I adjusted the trimmer until the output voltage stabilized at 89mV.  Is this right?  Also, is the Q-Bias adjustment kind of finicky?  When I start with it fully CCW, I have to turn it fully CW and then after a bit the level starts to drop.  I then move it back towards the middle of its range and can dial in the correct final drop then.  What do you think?

GR Meter Tracking Adjustment

Set ratio to 1:20, set meter to bypass.  Input a 1kHz, 50mV signal.  Set input level to ~12 o'clock.  Set output level so you get 50mV at the ouput also (now you have unity gain).  Now set the meter switch to "GR."  Slowly turn up the level of your input signal (at the signal source, not with the input level control) while you monitor both input and output levels with a voltmeter.  

Now here's where it gets weird for me:
When you reach a point where the output level is half the input level, you have a 6dB of gain reduction in the unit.  How many volts are we talking about here?  My output voltage doesn't really start lagging until I get a pretty hot signal in the input.  Where should the input and output voltages be when they reach this 2:1 ratio? BTW, I'm using the stock wiring setup on the output tranny.

Power Supply Voltages:

Primary: 118 VAC
PCB: 30.5 VDC and -9.8 VDC

Here are the voltages I measured for each transistor:

          E          B          C
Q2--.51--1.03--1.83
Q3--1.20--1.83--11.85
Q4--11.36--11.96--30.5
Q5--4.41--4.87--28.7
Q6--29.3--28.7--14.47
Q7--30--29.3--14.47
Q8--13.84--14.47--30.5
Q9--13.80--13.19--0.0
Q12--2.38--2.88--9.75
Q13--9.17--9.76--30.5
Q14--1.62--2.17--10.69
Q15--10.15--10.69--30.5

Any help would be greatly appreciated.

Cheers,
 :guinness:  :sam:  :guinness:  :sam:
Don
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 01, 2004, 03:22:02 AM
Don,

If you have compression, but GR meter tracking problems, try with a different GR meter FET. At best one that is matched with the VCA-fet.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 01, 2004, 11:26:38 AM
I've tried four different FETs in that position and they all track the same.  I ordered some more and the correct resistors to make PRR's matching circuit, but it seems that the problem is elsewhere.

Any thoughts on where the voltages should be for the input/output ratio?

Also, does it sound as though my Q-bias adjustment is working as it should?

Thanks,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 01, 2004, 11:30:11 AM
The absolute input/output volts you adjust your meter at dosen't matter. If 1V input is needed to make the output go to 0.5V, that is still -6dB.

Have you verified that you have compression working?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 01, 2004, 06:18:46 PM
Quote from: "gyraf"
The absolute input/output volts you adjust your meter at dosen't matter. If 1V input is needed to make the output go to 0.5V, that is still -6dB.


I have to get it up to 5 or 6 volts on the input before I see even a 25% difference between input and output voltage.  This seems wrong, though it could just be me.

Quote
Have you verified that you have compression working?


The unit doesn't seem to be compressing at all.  I just spent some time with it in the studio and it passes audio fine.  It's very clean (no hum or hiss)  and the VU meter tracks in VU mode but when I switch to GR mode, the meter just hangs on zero.  

Heres's something Dean wrote:

Quote
Ok, I get about -1.8V at the gate of Q1 with my bias set for 1db cutoff. I can adjust this from -2.3V to 0V with the Qbias trimmer.


I get this range of adjustment with my Qbias trimmer.  

Then he wrote:
Quote
Use a 50mV, 250Hz input signal. Measure with your DMM for now and hold off on the scope(perhaps use it to look for clipping only right now). This way we can compare AC readings in RMS.

With this input signal, put the input and output at max(full CW). Ratio = 20:1. Attack and release don't matter, just set them like the manual says. Unit in bypass. Measure across input XLR pins 2 and 1&3. You should have ~50mV.

Measure from the input potentiometer wiper to ground. You should have ~50mV(a little less if you have the transformer input...I'm losing about 15mV, or 3db through the input transformer). So, 50mV at the input wiper with the IC input, or 35mV at the input wiper with the transformer input.

At this point, I would hop over to output XLR pins 2&3 and measure across them with the DMM. Turn the Qbias pot full one way or the other until you have max signal. You should have about 4.8V with no clipping(~6.8 with the IC input). Back off the Qbias trimmer until you have about 4.3V(~6V with the IC input) and that should set the Qbias fairly close. You just want Q1 to start cutting off a little bit, that's all we're doing here.


I only get about 1.5V on my output max.  My output tranny is wired in the stock configuration for Gustav's board; that is, it's 2:1 input to output, respectively.  

I've also tested the FETs I have using PRR's circuit and used ones that measured 6.57V and 6.63V.  

I'm going to go and try to see if it works in the studio again, but is there anything here that appears to be off?  I've traced down my -10VDC supply and everything appears OK, and the range I get on the gate of Q1 seems to bear this out.

Thanks again for your help and all the work you've put into this project from its inception.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 04, 2004, 02:44:40 PM
Well, I've checked all the resistor values, traced the circuits, examined the traces to make sure there are no shorts/opens, but I still can't get this thing to compress.  Here are the voltages that seem off (curiously enough, they are all in the GR circuit):

Q12--2.38--2.88--9.75
Q13--9.17--9.76--30.5
Q14--1.62--2.17--10.69
Q15--10.15--10.69--30.5

Also, when using PRR's testing setup for the FETs, should they fall in any kind of voltage range or are they usually kind of all over the map?  

I received a bunch of extra transistors from Mouser today and I plan to tackle this thing again tonight.  My feeling is that there are some marginal ones in the GR circuit.

Any ideas would be greatly appreciated.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: rafafredd on November 05, 2004, 12:36:15 PM
I´m running away from FAIRCHILD SEMI after I´ve seen several people talk about how crappy it is.

But I´ve finally got some BF245a for my 1176 clones, and unfortunetly I think those are Fairchild. OUGH!

Take a look:

(http://hps.infolink.com.br/rafafredd/BF245a.gif)

Does it looks like it´s a Fairchild FET?

Anyone used one like this in the 1176? What was the results?

thanks!
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 05, 2004, 05:41:52 PM
Quote from: "rafafredd"
I´m running away from FAIRCHILD SEMI after I´ve seen several people talk about how crappy it is.

But I´ve finally got some BF245a for my 1176 clones, and unfortunetly I think those are Fairchild. OUGH!

Take a look:

(http://hps.infolink.com.br/rafafredd/BF245a.gif)

Does it looks like it´s a Fairchild FET?


Yes.

Quote
Anyone used one like this in the 1176? What was the results?


I matched a couple using PRR's setup and then used them in mine.  They seem to work fine now that I found the problem in my unit, which was a bad Lorlin switch.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: rafafredd on November 06, 2004, 05:44:13 AM
So, I´ll go FAIRCHILD in my 1176s...  :cool:
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 06, 2004, 08:12:17 PM
Quote from: "rafafredd"
So, I´ll go FAIRCHILD in my 1176s...  :cool:


Just use sockets so you can change them easily if you ever desire.  I socketed Q1 and Q10 in my 1176s.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: rafafredd on November 06, 2004, 08:17:46 PM
I´ll do it. Thanks!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 07, 2004, 05:37:06 AM
Quote from: "idylldon"
..seem to work fine now that I found the problem in my unit, which was a bad Lorlin switch.


Great!

I'm glad you got that sorted out..!

 :thumb:

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on November 07, 2004, 01:04:12 PM
I started tracing parts for my next project (the 1176 clone) and I'm having trouble finding the 6u8/35v electrolytic cap (RS, Farnell, conrad in the Netherlands don't have this cap)
All I can find is a solid aluminium 6u8 cap but this is only 30v.

Is it ok if I use a tantalum 6u8/30v cap instead, or should I go for the solid aluminium one?
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 07, 2004, 01:47:26 PM
Quote from: "radiance"
I started tracing parts for my next project (the 1176 clone) and I'm having trouble finding the 6u8/35v electrolytic cap (RS, Farnell, conrad in the Netherlands don't have this cap)
All I can find is a solid aluminium 6u8 cap but this is only 30v.

Is it ok if I use a tantalum 6u8/30v cap instead, or should I go for the solid aluminium one?


Are 10u/35 electrolytics readily available?  If so, they'll work just fine.

Cheers,
--
Don
Title: Re: Panic over!
Post by: robomatique on November 08, 2004, 03:34:21 AM
Quote from: "MrShhh"

I bought a diode/transistor tester made by a company called Atlas and tested all the old components. I couldn't recommend the tester more highly. It quickly showed that BD135 & BD136 were fried, hence no gain at all. A couple of BC107B's were also partially fried.


Sounds like a nice thing to have around, anyone know where I can get one?

Robert
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 08, 2004, 03:36:54 AM
There's no problem in using 10uF electrolytics in stead of the 6.8uF's. Voltage rating should be 35V or higher.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on November 08, 2004, 07:43:37 AM
Thanks idyllion & Jakob.
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on November 08, 2004, 04:40:40 PM
Someone was working on a Mouser project for the 1176. It was a link that had most of the parts already listed for you to order. I saw it once and now I can't find it. Does anyone have that info, and if so can we add it to the G1176 meta? Thanks.
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 09, 2004, 03:15:12 AM
Third post down in this thread, though this might not be what you're looking for because it's in the meta.

http://www.groupdiy.com/index.php?topic=372

Cheers,
--
Don
Title: Pots
Post by: keithcamilleri on November 09, 2004, 01:13:41 PM
hi guys,

I'm about to wrap up the G1176 project but i'm a bit confused about the pots... I don't know which are log and which are lin, I'm a bit mixed up...could someone please help me out?


thanks  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: daArry on November 09, 2004, 01:18:58 PM
4M7 Lin POT 6mm RELEASE
22K Lin POT 6mm ATTACK
100K Log POT 6mm OUTPUT GAIN
10K Log POT 6mm INPUT GAIN

happy wrapping  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on November 10, 2004, 02:39:30 AM
:green:  :thumb:  :thumb:  

cheers daARRy
Title: Semiconductor tester
Post by: MrShhh on November 10, 2004, 02:00:03 PM
robomatique,

Sorry for the long wait, a virus took out my internet connection for the last week!

The tester is called "peak atlas DCA" and can be bought from Maplin for £49.99:

http://www.maplin.co.uk/Module.aspx?ModuleNo=31538&TabID=1&source=15&WorldID=&doy=10m11

Easier than a multimeter for testing transistors/diodes as you don't need to know which leg is which, the tester works it out for you.

 :green:
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 10, 2004, 02:19:27 PM
I tested and calibrated my G 1176LN last night on my bench and it's passing signal, compressing, and everything seems to be working. I don't know of a way to test attack and release, so I'll have to give that a listen when I get some audio through it. I'm taking it to UNO (where I go to school) and will use their distortion analyzer and get that trimmed up. I'm very, very excited and should have it to my studio tonight or tomorrow and have a listen.

Thanks Gyraf (for the project) and nrgrecording (for some panel graphics).

I'll post some pics and some specific details in a few days when I'm confident all is working as it should.
Title: All things G1176 - the new "repost" thread.
Post by: xsmsx on November 11, 2004, 07:31:11 AM
Hi there,

what's wrong when I get -7 insted of -10 Volts near the 5532. It's a really strange thing. When I touch the trace with my multimeter I sometimes get -10 Volts and the GR-Meter shows 0dB. I already looked for breaks and soldering faults but I coudn't find the reason. By the way, I get these problems on each of my 3 Units! Does anybody know what to do???

Christoph
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 11, 2004, 07:41:45 AM
Quote
I sometimes get -10 Volts and the GR-Meter shows 0dB


does the GR meter ONLY act correct when you measure -10V, or does it work always?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: xsmsx on November 11, 2004, 08:03:00 AM
It only works right when I measure -10 Volts.
Christoph
Title: Re: Semiconductor tester
Post by: robomatique on November 11, 2004, 09:00:31 AM
Quote from: "MrShhh"
robomatique,

Sorry for the long wait, a virus took out my internet connection for the last week!

The tester is called "peak atlas DCA" and can be bought from Maplin for £49.99:

http://www.maplin.co.uk/Module.aspx?ModuleNo=31538&TabID=1&source=15&WorldID=&doy=10m11

Easier than a multimeter for testing transistors/diodes as you don't need to know which leg is which, the tester works it out for you.

 :green:


Thanks!!!

Looks really nice! But as I understand it I could use a multimeter for this purpose? I don't have a multimeter for the moment (using one from work) and I am thinking of buying one. For the moment I am only using them for measuring resistance and check for shortcuts, but would a £25 multimeter be ok for measuring transistor hfe?

Because I need my own multimeter, £25 for a multimeter would seem more useful than £50 for the tester? Anybody?

Robert
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 11, 2004, 10:59:07 AM
I finished calibrating my G 1176 yesterday afternoon. I then began to just sweep through some frequencies and get a feel for how this comp operates since I've actually never used one before.

One thing I noticed is that at lower ratios (ie 4:1 and 8:1) with 3 to 6 dB or so of compression, I couldn't always get the output back to 0VU (+4dB). At 12:1 and 20:1, I didn't have any trouble getting back to 0VU. I've heard mention and read about the mods that can be done for more gain. But I just want to make sure that the operation I'm seeing is typical of Gyraf's unmodded board/output trafo. I just want to rule out this it's not something else behaving improperly. Also, the signal looks great on a scope. Can I get some insight or thoughts on this?

I will be getting it into my studio this afternoon, so I'll be able to hear it and see how it operates in my setup... can't wait.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 11, 2004, 11:28:39 AM
Christoph,

Check for cold solderings..
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 12, 2004, 01:19:45 PM
I got my G1176 into my studio yesterday, and I must that this compressor/limiter sounds excellent (as many of you already know). I also did some tracking last night and used it on a bass track... it held things together well and I had it working rather heavily and I wasn't hearing any kind of pumping or artifacts. And the attack times are obviously extremely fast. And it doesn't sound like any other comps I have.

But I did have a little bit of hum coming from the unit. With relation to the signal, it is very small, but there was definitely some bzzzzzz introduced from the unit that was audible when no signal was present. I'm going to try and use an extra ground strap to see if that helps. Also, with the output all the way up I was only reaching -5dB on the VU. I'm thinking I should probably try one of the gain mods.

Any comments or suggestions?!?
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 12, 2004, 01:38:22 PM
Quote from: "Greg"
But I did have a little bit of hum coming from the unit. With relation to the signal, it is very small, but there was definitely some bzzzzzz introduced from the unit that was audible when no signal was present. I'm going to try and use an extra ground strap to see if that helps. Also, with the output all the way up I was only reaching -5dB on the VU. I'm thinking I should probably try one of the gain mods.

Any comments or suggestions?!?


As to the hum problem, did you reinforce the ground plane around the board via adding a buss wire and also do the "hitchhiker" cut mod to the traces?  Of course, if you have mnat's board then I don't think this applies.

I did both of these and pulled a ground wire from the board and attached it to the center of the back panel via a #10 bolt/nut.  I also attached the AC ground point here.  The ONLY ground I have from the board to the case is this one.  Even with the output trannie mod that reflects the original design (1:2), I have zero hum unless the gain on my board and power amp is insanely high (read: higher than I'd ever use it), and even then it's barely audible.

As for the output level, I like what the 1:2 mod does for the output.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: MrShhh on November 12, 2004, 06:18:13 PM
Quote from: "Greg"


Any comments or suggestions?!? (Re: hum)


I spent a lot of time trying to rid the unit of hum and what sounded like ground loop noise. I re-routing all the ground points, did the hitchhiker cut and soldered on the extra ground strap only to find that the problem was the cheap & nasty unshielded input cable I'd used to connect the input XLR to the PCB. As soon as I used good quality cable with a braided shield, the hum and noise reduced to almost inaudible, even at very high gain settings. I also kept this cable length as short as possible to try and minimise any interferance it might pick up.
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 12, 2004, 11:37:17 PM
That's one data point I forgot to add; that is, I used shielded cable as well on the input.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on November 13, 2004, 06:25:59 AM
Quote
I did both of these and pulled a ground wire from the board and attached it to the center of the back panel via a #10 bolt/nut. I also attached the AC ground point here.


The point that you make you`re star ground connection to the chassis should ideally be as close to the input socket/s as possible for least hum.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 13, 2004, 09:43:02 PM
Thanks for tips guys. I'll do all of the above and check back... I'm using unshielded I/O cables. I have some Mogami shielded cable lying around that I'll use for the I/O. I already did the hitchiker cut and I'll add the grounding buss wire. I'm sure this will rid my unit of hum as well.

But I must say, the more I use this compressor, the more I love it... I used it on a session today and it's a great tool to have.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 15, 2004, 12:23:02 AM
Just an update... prior to the additions suggested, I was reading about 50-75mV peak "hum" on my scope when the input and output were cranked up with no input signal. After these tweaks, I'm now reading < 5mV peak. In fact, when I simply remove the connection to the chassis, it shoots up to about 50mV peak. Once I reconnect, it drop to < 5mV peak. I haven't tried this unit in my studio, but I'm fairly confident I won't be having any hum issues. What do you guys think?
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on November 15, 2004, 02:44:23 AM
It is normal to measure hum with the input grounded.  If you have both gain controls fully up with the input floating you will be more likely to pick up interferance.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 16, 2004, 11:04:04 PM
Hum is gone... thanks everyone.

Now for the final thing, the output tranny gain mod.

I've got the pin assignment:
 2&4 - Input (negative side of C15)
 5 and 1 to 3 - Ground
 6&9
 10 - (+) Output
 7 - (-) Output

Now do I just just take 10 (+) and 7 (-) back to the board where the original trafo was connect, which is point Y and X, respectively?
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 17, 2004, 04:22:16 AM
I used Dean's instructions as follows:

If you want to try it 1:2, in and out connections should be reversed - by cutting tracks and soldering on some wires. On the primary, pin 4 should be isolated from the ground plane by cutting the wide ground trace with a dremel tool or utility knife.

The trace connecting C15 to pin 1 must be cut.

On the secondary, pins 6 and 9 need to be isolated by cutting the traces near the pins.

Solder a jumper wire from pin 4 to the solder pad for point Y.

Solder a jumper wire from pin 1 to the solder pad for point X.

Solder a jumper wire from pin 9 to the solder pad for the negative side (output) of C15.

Solder a jumper wire from pin 6 to pin 3.

That should leave the transformer running 1:2, and increase in the signal line amp's gain by 12db.

For what its' worth, I measured the transformer's output impedance, wired stock (2:1), at about 30 ohms. This is encouraging, since, when wired 1:2, the output impedance should still be well under 600 ohms.


This worked out very well for me.  I finished my second 1176 and both of them are working flawlessly.  I truly don't know how I ever got along without them.  I'm thinking of building another pair in one box and having the option to link them.

Thanks again to all who have contributed so freely with their knowledge to this great project.  I couldn't have owned one of these without being able to do it myself because a *real* one is out of my budget range right now, and most likely will be for quite some time.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 17, 2004, 11:05:44 AM
I went ahead and wired mine up last night with the "Chef" mod, which actually puts the tranny in a 1:1 configration (it doesn't swap the primary and secondary, but rewires them), which gives about +6dB more gain...  :grin:  I decided to mount and connect the tranny on perf board so I could avoid cutting traces and this would allow me to go back to the 2:1 is necessary. But this mod puts it in 1:2, which gives +12dB more gain than the original  :grin: :grin:  ...

Hope I'm not beating this topic to death, but would either of these mods have an advantage regarding output impedence?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 17, 2004, 11:10:55 AM
Quote
would either of these mods have an advantage regarding output impedence?


Not really. The output stage has VERY low output impedance, and will happily drive just about anything on the output side.

But you may need to take care if you used the BC327/337 as output transistors - these will probably not survive shorting the output at full level with 1:2 transformer.

Jakob E.
Title: 1176
Post by: keithcamilleri on November 21, 2004, 08:48:16 AM
Hi Guys,

finished a G1176, output and input gain working fine...I'm going to test the unti for the right voltages... my problem is that it is not compressing...

any thought from where I can begin to check the unit?

Thanks

by the way It has a small bzzzz to it but I havent earthed anything still...
Title: Re: 1176
Post by: idylldon on November 21, 2004, 11:50:23 AM
Quote from: "keithcamilleri"
. my problem is that it is not compressing...

any thought from where I can begin to check the unit?


Double check all the solder joints and wiring.  The first one I built didn't compress and it drove me crazy trying to track down the problem.  It turned out to be a bad Lorlin switch.  After changing it, the unit worked flawlessly.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on November 21, 2004, 02:29:45 PM
thanks idylldon..

for your reply....

Maybe this narrows it down... at point 7 the voltage are not changing , I cheked point 21 and voltages there goi between -5 -2 approx..so there it's looking that is working fine...

the gr tracking setting is not done since the unit is not doing gain reduction all other setting are done...

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on November 22, 2004, 07:45:43 PM
I'm curious as to what fuse values everyone is using.  It seems as though the UREI schematic says 1/4 amp for 125V (though the schematic is hard to read and it doesn't specify fast or slow blow), the Purple Audio schematic says 1/8 amp--slow blow, and the North American Parts List gives a Mouser number that is a .375 amp fuse.  

Is there a consensus on the rating?  Fast?  Slow?

Thanks,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 23, 2004, 03:54:40 AM
Keith,

First of all - does point21 change with signal level?

There is a "threshold" - the negative voltage at point21 - that has to be overcome by input signal level before the FD333 diodes starts to conduct.

Input a loud signal, input at max, and measure changing DC voltage at point21. When this voltage is some +0.6V higher than the DC voltage at point19 (which is set by Q-bias), the diodes conduct, and gain-reduction sets in. Start out with trying different settings for your Q-bias, just in case it is at one extreme.

Does meter and gain change with Q-bias adjustment? This verifies that the FET's and the release circuit is working.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on November 23, 2004, 07:22:19 AM
hi jakob,

i'll check if point 21 changes with signal...it sure does change without signal...


Quote

Input a loud signal, input at max, and measure changing DC voltage at point21. When this voltage is some +0.6V higher than the DC voltage at point19 (which is set by Q-bias), the diodes conduct, and gain-reduction sets in. Start out with trying different settings for your Q-bias, just in case it is at one extreme.

I will try this tonight

as regarding if the meter and sound level changes qith q bias trimmer yes it does change...
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 23, 2004, 07:35:04 AM
Quote
as regarding if the meter and sound level changes qith q bias trimmer yes it does change...


Which means that the FET attenuator part is OK, but just not receiving any control-voltage from the rectifier circuit..

If voltage changes correctly with signal level minus threshold at the output of the two diodes, then check that your attack pot is correctly mounted and working. This is the only component between rectifiers and the FET gates.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on November 24, 2004, 05:10:20 AM
Hi Jakob,

had a bc107 soldered badly...now the unit is compressing but I can't calibrate it since I don't have enough tools... and my DMM died on me yest... aaaagggrrrhhhh...

I'm not convinced that it's working well I'll post some voltages here later today...
Title: All things G1176 - the new "repost" thread.
Post by: radiance on November 24, 2004, 02:13:51 PM
Today I did the Fet matching thing using PRR's setup.
After putting the transistors in the wrong way for some time (I hope it did not fry them) I got the hang of it. I got values between 4.71v DC and 7.42v DC (matching the BF245A FET Transistor).

Q) How well should I match  for building a stereo 1176. Is for example 6,51v DC and 6,40v DC close enough or is this way overdone?

Also, what about the other transistors like the BD517 ,BD518 and the BC560 , BC107, should I match them as well? And if so, can I use PRR's setup for this?

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 25, 2004, 04:23:51 AM
Rad,

Quote
Q) How well should I match for building a stereo 1176. Is for example 6,51v DC and 6,40v DC close enough or is this way overdone?


The "real" 1176's are known to not track well. I'd say 6,51V and 6,40V is close enough - after all the last bit of trimming is what the 1176SA stereo-adapter is for..


Quote
Also, what about the other transistors like the BD517 ,BD518 and the BC560 , BC107, should I match them as well? And if so, can I use PRR's setup for this?


No. These are non-critical.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on November 25, 2004, 07:01:40 AM
Thanks Jakob!
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on November 29, 2004, 05:33:26 PM
Hi guys,

finished up two 1176s ..just calibration needed. Made the romejesus cut to the board and done ground reinforcement (the hum is very very very low) but there is a hiss not loud but it's there... just wanted to ask whether anyone got rid of this hiss...

units still not grounded yet to the cases (no star ground , and no shieled ins and outs....)

thanks
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 30, 2004, 08:58:31 AM
Some hiss is a part of any FET compressor..
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on November 30, 2004, 10:55:05 AM
cheers jakob  :green:  :green:

gonna do the calibration I'll post pics later...

thanks dean, jakob and orson and everybody learned loads by reading your posts  :thumb:  :thumb:  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: daArry on December 02, 2004, 06:12:09 AM
Hey

Right, got me boxed near done! time to calibrate...which i've never done before - not with any audio hardware...

So, from readin the gyraf site I rek I can handle tests 1, 2 and 3...but 4 is where the headache starts...How/where do i get a 50mV signal from? IS this what those scope things do i take it ye? I have a PC and a multimeter - can i do nefin with these? I can send out tones n sh*t at specific levels n meter on the box too...

Do i really need to do this? the damn thing sounds great as is! :green:

- I would like to understand a lil more tho   :thumb:

Cheers

D
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on December 05, 2004, 01:42:51 PM
hi guys,

I'm in the process of calibrating, but or I am doing something wrong or the 1176s (both of them) are not working as they should.  :sad:

Q BIAS SETUP

I am putting a 1khz .775mv , I'm adjusting the output and input to get a voltage reading 0.875 for +1db used the formula db = 20(log[v1/v2]). (Hope I used it right I'm not great in maths :roll: )  IS THIS RIGHT?

This sets up the gate of q1 around  -.9 mv.

GR Tracking

I can't get unity gain here it's seems that there isn't enough gain to get the 50mv that I'm putting through.

Am I doing anything wrong in the q bias setting?

cheers
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on December 05, 2004, 01:56:07 PM
Quote from: "keithcamilleri"
hi guys,

I'm in the process of calibrating, but or I am doing something wrong or the 1176s (both of them) are not working as they should.  :sad:

Q BIAS SETUP

I am putting a 1khz .775mv , I'm adjusting the output and input to get a voltage reading 0.875 for +1db used the formula db = 20(log[v1/v2]). (Hope I used it right I'm not great in maths :roll: )  IS THIS RIGHT?

This sets up the gate of q1 around  -.9 mv.


Seems you're going the wrong way.  Here's the method I used with an addition at the end (kudos to those who posted this initially):

Here is Kdawgs procedure:

Q Bias
Release: Fully CW (Fast)
Attack: Fully CW (Fast)
Input: Fully CCW (off)
Output: Fully CW
Ratio: 1:4
Meter: Bypass
Q bias: fully CCW

Signal Generator: 0.245 V (AC) sine wave 250 Hz
Measuring across input pins 2 and 1 & 3 for ground

1. Turn up input control until I get 0.100 V AC, measuring across output pins 2 and 1 & 3 for ground

2. Rotate Q Bias until reduced to 0.089 V AC across output. [ 1 dB = 20 log (0.100 / 0.089) ]

kdawg, when you adjusted the Q-bias, did you remember to turn the q-bias trimmer fully counter clockwise, before turning up the input control. This is not mentioned on the Gyraf site, but mentioned in the manual. If you forget this you will end up with the problem you describe.

Quote
GR Tracking

I can't get unity gain here it's seems that there isn't enough gain to get the 50mv that I'm putting through.

Am I doing anything wrong in the q bias setting?

cheers


Get the Q-bias setting right and then try again.  When my unit did what yours is doing, it turned out to be a bad Lorlin switch, but it seems highly unlikely that your problem is the same.

Hope some of this helps.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on December 06, 2004, 10:19:57 AM
hi don,

Thanks loads man :thumb:  :thumb: ... one of the 1176 is workin fine now...the other one is not behaving well. I made the qbias settings on the second one but I still cannot reach unity gain when doing  the gr tracking settings and the compression is not working well, it's like compressing for a few seconds then the compression just goes.. any ideas?


cheers
Title: All things G1176 - the new "repost" thread.
Post by: radiance on December 20, 2004, 09:15:03 PM
I'm about to order parts for this project and I was wondering what kind of resistors everybody is using. Are they metal film (1%) resistors? Or are the carbon 5% ones sufficient?
I'm asking because I have some carbon 5% resistors left from the SSL project.

More in general: do metal film resistors make better sound quality because they match the value closer, or because of the stuff they're made of?
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on December 20, 2004, 11:26:35 PM
Quote from: "keithcamilleri"
hi don,

Thanks loads man :thumb:  :thumb: ... one of the 1176 is workin fine now...the other one is not behaving well. I made the qbias settings on the second one but I still cannot reach unity gain when doing  the gr tracking settings and the compression is not working well, it's like compressing for a few seconds then the compression just goes.. any ideas?
cheers


Sorry I didn't respond sooner, but I didn't see this post until now.  For some reason, the email notification must've burped and forgotten to remind me when someone posts to this thread.  

Have you got that second one working yet?  

Radiance:  While I won't get into the audiophile discussion about different resistor types, I think it's safe to say that metal films are generally considered quieter in a circuit.  

Personally, I tend to use metal films in my studio "projects" because of this.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: radiance on December 21, 2004, 08:38:50 AM
Thanks for the answer idylldon.
Title: All things G1176 - the new "repost" thread.
Post by: keithcamilleri on December 21, 2004, 09:10:41 AM
Hi Idylldon,

no luck yet the first one is working great but the second one is not.. it's compressing I know it is because when I set up the qbias full ccw i can hear it working... I'.m a bit lost I can reach unity for the ratio settings...


cheers
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on December 28, 2004, 11:53:44 AM
Hi
I wanna build G1176 but with 0-12. Can I use this circuit with pot like with Lundahl use or I must use dual pot for "T" atenuator like on original schematics.
Also where to find this pot.
Thanks
Duka
Title: All things G1176 - the new "repost" thread.
Post by: Svart on December 28, 2004, 05:24:48 PM
I want to get rid of the meter switch and just run a VU.  I am unclear how to do this and can it be done?  I also have other questions about where wiring goes as i haven't seen any clear diagrams..   where does the input go if you aren't using the input trafo?  what's the 3 pin header next to the output header?  things like that..  i've been trying to read this 34 page thread, and others but i'm sick and drowsy and nothing is making sense today!

I need  :guinness:  :guinness:   :green:
Title: Oops... backwards BD517/518
Post by: kdawg on January 01, 2005, 08:08:00 PM
I accidently put in BD517 and BD518 both backwards on another 1176 I was putting together (Labs V7 board). Anyhow, I smoked R40/41 (4R3 resistors) instantly. So after replacing BD517/518 and R40/41, it still doesn't seem quite right. What else should I replace or check down the signal line? Did this end up putting like 30+ volts on the rest at the junction of R40/41?

Thanks

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on January 01, 2005, 08:35:50 PM
Quote
I want to get rid of the meter switch and just run a VU


Do you mean run it as a VU as in not showing gain reduction.  If so some people say this changes the sound, though I can`t vouch for this.   Some people will only use the meter in VU mode for set up & switch to GR when its actually doing the job so to speak.   The difference is when the meter shows GR it is buffered, but this is not the case in VU mode when it is simply strapped across the output.

Quote
where does the input go if you aren't using the input trafo?


If you`re not using the input transformer then you use the input header that is next to the output.  

What you may find useful is to download the board layout PDF for this project from the GYRAF site. This has the connection details on it.
Title: Re: Oops... backwards BD517/518
Post by: gyraf on January 02, 2005, 05:40:20 AM
Quote from: "kdawg"
I accidently put in BD517 and BD518 both backwards on another 1176 I was putting together (Labs V7 board). Anyhow, I smoked R40/41 (4R3 resistors) instantly. So after replacing BD517/518 and R40/41, it still doesn't seem quite right. What else should I replace or check down the signal line?


The driver transistors feeding the output pair will often be killed as well, when making this mistake..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Svart on January 06, 2005, 05:49:27 PM
thanks Rob!

well i could use it in GR mode more to tell you the truth.  I want to get rid of the switch between gr-vu.  i'm also putting two mono 1176's in one box and would like to use one vu meter also with a swtich to switch the meter between the two.  

any thoughts?
Title: 1/4" jacks
Post by: kdawg on January 06, 2005, 05:51:57 PM
I forgot to ask about this way back when...

I have 1/4" TRS and XLR jacks for input and output, but I never isolated the 1/4" jacks from the chassis. Do I need to even if I don't have any hum problems? I thought this might affect the levels of input when using balanced.

thanks.
-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: Svart on January 06, 2005, 05:54:37 PM
shouldn't need to if you aren't having problems with ground. it shouldn't affect the levels at all unless there is a problem either.

cheers! :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: jensenmann on January 07, 2005, 10:58:23 AM
Hi everybody
I have already two G1176 running with bestsounding result. But I was wondering about the behaviour of the VU and the low output level (using Gustavs PCBs and only hum-cut-mod). Investigating this thing I realized that the original schem on gyraf´s site says 100k for R54(tracking adjust) but the silksceening on Gustav´s PCBs say 500K for R54 and Gyraf´s bill of material says 470k for R54. My boards were stuffed with 500k so I changed them to 100k according to the original schem. This was the solution!!! More output Volume, the meter shows what I hear and the tracking adjust pot is no mor full counterclockwise as it was with 500k.
Any comments?

 :mad:  :guinness:  :sad:  :guinness:  :?  :guinness:  :grin:  :guinness:  :green:
Jens

P.S. Mnats PCBs say 100k on silkscreening and bill of material for R54
P.S.2: heavy thanks to everybody here
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 07, 2005, 11:36:07 AM
jensen,

The 500K in stead of 100K trimmer is just to have a broader adjustment range in case of less-than-brilliant FET matching.

It makes no difference whatsoever - other than that you can dial in the same values, plus some more..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: jensenmann on January 07, 2005, 12:11:31 PM
oops

 :oops:


I promise next time I´ll read the schem before posting subjective thing.
But there is definitely more output volume (because yesterday I installed a new poweramp)  :grin:

cheers
Jens
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 12, 2005, 10:21:36 PM
I might as well post to the big one....

I have signal passing through.  I can turn the input and output and something happens.  I can play with the Q Bias trimmer and it does things.  In fact, I set the Q Bias trimmer without much incident.

When I tried to set the GR (-6db) I set the input and output to 50 mv (1 khz) and then switched to GR mode.  I turn up the input level (the source, of course) and it does not seem to do much.  I can never get have the input level on the output.  I did also notice that there seems to be some GR when I have switched the lorlin to the complete counter clockwise position.  This brought me to the possible conclusion that I have put that in the wrong way.  Could this possibly be what is causing the issue?  I am considering just desoldering it anyway and flipping it just to see what happens...but I am curious if anyone out there has any ideas.

Thanks!
Michael
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on January 13, 2005, 01:35:34 AM
Could someone be so kind as to post an input / output voltage w/test tone of their working G1176... something like:

Freq: 250 HZ
(Un)Balanced Input

Ratio: 1:4
Input Knob: 1/4 up
Input Voltage: 0.72 V (AC)
Output Knob: 1/2 way
Output Voltage:  0.5 V (AC)

Ratio: 1:4
Input Knob: 1/2 way
Input Voltage: 0.72 V (AC)
Output Knob: 1/2 way
Output Voltage:  0.6 V (AC)

Ratio: 1:20
Input Knob: 1/4 up
Input Voltage: 0.72 V (AC)
Output Knob: 1/2 way
Output Voltage:  0.3 V (AC)

Ratio: 1:20
Input Knob: 1/2 way
Input Voltage: 0.72 V (AC)
Output Knob: 1/2 way
Output Voltage:  0.56 V (AC)

I'm just having a heck of a time figuring out why my unit is limiting with basically anything I put into it. It's really unusable right now. Thanks a ton.
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on January 14, 2005, 03:27:35 AM
Could this be my input problem...

BC107 instead of BC107B's? Could that really change the threshold points?

Ic = 2mA, Vce = 5V - hFE for BC107: 110 to 450
Ic = 2mA, Vce = 5V - hFE for BC107B: 200 to 450

f= 1kHz
Ic = 2mA, Vce = 5V - hfe for BC107: 250
Ic = 2mA, Vce = 5V - hfe for BC107B: 300

I want to use these 1176s so bad, but I just can't put any signal from a preamp into it without squashing it like crazy, thus getting really low output. I've used real 1176s and can usually set the input around 10 o'clock, output around 2 o'clock and you're set.

All voltages match the schematic... I've built 4 channels, they all act the same. Definitely BF245A's there.

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 18, 2005, 10:13:58 AM
Quote from: "idylldon"

Here are the voltages I measured for each transistor:

E          B          C
Q2--.51--1.03--1.83
Q3--1.20--1.83--11.85
Q4--11.36--11.96--30.5
Q5--4.41--4.87--28.7
Q6--29.3--28.7--14.47
Q7--30--29.3--14.47
Q8--13.84--14.47--30.5
Q9--13.80--13.19--0.0
Q12--2.38--2.88--9.75
Q13--9.17--9.76--30.5
Q14--1.62--2.17--10.69
Q15--10.15--10.69--30.5


Ok.  I definitely think I have some serious issues in my GR  Control Amp Section.  

For those that did not know what I had to do....I built the board and I think I shorted the 7824 (regulator) and caused some serious things to happen in the circuit.  First, it blew up the 5532 I had in at the time as well as the big 1.1k resistor!  hehe..that was fun.  Anyway, I replaced the 1.1k and the regulator and it powered up great.  I have the 30V/-10V we are looking for.  Then it would not really pass audio.  SO...I changed out the first FET and replaced transistors Q2,3,4.  Now it passes audio just fine. Please note I am also bypassing the 5532 and using the input transformer (lundahl).  Now when I play with the QBias something happens so that is a good sign.  The problem is that it does not really seem to compress the way it is supposed to.  I feared that I might have destroyed some other transistors in the circuit so I checked the voltages.  This is what I found:

E          B          C
Q2--.56--1.09--1.84
Q3--1.20--1.86--12.95
Q4--11.3--11.8-- 29.53
Q5--4.4--4.8--28
Q6--28.5--27.9--14.45
Q7--29.64--28.99--14.73
Q8--13.81--14.48--29.87
Q9--13.77--13.14--0.0
Q12--22.9--8.23--26.60
Q13--25.87--26.33 --30.03
Q14--29.98--4.88--5.45
Q15--4.86--5.45--30.01

When I compared these to some other ones I found listed in this thread (see above quote for one example) Q12,13,14,15 seemed to be WAY off.  This brings me to the conclusion that something is obviously wrong with the GR control amp.  This, obviously, would cause some issues in regards to compression!

Anyway, before I go and replace all these transistors....could something else be happening that I need to check first?  Any input voltages to check?

Thanks!
Michael
Title: All things G1176 - the new "repost" thread.
Post by: Greg on January 18, 2005, 10:30:24 AM
kdawg:
Did you rewire the output tranny for more gain? How is it wired... 2:1, 1:1, 1:2 ???

I rewired mine 1:1 and I like the results... I'm thinking about actually going to 1:2 configuration for even more gain.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 18, 2005, 10:53:44 AM
Michael,

Q12, Q14 looks "most" wrong. Try changing these - check for shorts, component values, and orientation around those.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on January 18, 2005, 11:29:48 AM
Quote from: "kdawg"
Could this be my input problem...
BC107 instead of BC107B's? Could that really change the threshold points?


I'm using BC107 (no suffix) in mine and they seem to work fine.  All measurements are within spec and the calibration went smoothly.  

I also did the 1:2 OT mod, which gave me more output, but I don't think that's what you're up against here.  While the input control is sensitive, I usually end up at the 10:00 position as you mentioned and the ouput anywhere from 12:00 - 2:00.

Anyway, I just wanted to let you know the BC107 work OK in my units to help eliminate something.  I wish I could offer more help, but I'm still at the steep end of this learning curve.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on January 18, 2005, 01:00:03 PM
I have the unit wired 1:2. I'm going to try replacing both Q1 and Q10 FETs, I only socketed the Q1 FET so I'll add another socket.  It seems that the line amp section is working OK, as I can get unity out very easily.

If I remove Q1 and put the unit it GR, should there still be any gain reduction measured on the output?

If I apply a -30db signal (.0245 VRMS, referenced to 0dB = 0.775 VRMS, correct?) unbalanced, + pin 2, - pins 1&3 tied then measure Input Pot Pin 1, I should get 0.245 volts also right?

Then - if I switch to a balanced signal, applying -30dB (do I measure 0.245 VRMS across + to GND or + to -?), + pin 2, - pin 3, ground pin 1 and measure Input Pot Pin 1, I should still have 0.245 volts right?

I'm trying to isolate the 5532 input stage to make sure this isn't a balanced/unbalanced issue.

Thanks everyone for your help!

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 18, 2005, 01:03:04 PM
Quote
If I remove Q1 and put the unit it GR, should there still be any gain reduction measured on the output?


There will not be any gain reduction, but the meter (Q10) will still allow meter to indicate the now-not-happening GR.
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 19, 2005, 10:37:23 AM
Quote from: "heybluez"

E          B          C
Q2--.56--1.09--1.84
Q3--1.20--1.86--12.95
Q4--11.3--11.8-- 29.53
Q5--4.4--4.8--28
Q6--28.5--27.9--14.45
Q7--29.64--28.99--14.73
Q8--13.81--14.48--29.87
Q9--13.77--13.14--0.0
Q12--22.9--8.23--26.60
Q13--25.87--26.33 --30.03
Q14--29.98--4.88--5.45
Q15--4.86--5.45--30.01


Ok I went ahead and replaced Q12,13,14,15 and got the below results:

E          B          C
Q12--22.46--14.81--26.11
Q13--25.58--26.10 --29.25
Q14--4.12--4.78--5.12
Q15--4.52--5.12--29.34

Not much improvement.  I checked all the obvious components orientation, etc.  The caps look fine.  I am checking the poly caps and the resistors now.  I cannot seem to find any shorts...I was trying to be meticulous when I stuffed the board to prevent anything like that...but hey...I am still looking.

My voltages are like 29.8V / -9.5V  I am more converned with the -9.5...I believe that should be closer to ten.

Anyway, I am still looking...any thoughts?

Thanks,
Michael
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 21, 2005, 08:53:38 AM
Quote from: "heybluez"

E          B          C
Q12--22.46--14.81--26.11
Q13--25.58--26.10 --29.25
Q14--4.12--4.78--5.12
Q15--4.52--5.12--29.34


I found the issue!  Here are my new voltages:

E          B          C
Q12--3.94--4.47--14.84
Q13--14.33--14.89 --29.74
Q14--2.91--3.47--16.63
Q15--16.08--16.57--29.70

I checked the orientation of the caps and they looked fine.  I checked the values of the caps and they were ok as well.  SO I figured that since I had changed all the transistors anyway it must a wrong value for a resistor.  I did what Gyraf suggested and looked around Q12-15.  Well, I struck gold when I found that the 270R resistor (next to Q12,13 on the PCB) was not 270R but 270k!  Wow.....oops.  Anyway, I changed that out and my voltages seemed to fall right in place.

I redid the calibration and it seems to work now.  I can see the compression acting with the meter, etc.  I will be probably work on completing it tomorrow or and seeing how it sounds then.

Gyraf...thanks so much for your help!  Amazing what a little thing like a resistor can do!! haha...

Mark..thanks to you as well for my previous signal amp problem.

I do have another question. Where would i find an attack pot like the original.  I am going to wire mine with the push button switches and try to wire in the +8 setting.  I want to put the bypass on the attack switch like the original.  Do you know a) what this switch is called and b) where I could source it?

Thanks!
Michael
Title: All things G1176 - the new "repost" thread.
Post by: holger honda on January 23, 2005, 12:31:31 AM
Hello.
Now I did it!I built two nice board filled with all the goodies.BUT! AHHH!
It turned out that my 24vct was more like 50vct.......that smell....
I ended up with almoust 70v after the bridge.
I quickly realized the mistake and turned the thing off.On one of the boards the r89 resistor got fried.On the other no visble damage.
Now after finding the right transformer I wonder what parts to change.
I guess quite a few.
Any idea of were to start?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 23, 2005, 05:32:11 AM
Hi Holger,

Look at PRR's answer in the other thread you started - http://www.groupdiy.com/index.php?topic=5077

He surely knows his stuff..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: idylldon on January 23, 2005, 08:53:52 PM
C15 is supposed to be 470/40, but I was wondering why the voltage rating is that high since I can't see where it gets near 40?

Seems like 470/35 will work in this position.

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 24, 2005, 04:46:43 AM
It probably will work fine at 35V.

But 40V is what I had at the time, and what I made room for at the pcb..  :razz:

Jakob E.
Title: more gain
Post by: xsmsx on January 25, 2005, 04:27:38 PM
Hi there!
just the right time to post my little problem. My unit works fine but, compared to the original, I don't get enough output gain. I just read about 1:1, 1:2 transformer configuration. What is it about? I alrady exchanged a 11k resistor to 5k, what someone suggested in another thread, but there's not much difference. So what can I do?
Thanx a lot!  

Christoph   :shock:
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on January 25, 2005, 04:44:33 PM
The 1:2 mod gives you more like the gain of the original
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 25, 2005, 10:39:51 PM
Oh man....I think that someone is trying to drive me crazy.

I have pretty much replaced all the FET's and transistors on my board to get it to work.  I think i blew them up when I shorted my regulator a while back.  Anyway, I can set the QBias (using KDawgs procedure) and last night I thought I had.  I did have trouble setting the GR indicator (i.e. -6vdb) and when i would switch ratios it would definitely jump everywhere.  I figure I better change Q10 just in case.  When I did it seemed to work.  I still had some trouble getting to calibrate it but it seemed to not jump anymore.

I had some music playing through it and it seemed to work...at 4 is what not "as loud" as 20 and it looked on the meter to be compressing.

Anyway, I decided to go to bed and box it tonight.  SO....in my brilliance, I figure I changed everything else I might as well just replace the last three transistors just in case..these are Q5,6,7.

Now I don't know if that did something or what!  But not I cannot calibrate to save my life.  The meter jumps again when I switch ratios (i.e. without signal) and I cannot drop it to -6 and keep then calibrate the meter at 0.  It just won't do it.  I did put signal in it and it does seem to compress.

I am so frustrated I had to leave it alone before I tossed it!  Anyway, I was reading in the thread about Orson's troubles with the GR indicator so I will see what I can with that.  I am curious anyone have any ideas as to what I can look at?  I think everything is right?  Could my FDH333's be toast?

By the way, the only time I had it the closest it seems I did not have to turn my QBias more than a little half way...not it is a little more than that.

I did turn these pots just to see if that did anything...i hope I am allowed to do that without damaging anything else!

Anyway, thanks for your help!
-Michael
Title: more gain
Post by: xsmsx on January 26, 2005, 04:15:27 AM
hey Rob,

thanks, that's what I thought. But how do I do this 1:2 modification?

Christoph
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 26, 2005, 04:20:32 AM
Christoph,

Search the Meta.

Michael,

GR jumping (and staying off) when switching ratios, could indicate leaky FDH333's. But it COULD also be component-value problems around point 20/21 - the "threshold offset" for the different ratios.

Jakob E.
Title: more gain
Post by: xsmsx on January 26, 2005, 05:54:10 AM
Hi again,

I think I found it. It describes how to change the connections of the Input AND Output Transformer. I don't have the Input Transformer. So can I just go on changing only connections at the Output transformer? Or do I have to make some more effort?

Thanks again
Christoph
Title: Re: more gain
Post by: idylldon on January 26, 2005, 11:18:42 AM
Quote from: "xsmsx"
Hi again,

I think I found it. It describes how to change the connections of the Input AND Output Transformer. I don't have the Input Transformer. So can I just go on changing only connections at the Output transformer?
Thanks again
Christoph


Yes.  

Cheers,
--
Don
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 26, 2005, 11:31:52 PM
Hi Gyraf,

Just for the record I am using the NTE177 substitute.  In case that matters.

Anyway, I checked the orientation of the 6.8u and 100u caps (C19,20,21) and they seemed ok.  I also switched from 4:1 to 20:1 and measured a DC voltage change at point 7 (on the ratio board where the release and attack are connected) and this did change and stay steady.  I believe it was in the -3.x to -1.x range when i switch back and forth.

How would I tell if the NTE177's are leaking?  I also noticed that the jump is the worst when switching from 4:1.  After that it aint so bad.  I know this worked once...at least I thought it did but I was never able to get the GR tracking to calibrate.  Nonetheless there is obviously a problem.

-Michael
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 27, 2005, 04:39:10 AM
Michael,

We've had several problems with NTE subs - mostly on pin-outs.

I would'nt use any NTE's - it's almost always easier to find a different component with the needed specs - and then you'd know what you got.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on January 27, 2005, 07:49:32 AM
I want to make a 'hard bypass" on my 1176 using 4 relays.
Is it o.k. to use the "VU lamp" power for this?
I'm using a 0,6 A , 2 x 25 V torriod transformer.

Also, if I use four 5V relays (with the coil's powered in series) I will consume less power than four 24V relays (with the coil's powered parallel) right?
Al the realys need to be switched at once so...
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 27, 2005, 09:38:26 AM
Gyraf,

What do you recommend to replace the NTE's?  Anyone know where I can source some FD333's?

Thanks!
Michael
Title: All things G1176 - the new "repost" thread.
Post by: radiance on January 27, 2005, 10:47:57 AM
Quote from: "radiance"
I want to make a 'hard bypass" on my 1176 using 4 relays.
Is it o.k. to use the "VU lamp" power for this?
I'm using a 0,6 A , 2 x 25 V torriod transformer.

Also, if I use four 5V relays (with the coil's powered in series) I will consume less power than four 24V relays (with the coil's powered parallel) right?
Al the realys need to be switched at once so...


Edit: I want to take the "vu lamp" power out which than will be regulated by a 7824 regulator ....
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 28, 2005, 07:46:30 PM
Gyraf,

What do you recommend to replace the NTE's?  Anyone know where I can source some FD333's?

Thanks!
Michael
Title: All things G1176 - the new "repost" thread.
Post by: mnats on January 28, 2005, 08:25:50 PM
Mouser carries them.
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on January 29, 2005, 08:29:02 AM
oops!

sorry that was an
Title: All things G1176 - the new "repost" thread.
Post by: Bauman on January 31, 2005, 06:58:53 PM
Do you guys think a front panel like this with 4 1176 can be too busy??

(http://www.thediypill.phx.com.br/g1176/41176e1272_peq.gif)

INPUT, OUTPUT -> the black ones
grey in the middle is RATIO
other greys are ATTACK and RELEASE

back to drilling...
(the 2U is a Neve 1272... or will be)

 :guinness:
Fabio
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on February 02, 2005, 09:06:02 AM
Howdy,

I replaced my NTE177 with FDH333's.  I was hoping this would fix my meter jumping when switching ratios.  It did not.  It seems that from 4 to 8 is the biggest jump then 8 to 12 and 12 to 20 are much smaller.

I have not recalibrated yet so I am not sure if that would make a difference.

I thought I had it once but the only thing I changed after that was Q5,6,7 cause I was worried that I may have blew them out during my previous fiasco.  I ended changing most if not all of the transistors anyway so I figured what the heck.  New ones won't hurt.  BUT I am not sure how exactly this would affect my meter.

I have checked resistor values and cap orientations, etc and cannot find anything out of the ordinary.  I also took measurements where the FDH333 diodes meet and with the ratio at 4 it was like (~ -3.x) and at 20 (-1.8x).  It held steady so I dont think it is leaking anywhere.

Would you think that I still have a component that is wrong?  Thanks for your help.

-Michael
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 02, 2005, 09:35:22 AM
When you say "meter jumping" - do you mean temporarily or permanent change to the meter indication?

The meter jumping temporarily when switching ratios is normal - it also occurs on "real" 1176's..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on February 02, 2005, 09:39:04 AM
Quote from: "Bauman"
Do you guys think a front panel like this with 4 1176 can be too busy??

(http://www.thediypill.phx.com.br/g1176/41176e1272_peq.gif)

INPUT, OUTPUT -> the black ones
grey in the middle is RATIO
other greys are ATTACK and RELEASE

back to drilling...
(the 2U is a Neve 1272... or will be)

 :guinness:
Fabio


Yes, to me it looks buzy.
What I always do is make a cardboard frontpanel. Just cut out the meter hole, put the meter in place and start arranging those knobs (well, you did that already).
Also, put those caps on the knobs, this might look a little less buzy.
Just make it as real as possible, only from cardboard.
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on February 02, 2005, 10:51:00 AM
Quote from: "gyraf"
When you say "meter jumping" - do you mean temporarily or permanent change to the meter indication?

The meter jumping temporarily when switching ratios is normal - it also occurs on "real" 1176's..

Jakob E.


I mean permanent.  It jumps and stays there.
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on February 02, 2005, 11:05:48 AM
Fabio

If you plan to use the ratio & meter PCB`s be careful that they don`t overlap each other  behind the panel with your  layout.
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on February 03, 2005, 01:10:24 PM
Hello,

Real quick...could Q5,6,7 have anything to do with my meter jumping when I switch ratios?

-Michael
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 03, 2005, 01:15:21 PM
No, they shouldn't.

Your problem must be in the sidechain/metering section - Q12-13-14-15, the two diodes, and the ratio switch, point 20+21.

My primary suspect would be component values/shorts at the ratio switch.

Follow the schematic, and see if everything behaves like predicted in this section.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: hodad on February 04, 2005, 05:00:15 PM
approximately what voltage should I be seeing off of Pin 6 of the TL071?
I'm thinking it's not supposed to be 17 v, which is what I'm getting.

Tom
**   Updating my saga:  with careful manipulation of R55, I can get the meter zeroed momentarily.  But if I shift into bypass mode or turn the unit off,  the calibration goes away.  Plus, for some reason it takes 30 seconds or so for the voltage to the meter to get up to its final value.

Also as well:  I'v only got maybe 5 or 10 degrees of play on R55 before I go down to -7 volts or up to 17 volts.  Is this normal?   Should I check the value of the trimpot, or maybe put in a 10 turn trimmer instead of a single turn?  
***

More updating:  I figured out I had the wrong trimmer at R54--2K instead of 100K.  Fixing that goof got the vu needle to zero up in a lovely fashion.  Now I think I'm actually ready to put audio through it.  


Thanks
Tom
Title: 24V Reg
Post by: thedug on March 27, 2005, 01:14:22 AM
Can anybody explain to me how the 24V regulator is getting 30V.

I assume it has something to do with the voltage devider on the ground pin.


Doug
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 28, 2005, 05:33:36 AM
Doug,

Yep, that's what happens. For a calculation of resistor ratio versus output voltage, see the manufacturer's 78XX data sheets..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: thedug on March 28, 2005, 10:07:21 AM
Why would you choose to do this versus an adj. regulator?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 28, 2005, 11:26:18 AM
Cheap, simple, available, and does the job well enough..
Title: All things G1176 - the new "repost" thread.
Post by: radiance on April 14, 2005, 07:54:58 AM
What is a good way to drop the voltage from the "VU lamp out" from 37V to 9V?
I've never done this before so I'm a bit unsure but what I read from the books is two resistors (with the right value) in series between the two poles.
Is this correct? and should I use 1W or higher resistors for this?

I want to use the "VU lamp out" to power 4 LED's in series instead of using a lamp.
My power transformer is 0,6 A so I guess there's enough juice...
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 14, 2005, 08:26:52 AM
To drop voltage, use a resistor in series with the LED's. The LED's should also be connected in series.

To find resistor value, you need to know voltage drop and current draw.

Give the LED's e.g. 10mA.

There is a voltage drop over each led of say 2V. 4LED's make 8V

You now have 37V that needs to be dropped to 8V - that is a drop of 29V @10mA

U/I=R - 29V/0.01A=2900Ohms. Make that 3.3K, that's close enough.

Power rating - 29V x 0.01A=0.29W - use 0.5W or 1W to have a safe margin..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on April 14, 2005, 09:20:27 AM
Thanks Jakob. Can I do the same for powering two 12V relay's in series? (with a different resistor value obviously)

Also: how about this for powering the relay's..(http://www.rolandklinkenberg.com/ssl/Voltage.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 14, 2005, 11:01:27 AM
Nope, you shouldn't use a divider for that. The load parallels the lower side of the attenuator.

Figure out the current and needed voltage drop, and calculate like above..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: martthie_08 on April 14, 2005, 01:37:07 PM
hey, I just found this on evilbay:

http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=7315367734&fromMakeTrack=true

It is a 1176 with jensen trannies, maybe that would be another nice option in addition to the oeps and lundahls. I sent the auctioneer an email asking about the exact model numbers, will post them here, if I get a reply!

And if you have some 3 grand to spend this blue 1176 looks quite nice :)
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=7314524100&fromMakeTrack=true

Is that an overload or a threshold led on above that meter?
Title: All things G1176 - the new "repost" thread.
Post by: radiance on April 14, 2005, 06:41:15 PM
Thanks again Jakob. It works like a charm :grin:
Title: All things G1176 - the new "repost" thread.
Post by: radiance on April 19, 2005, 03:26:24 PM
OK, for the relay's it worked, but the LED's are not working this way.
They are 2,1 V  and 20 mA LED's (well it sais If nom.=20mA, I don't know what that means)

They don't even light up with no resistor in series. Are they drawing to much currend?

Also, they DO light up when connected to a wall wart power supply set to 9V. This is a regulated power supply and it is rated 1000 mA (12 VA)  max.

What is it with the 1176 lamp out power that it will not light my LED's?
Title: All things G1176 - the new "repost" thread.
Post by: radiance on April 20, 2005, 06:42:02 AM
OK, I found it. I'm working on a stereo version of the 1176 and I have two toroit power trannies. I also have a relay bypass and to power the relay's  I use both lamp out's from the two boards to even the load. To power the LED's I took power from one off the lamp outs, well, thats what I thought I did (it's a birds nest in there). What I actually did was take the ground from one lamp out and the +V from the other one. Since I had not properly grounded the unit yet I had two separate grounds and that was the reason the LED's where not lighting up.
It was really confusing to get 37 V on the multimeter and no response from the LED's..
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on April 20, 2005, 08:57:54 AM
Hi
Too I have two question:
What transformer (wattage) to use for Dual?
I have Sifam 19WF with his festoon 12V lamp.
How to got voltage for this lamp. I mean best way.
Thanks Duka
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 20, 2005, 09:04:02 AM
Duka,

Read the thread. Do some calculations. All the needed info is already there.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on April 20, 2005, 11:06:43 AM
Quote from: "gyraf"
Duka,

Read the thread. Do some calculations. All the needed info is already there.

Jakob E.

Hi
I read the thread!!!!
Yes, I read the thread :grin:

We teach from clever and from expert.
I make some math. If I wrong tell me.
My lamps are 12V - 0,1A. E.g. if I want to wire lamps in series I need to drop from 37 to 24V. Current stay same 0,1A. 37V-24=13V. Than 13V/0,1A=130ohm (next 150ohm).  And on the end 13Vx0,1A=1,3W (2W).

If I want to use two lamps in parallel. I must drop to 12V.
Does current is 0,2A ?first dillema :?
If is it 0,2A I find 125ohm - 5W.

Also about transformer, I find a different value. I know I cant make mistake to use bigger.  I find for single 2x25V 500mA. Is it 25VA or 12,5VA. In fact I must use doubled current for dual.
Thanks
Duka
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 20, 2005, 12:06:44 PM
:thumb:  Well done..!
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on April 20, 2005, 12:08:56 PM
Quote from: "gyraf"
:thumb:  Well done..!

What about transformer :sad:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 20, 2005, 12:11:04 PM
2x25V 500mA is - straight forward -  (2x) 25V/500mA, that is 2x25x0.5 =25VA
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on April 20, 2005, 01:14:52 PM
Quote from: "gyraf"
2x25V 500mA is - straight forward -  (2x) 25V/500mA, that is 2x25x0.5 =25VA

Thanks :thumb:
Is it enought 50VA for Dual?
Duka
Title: All things G1176 - the new "repost" thread.
Post by: keninverse on April 22, 2005, 09:26:01 AM
Hi guys,
first time poster...I'm in process of building a 2 x 1176 and I have all the parts amassed with the exception of the AL29 VU.  I have several AL39s that I pulled some time ago but I was wondering can you use these larger meters without modifying the meter driver?  Will I just see a slightly slower response on the meter if i leave the circuit stock?


ken
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on April 22, 2005, 01:49:31 PM
I have a Sifam w/24V Festoon Lamp @ .125 A... now I see what's going on above tapping the Lamp Power w/resistor, but can I just tap after the 24V Regulator or is that a bad idea? Thanks

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 23, 2005, 06:23:31 AM
Ken,

If your AL39 are true VU-meters, they should work fine as-is. Look at and compare the data sheets for these.

Kdaw,

It's NOT a 24V regulator, it's a 30V regulator. Yes, it uses a 7824, but it is offset to +30.

Don't load the +30V line more than it already is - better use the unstabilized DC (or the AC) with suitable dropping resistors.. See previous pages for the calculation.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: keninverse on April 23, 2005, 11:37:41 AM
Thanks Jakob,
Looking at the datasheet, the only difference I see b/w the AL29 and AL39 is rise time (~0.01s).


ken
Title: All things G1176 - the new "repost" thread.
Post by: radiance on April 24, 2005, 01:35:32 PM
In my 1176 I have used polyester caps for C1, C10, C17, C5 and C27.
Will I hear any difference when I change these for say Wima polypropylene cap's ? I mean is it worth it?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 25, 2005, 03:05:25 AM
no
Title: All things G1176 - the new "repost" thread.
Post by: kdawg on April 26, 2005, 04:03:55 AM
I decided to build an MNAT version of the 1176 and it went together smoothly. I ducked, then flipped the power switch. No flames or flying capacitors. I even have all the voltages OK off of Gyraf's schematic. The meter even zeros on GR. BUT - R87 (the 1 Watt 1K1 resistor in the power supply) gets VERY warm, like I can't leave my finger on it for more than a second.

I thought it was my meter lamp drawing, but its disconnected and I still have the problem.

Where should I start? Too much current draw from something... no obvious shorts. 30 volt rail is solid. 7824 doesn't get too hot.   Thanks

-kdawg
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 26, 2005, 04:10:48 AM
the 1W resistor will get hot. That's why it's 1W after all  :grin:

If you're unsure about the dissipated power over the resistor, simply measure voltage across it and calculate...

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: lumpylipton on April 29, 2005, 05:38:16 PM
Hi Jakob and gang,

I've nearly got my first 1176 working, but I need some help.  All my transistor voltages look good, it works great at a line amp (signal passes through and input and output pots increase/decrease gain), but it seems it's not compressing, and I can't get the VU in GR mode to go near 0, it's way short of that regardless of where the trims are set (it moves, just not nearly far enough).  I have replaced the FETS and the TL071 with no change at all, and I know my meter is a real VU (it works as expected in displaying output and is a NOS Dyson).  

In previous posts in this thread, Jakob made mention of points 21 and 19 and DC voltages.  My DC voltages at those points are different as expected(the diodes are conducting) and they do change with Q-bias changing.  However, the DC voltages do not change at all when changing the input level.  As I understood the thread, they should right?

More info:  I have signal traced through, and I see signal at the gate of Q1, but not at the gate of Q10.

Any clues would be be much appreciated.  Thanks.

Warren
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 30, 2005, 01:26:50 PM
Quote
More info: I have signal traced through, and I see signal at the gate of Q1, but not at the gate of Q10.


Q1 has a bit of audio on it's gate to compensate for distortion. Q10 isn't in audio, so here we don't care.

What is interesting is if what kind of DC you have on the gates.

Try tracing ac signal through the sidechain amplifiers and diodes, and check that DC alters with signal level.

And as usually, check for right components, shorts, and such..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Hulk on May 01, 2005, 03:21:21 PM
I'm going to build a G1176 :cool:

Can I use this (http://www.vejle-rc.dk/web-shop.asp?showItem=2377) PSU for the G1176???? :guinness:  :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on May 01, 2005, 03:58:24 PM
Yep, that will probably work just fine.. (the 2x24V version - the one in the pic is a 15V)

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Hulk on May 01, 2005, 04:16:07 PM
Great!

Thanks Jakob!
Title: All things G1176 - the new "repost" thread.
Post by: lumpylipton on May 02, 2005, 02:01:10 PM
Jakob,
Thanks for your response and tips, I can trace the AC signal through all the sidechain transistors and diodes and it's present everywhere.   However, the DC on the gates does not change with varying input levels.  On Q1 gate is 6 volts DC and on Q10 gate it is 0.6 VDC.  Any specific areas to concentrate on, knowing this isn't right?  I have checked resistor values twice, and my voltages look fine everywhere, which is what makes this problem so frustrating.  What range of VDC should I be seeing on the gates?
Thanks again,
Warren
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on May 03, 2005, 01:37:22 AM
Look around the FD333 diodes - that's where your AC gets to be DC..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Mbira on May 11, 2005, 10:15:38 PM
Gah-  I got thru the first four or five pages of this thread-I can't handle reading any more of it right now-My 1176 has already been giving me a headache.  

I'm using the pushbutton version of mnats-IE, no +8 setting.

I don't think my attack and release are working correctly.  

My "GR" button when pushed climbs up until it pegs the top no matter what I do with the trim-pot.

I think I got the bias set correctly.  

I don't know if my ratio buttons do.

I'm lost.  I'm confused.  I'm tired and frustrated.  

I have some voltages from various places.  One area that doesn't seem right is my 5532 gives me this:

15.04
15.04
14.95
0
30.03
15.04
15.04
14.98

My TL071 gives me:

-9.92
0
0
-10.12
0
17.26
7.84
-9.92

By the way, my input voltage after the diodes and before the 7824 is 31.96V

Sorry I'm so grumpy.
This thread is almost 40 pages long.  Hopefully I will have a happy chapter here.

I checked the push-button boards and don't see any shorts.

I'm gonna go eat now and I'll be back...
This is my first day of summer though!  WOOHOO!

Joel
Title: All things G1176 - the new "repost" thread.
Post by: bubba_b on May 20, 2005, 06:49:32 PM
I'm building the mnats board (rev. H) right now and I've wired up a "slam" mode switch as per jakob's instructions on his site. I want to hook up a simple red LED to light up when the "slam" mode is enabled. Where would I hook this thing up?
Title: All things G1176 - the new "repost" thread.
Post by: bubba_b on May 23, 2005, 12:37:55 PM
bump, please.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on May 23, 2005, 12:53:14 PM
use a switch with more decks?
Title: All things G1176 - the new "repost" thread.
Post by: bubba_b on May 23, 2005, 12:58:52 PM
You mean like a dual-pole, triple throw? Not sure I understand. Where would it get power from?
Title: All things G1176 - the new "repost" thread.
Post by: bubba_b on May 23, 2005, 02:56:13 PM
Ok, I tried hooking it up with the meter light and one leg going through one side of the slam switch and it worked. However, with the switch off, it's still lighting up a tiny bit. By doing this, am I putting the led in the ratio circuit and if so, how will that affect operation?
Title: All things G1176 - the new "repost" thread.
Post by: yan_b on May 23, 2005, 03:44:50 PM
Quote
You mean like a dual-pole


triple pole.


the third pole will use for the led on/off switching .
find dc source in the circuit, and dont forget droping resistor acording to
the voltage (for the led)

the pole you use to control the led is completely isolated from the circuit,
one leg come from dc source, and one goes to the led and then to 0v/circuit ground.
Title: All things G1176 - the new "repost" thread.
Post by: bubba_b on May 24, 2005, 02:06:55 PM
Thanks, Yan. It works perfectly. Now I'm just waiting on a meter.....
Title: All things G1176 - the new "repost" thread.
Post by: soundguy on May 26, 2005, 02:57:24 PM
Im having a sh*tty two days.

working on the G1176 on mnats revg board, here's a little history-

I couldnt get the line amp working right, while the line amp wasnt functioning, the meter driver amp seemed to be fine, in GR mode I could get the VU to sit at zero, no problem.

I had the two 180K resistors installed in place of the 180r in the line amp and once I got that straightened out, the line amp works fine now, but the unit wont compress and I now the meter circuit is wack.

Overall, my voltages on the transistors seem about normal.  Ive replaced the tl071 and get the same thing.  The unit wont compress and the GR will only sit at -4ish dB.  GR meter zero pot has no effect, Q bias has no effect and the track pot will move the needle a little but there is clearly something wrong.  Ive triple checked my caps, they seem good.  Power supply is working fine.  Diodes all seem like they are in the right way.  I havent been able to yet find a bad resistor.  Im pretty stumped.  Is there something that seems like I should obviously check?  Nothing is jumping out at me so far.

could any of this be tied to shorts in the ratio selector switch?

Any ideas here are greatly appreciated!

dave
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on May 31, 2005, 10:56:44 AM
Hey Guys

I skimmed through all 40 pages, and I want to verify my toroid is correct (I got this from a BOM listed a while back).  

Digi-Key part # TE62052-nd

12V @ 1.25A

Is this right?  For some reason a voice in my head keeps saying "this is wrong... this is wrong".  

 :shock:

thanks
Title: All things G1176 - the new "repost" thread.
Post by: radiance on May 31, 2005, 11:15:23 AM
Quote from: "soundguy"
......


could any of this be tied to shorts in the ratio selector switch?

Any ideas here are greatly appreciated!

dave


The ratio switch is the first thing I would look at. Check  resistor values off R2, R23, R24, R25  and R26.
Also check around the ratio switch and your bypass switch for shorts to ground.  When in bypass mode, the GR control signal is shorted to ground.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on May 31, 2005, 11:22:37 AM
David,

You need a 2x24V transformer (or better, a 2x30V transformer if possible) for the 1176.

12V is not enough..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: radiance on May 31, 2005, 11:23:32 AM
Quote from: "cannikin"
Hey Guys

I skimmed through all 40 pages, and I want to verify my toroid is correct (I got this from a BOM listed a while back).  

Digi-Key part # TE62052-nd

12V @ 1.25A

Is this right?  For some reason a voice in my head keeps saying "this is wrong... this is wrong".  

 :shock:

thanks


Reading through the data sheet it seems that your 62052 is 2 X 12 v.
For the 1176 u need a 2 X 24v one...



Aaahhh I see , answered already by Jakob.
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on May 31, 2005, 11:31:57 AM
Thanks Jakob and radiance
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on May 31, 2005, 11:46:36 AM
I found these listed Here: http://www.groupdiy.com/index.php?topic=372

TE62055-ND   
Toroid 22V .682A Wires


TE62045-ND
TRANSFRMR TOROID 22V .454A Wires

any thoughts as to which is the better option?

All the 2x24V at Digikey are non-stock and 100 bucks a pop.
Thanks again.
Title: All things G1176 - the new "repost" thread.
Post by: soundguy on May 31, 2005, 01:29:28 PM
avel lindberg has a torroid that will work.

dave
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 01, 2005, 02:59:00 AM
2x22V is too small - we want 30V regulated plus a bit for the regulator. 2x24V is minimum.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Xopek on June 01, 2005, 05:29:25 AM
Small question:

What about  a current on secondary windings?
2x24 V @ ??? mA  ?
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on June 01, 2005, 10:31:57 AM
This is a general post for all the North American peeps that might be building the G1176 and trying to find the correct Toroid Transformer.  

Here is what I got:

30Va Load, 25 + 25 Secondary V, .60A  Secondary Current

http://www.avellindberg.com/

Part Number: Y236106
$22.47
They accept MC/Visa
1-800-979-1022
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 01, 2005, 10:45:23 AM
Thanks, David!

  :thumb:

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 08, 2005, 08:41:47 AM
ok.

i have my boards from mnats.  i just have a question on the PSU, following on from cannikan's post (30Va Load, 25 + 25 Secondary V, .60A Secondary Current)

we're 240VAC here - does the load on primary or secondary change for 240VAC????

hope to hear from you.

chris.
Title: finding the FET
Post by: mfdu on June 10, 2005, 10:18:07 PM
i've been getting all the bits together and will soon be at PSU checking time.  been building two boards side by side, destined for two mono boxes.

got a pair of toroidal 24+24 160VA from jaycar quoted at "OP=0-25V(3.2A) 0-25V(3.2A)" - they should be right, yeah?  was the closest they seemed to have.

having real trouble locating the FET BF245A.  i've also lucked out on any of the supposed equivalents BFW61, BFS72, 2N3819 and 2N3823.  do you know of any suppliers?  please let me know.

i contacted control devices in sydney re. the lundahl LL5402 output trannies, and they're saying $158.40AUD for two.  ouch.  
haven't checked the current price of the OEP's yet.  but since it seems there's no real price difference i reckon i may as well build a lundahl and an OEP, so i have the two flavours.

on board A, i think i may have stuffed the solder on C5 (220n) - on the non-optioned end!  i put the wrong cap in, and then when removing, a heap of excess solder came out on the legs.
can i peg that end of the cap to the resistor R9, or should i just scratch some coating off beside C5 to reveal the circuit layer and give a decent join?

there you go.  here's hoping.  i cant wait for replies - getting back into it.

chris.
Title: Re: finding the FET
Post by: dukasound on June 12, 2005, 02:34:33 AM
Hi
What quality of C15 - 470uF/40V I must use in my 1176?
Too, caps in signal path?
Also  used both optional caps: 1000uF and 100uF with 0,1uF poly in parallel on my board. I hope it is better solution?
Still havent chassis and a pair or resistors.
I will use this equipment with my soundcard with 10K input.
Must I put 620 ohm over output?
Duka
Soon pics
Title: All things G1176 - the new "repost" thread.
Post by: Boulty on June 13, 2005, 09:06:34 PM
Hi, I was wondering if anyone can help me out with sourcing all the parts in the UK to make this?  I have looked through a lot of this thread and couldn't see anything related to this.

I can find most of the parts but some I am having trouble with so all help is appreciated

thanks
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 14, 2005, 02:43:21 AM
Sourcing the stuff is a part of the fun.

We don't want to make "complete kits" that takes no effort for the builder to throw together, just to save money.

Think of sourcing the stuff as an educational experience - you'll be much better off at a later time when you need to find stuff for your own projects, if you go through the trouble of finding the right components now.

What parts specifically do you have trouble with?

Jakob E.
Title: Re: finding the FET
Post by: mnats on June 14, 2005, 08:20:53 AM
Quote from: "mfdu"
got a pair of toroidal 24+24 160VA from jaycar quoted at "OP=0-25V(3.2A) 0-25V(3.2A)" - they should be right, yeah?  was the closest they seemed to have.

having real trouble locating the FET BF245A.  i've also lucked out on any of the supposed equivalents BFW61, BFS72, 2N3819 and 2N3823.  do you know of any suppliers?  please let me know.

i contacted control devices in sydney re. the lundahl LL5402 output trannies, and they're saying $158.40AUD for two.  ouch.  
haven't checked the current price of the OEP's yet.  but since it seems there's no real price difference i reckon i may as well build a lundahl and an OEP, so i have the two flavours.

there you go.  here's hoping.  i cant wait for replies - getting back into it.

chris.


Chris, it looks like you emailed these same questions directly to me the same day you also posted them here.

I can't speak for everyone, but for me DIY isn't about getting all your questions answered for you but rather it's about learning and discovering things for yourself. Still, the questions that you ask are pretty easily answered if you just take the time to look. The FET sourcing question is answered on my 1176 site. There are two Australian sources listed right on my page. The prices for the Lundahl transformers shouldn't have come as a surprise either if you had looked at my page.

I guess my suggestion to you would be to relax, take some time and do some reading about the 1176 project. Jakob did a lot of work to make the project as easy to successfully complete as possible but you need to read and understand the information he and many others have contributed to be able to make one yourself. There are 41 pages just in this thread. Have you looked at Orson's site? Or the 1176 meta?

You will end up saving some money too in the long run...on power transformers at least :wink:
Title: All things G1176 - the new "repost" thread.
Post by: Boulty on June 14, 2005, 09:21:07 AM
It has been fun trying to find the parts, just it is getting frustrating that I can't find certain ones :)

LM7824 24V VOLTAGE REGULATOR

some of the resistors:
4.3R, 38k3,44k2 and 182k

electrolytic 6u8/35w

and I cant find any of the pots grr.. I probably just suck at searching :)
Title: All things G1176 - the new "repost" thread.
Post by: radiance on June 14, 2005, 12:10:25 PM
Where are you @?
Title: All things G1176 - the new "repost" thread.
Post by: Boulty on June 14, 2005, 03:01:04 PM
I'm in the UK, england.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 14, 2005, 07:18:09 PM
mnats - i have the +30V where i should, the -10V where is should and everything is looking great.  reviewing you info on output trannies, i see now my mistake.  no problems.  dont get me wrong - i have had a ball doing these projects, and look forward to building some weak joe's and ssl mix comps next.  as you can see - relax is a word i am unfamiliar with.

will post photos soon.

only problem is tracking down the FET BF245A - will re-read your site and see if my blind-spot has changed position today?!!?! [r.s. australia - i see it now] judging by all the great info you have there, i'm sure everything is answered.

boulty - the voltage regulator is available from jaycar.com.au here is oz - dunno if that helps. . .

gyraf - you are totally right - sourcing the parts IS half the fun.  the kind of fun that can end in tears, but fun none the less.  i've had a great time building these two units, my wife has had a chance to read a book, and i may have even learnt something.
do you do weak joe (aka joe cheap et.al.) PCB's?  planning my next build.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 14, 2005, 11:09:33 PM
ok.

RS international in sydney (the only ones i could find with that name) dont supply components - they do laminating machines.

[edited]  ok.  i'm sorry.  i have found RS australia finally.  sorry to all.

i found https://www.partsvault.com/partsvault/ who seem to have access to pretty much everything - multiple BF245A's from phillips, fairchild et. al.

so a shout out to all aussies - maybe try "parts vault" for your FET's and IC's?  have just lodged a query with them (awaiting response) so can't say for certain, but here's hoping. . .

chris.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 15, 2005, 04:17:54 AM
Quote from: "Boulty"
It has been fun trying to find the parts, just it is getting frustrating that I can't find certain ones :)

LM7824 24V VOLTAGE REGULATOR

some of the resistors:
4.3R, 38k3,44k2 and 182k

electrolytic 6u8/35w

and I cant find any of the pots grr.. I probably just suck at searching :)


I'm pretty sure we've discussed all this before:

7824 - any 24V/1A will do, e.g. http://cpc.farnell.com/jsp/home/homepage.jsp - stock no# SCMC7824CT

For the resistors, remember that we do not specify 1%. Original was built with 5-10% types - so we can just go for nearest value and still be within limits:

4R3  - use 4R7
38K8 - use 39k
44k2 - use 47k (or 43K if available)
182k - use 180k

Electrolytic 6u8 - use 10uF. It's used as DC-blocking only, 6u8 was cheaper than 10u at the time of design.

Jakob E.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Xopek on June 15, 2005, 06:27:00 AM
I could not find 5 mOm pot in the my country...
Whether It is possible to replace it with the switch?
If yes, how many approximately positions it should have and what values of resistors?

In advance thanks for the answer  :sam:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 15, 2005, 06:39:07 AM
Xopek,

yes, you can use a switch in stead of the 5M pot.

experiment with different values to find the release-times you want.

then solder these resistors on the switch.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Xopek on June 15, 2005, 06:45:37 AM
TNX gyraf
I shall try
 :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 15, 2005, 07:02:01 PM
gyraf

i'm happy to see you advise the same substitute values that i ended up using (39k, 43k etc)

after a bit of frustration i think i have found 5M pots here in australia - happy happy.

got my VU meters delivered yesturday - yay.  made the mistake of ordering wafer switches for the meter and gain reduction - they dont fit the PCB.  no biggie - $1.50 per switch.  but just something to be aware of i guess . . .

and now have found that RS components have the OEP output tranny for cheaper $40 AUD.  + $10 delivery.  if (as mnats says) i dont need the screning can, then we're talking half the price of the lundahl.  ordered.  only thing that remains is collecting the 5M pots and drilling the second rack case.

total cost per unit will be about $250 all up, and three days to build the two(would'a been less, if i had'a got all the parts straight off, instead of a couple of errors and stuff).

will post photos soon.

chris.
Title: power transformer
Post by: jho-audio on June 16, 2005, 11:24:56 PM
Hi there,

I have a 66vct (33x2) toroid sitting here, 120VA.  Is this too much for my two G1176 boards?

Thanks, Jason
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 17, 2005, 12:44:50 PM
Jason,

I think it is too large. 160VA is huge overkill anyway. With the 33V, your regulators will probably get VERY hot.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: jho-audio on June 17, 2005, 03:19:45 PM
Thanks again Jacob!  I found a surplus store close by with two 26x2 torroids and will grab those on my way home.

Cheers, Jason
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 18, 2005, 07:15:53 PM
ok.

got my first 1176 on the test bench.

i had the bd135 and bd316 (Q8/Q9) in the wrong way around and they got *a little hot*.  i think i fried them... testing unit with 1kHz signal, not giving any output.
also trying to get GR meter zero to behave - trimpot doesn't have any impact on GR meter level.
but apart from those *little* problems, very happy, and got unit #2 to fit into case as soon as i have fault fixed unit #1.

anyway, it LOOKS great, and will sound just as good real soon.  lets see if i can get a photo linked :

(http://home.alphalink.com.au/~mfdu/public_html/images/1176_in_testing.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 20, 2005, 03:49:41 AM
M.F.D.U.,

the transistors WILL fry if put in reversed. And what's worse, they will often also kill the previous (driver) transistor (s)

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Piotr on June 20, 2005, 02:29:26 PM
Hi, I've been considering for some time the construction of some Gyraf projects, I stumbled accross Mnats' 1176LN which seems a great addition  but I still have one question remaining: how are the units interfacing with mixers ?

Depending on the mixer, inserts might be either at +4 dBu or -10 dBV, either balanced or not. Let me know if you've considered this question... What's the input and output of those projects ? Wouldn't it be a good idea to deal with this issue, for example by providing the usual switch to match the units I/O with the console's insert type.

I have a old Soundtracs Solo Logic 24 on which the inserts are unbalanced and at -10 dBV so I just fear gear that's only set to work with +4 dBu. Thanks, I am waiting for your opinions... Piotr
Title: All things G1176 - the new "repost" thread.
Post by: orson whitfield on June 20, 2005, 09:42:16 PM
Would anyone sell me a few matched BF245As?  I only have time to DIY during the summers and I'd really like to finish my two G1176s.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 21, 2005, 01:39:45 AM
Piotr,

That shouldn't be necessary.

After all, the original 1176 never had -10/+4 switches, which nobody complained about..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 21, 2005, 07:56:46 AM
Quote


the transistors WILL fry if put in reversed. And what's worse, they will often also kill the previous (driver) transistor (s)


hi gyraf.  thanks for getting back to me.

yes - i done gone let the magic smoke out of Q8/Q9.

i guess i can assume Q7 (BC560) is toast too?  what about the rest of the build and components?

well, she is passing audio with ample gain control thru the pots, so i guess that bodes well.

unit two hasn't suffered the same torments at my hands.  that one hasn't been fitted into a case yet, so has had the BC135/136 direction corrected. before being powered up.

thanks again.  will post when got both units firing (as opposed to smoking).  next up - GSSL.

chris.
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on June 21, 2005, 07:43:33 PM
Hey Guys,

I'm in the home stretch of building my G1176.   the unfortunate thing is R36
100R resistor 1/4 Watt keeps frying... I have no idea what is causing this to happen..

any thoughts are greatly appreciated.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 22, 2005, 12:01:04 AM
i am assuming i have fried Q7 when i let the smoke out of Q8 and Q9.

i have been told the BC557 is an equiv replacement for the BC560 in Q7.  seems like that may be the case - anyone care to confirm?

hope to hear from yerz . . .

i have yet to test unit#2 - too busy in sessions.  i expect everything will be tickety-boo tho.

[edited]
unit #2 appears to be operating fine, but having some meter calibration issues which i'm working through (using http://www.altronics.com.au/index.asp?area=item&id=Q0490 and the info on that page is all i've been able to find on it)

chris.
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on June 22, 2005, 11:20:16 PM
Hey guys;

I have the Mnats PCbs (version H) using Lundahl input and output transformers and omitted the components suggested on mnats site.   Upon power up R36 (100R) keeps burning out within seconds of powering up the unit.  I have checked for shorts, solder bridges and polarity of caps.. everything is correct.  

I am using a 30Va Load, 25 + 25 Secondary V, .60A Secondary Current for the power trannie.  and getting a reading of 29.9Vac and .65A DC out of the Power Trannie.

ANy thoughts as to why R36 is frying would greatly be appreciated.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 23, 2005, 01:39:09 AM
R36 burns if there's shorts, wrong resistors or transistors, or wrongly oriented (or failed) transistors.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 23, 2005, 02:38:38 AM
gyraf

i suspect then that you have answered both my query and also cannikin's.

R36 is the weak point - no worries.  so my Q7 should still be apples?  well i'll be dropping in replacement Q8/Q9 tonight.

i now suspect the orientation of the two tantalum caps (C19/C20).  will check this evening also.  should be ok as i dont believe i let the magic smoke out.

now accumulating parts for the GSSL project.  

chris.

p.s. my wife wishes to say thank you all for keeping me out of her hair and giving her a chance to read a couple of books!
Title: g1176
Post by: spacecho on June 23, 2005, 08:14:57 AM
hey guys,

how important is it to 'match' the transistors? I read Gyraf mentioning that we will need sockets for the BF245 fets. Is this for swapping around (matching) purposes?

if yes, which ones?

is a multimeter okay when testing their values, and is their a desired reading for each transistor type? or is it more about matching particular transistor values with each other?

i have bought a whole heap of the transistors for a group diy with 4 of my buddies. We are building a pair each, but got a second pair for the future and a futher single set for contingency. So we have 25sets of parts to mix and match if necessary.

hi m.f.d.u

harry here (turtlerock forum)

will start building this week, i'm in the se suburbs too, so maybe we should catch up and compare, tech units if necesary.

thanks to Jakob and Mako for all their great work.
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on June 23, 2005, 08:21:20 AM
thanks jakob, I'll check again :guinness:  :guinness:
Title: Re: g1176
Post by: gyraf on June 23, 2005, 09:24:21 AM
Hi harry,

Quote from: "spacecho"

how important is it to 'match' the transistors? I read Gyraf mentioning that we will need sockets for the BF245 fets. Is this for swapping around (matching) purposes?

if yes, which ones?


uhm... the BF245's?

I suggest you read the posts in the 1176-meta, we've covered this several times now.

The idea is to have FET's that track regarding gain reduction in GR and VCA positions, so that the meter (in gr mode) reflects what's going on. Also, if you want to be able to use the units as stereo tracking, you should match FET's for similar GR for a given input level.


Quote
thanks to Jakob and Mako for all their great work.


You're welcome - but who is Mako?
Title: Re: g1176
Post by: cannikin on June 23, 2005, 09:46:10 AM
Quote from: "gyraf"

Quote
thanks to Jakob and Mako for all their great work.


You're welcome - but who is Mako?


Mako is mnats.  

Ok I'm off to check my G1176 and find my errors...

Cheers
 :sam:
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on June 23, 2005, 12:52:49 PM
Ok after using a magnifying glass I found my silly error..

amazing how a solder bridge can ruin your day... not to mention your unit :mad:

I have a sifam meter which the lamp box is rated 12V 1/2W and I checked the Voltage coming off the VU Lamp terminals on the main board and it reads 38.5Vdc

what is the best  to bring that voltage down to at least 12V?
Title: All things G1176 - the new "repost" thread.
Post by: Greg on June 23, 2005, 01:55:28 PM
Just use a series resistor. You can make the calcualtion or just use a pot and adjust... then measure and replace with a resistor. I usually just use a pot. Also, I'd recommend running a little bit under 12V... the bulb will last much longer.
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 23, 2005, 06:35:38 PM
hi harry - sorry, spacecho.  i have ole' yella up and running pretty much ok, and am getting big red fitted into a case today.
i'd be happy to meet up and compare - it'd be nice to turn this global into a local, you know?  esp. since i missed the last melbourne engineers drinkies night . . .  emailo me or sommat, ok?

ole yella and big red?  well, i burnt out the lamps in both meters, so used an in series resistor and a couple of LED's - the colours reflect the name of each unit!

during my build, i tested resistors and capacitors, but didn't go around fitting sockets for semiconductors.  i mean - i want character from my units - if the are a little "emotional" at times, then thats fine by me.  ideally the two units i have built so far will have different characteristics.  next pair of mono units i build will be using the lundahl trannie instead of OEP.  but then, maybe i'll try a couple of joe meeks?

yes i had the tanty caps backwards.  fixed now.  doesn't seem like any damage done (on yella, at any rate - red is the one that i fried the bd135/bd136 trans)  once both units are in cases then i'll begin properly testing and will post results.  i think cannikan's magnifying glass would'a come in handy!!!

i dont have a publik access server, and thus cant post images.  can anyone host a photo of my pair of finished units??  i'd like to show off. . .

:)
c.
Title: All things G1176 - the new "repost" thread.
Post by: Neeno on June 24, 2005, 05:58:14 AM
Hi ppl !
I'm almost finished my first two 1176. I used mnats boards rev H.
After some problem solving (bad resistors and wiring) the unit seems to work properly...

I've done the calibration using the original 1176 manual from Gyraf (the guru) website... Finally GR works...

I've connected the compressor to a unbalanced soundcard, i use nuendo 3 so it's configured to work as an external FX.

The problem:
The signal on the input seems to be low, i have to turn the input pot to 12-18 to get compression (almost full CW) and the opposite on the output pot, the level seems too high... i can't turn it more then 48-36 (almost CCW) or i'll get a too hot signal on the output.

Any suggestion ???

P.S.: sorry for my bad english...  :cry:

Neeeeeeeeeeeeeno
Title: All things G1176 - the new "repost" thread.
Post by: cannikin on June 24, 2005, 07:27:27 AM
Neeno,

Are using both input and output Transformers?  just curious.  I'm building version H of mnats pcbs and currently at the point of rewiring it ... I didn't do something right.  

got any tips for wiring or something you learned that wasn't that obvious?

Anyway congratulations!! :green:  :thumb:  :sam:
Title: All things G1176 - the new "repost" thread.
Post by: Neeno on June 24, 2005, 07:51:28 AM
Hi cannikin !
Thank you !  :guinness:

I choosed to use only the ouput transformer (LL5402) and 5532 on input...

I've followed the wiring instructions provided by mnats because i've used interlocked pushbuttons...

Wiring is not so difficoult, take your time and read all the wiring instructions before you start, and don't forget to print a copy of the schematics on A3 sheet !!!  :grin:  

Neeeeeeno
Title: All things G1176 - the new "repost" thread.
Post by: spacecho on June 24, 2005, 09:42:34 PM
Hi all,

i have been reading through the posts as suggested, thanks Jakob, i was wondering, (might have missed a post) how much (VA) my power transformer needs to power 2 units in one box? i know that it needs to provide 500ma for one unit so 1amp for 2 units seems logical.. I can only seem to find torrodial transformers that come in a bigger size that is 3amps (80va) is this overkill, and will such a huge transformer create more inteference?

m.f.d.u,

where did u get your power transformer and 5Mohm and trimpots from?

thanks
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on June 25, 2005, 06:52:36 PM
spacecho

my power transformer came from jaycar - just their 24V torroidal.  i was worried it was way too powerful (3.2A) but all is good on the mono units now that i've got a resistor in on the VU lamp.

only place in melbourne i could find the 5Mohm pots is http://www.kalex.net.au/ .  they're operating out of a private house in glen waverley.  only $1.50 per item, so i drove over to avoid the $10 delivery.  unfortunately i only got the items i need.  shame i didn't get extras.

neeno - have you biased the unit properly yet?  bias had an impact on output off the unit. . . may explain your difficulties?  your english is fine, and hey - i only speak one language, so you must already rock harder than me!

i haven't been able to get an image to work, so check here for an image : http://home.alphalink.com.au/~mfdu/equipment.html

chris.
Title: All things G1176 - the new "repost" thread.
Post by: Neeno on June 26, 2005, 08:07:16 AM
Hi Chris !
Thanks a lot for your reply !

I've done the calibration procedure 2-3 times, but i always get the same behavior...

Input gain seems too low and output to hot...
IE, if i try to compress a vocal track i have to turn the input at least at 4 o'clock to start seeing gain reduction, and the ouput is too hot, i can't turn the output pot more than at 7 o'clock, because the output seems too high... but if i press the +4 for metering the VU  level is low (around -10, -7 dB)

I have an old freq generator, i scoped the output to get a 1khz signal at 0dB (2.2Vpp, 0.775Vrms), i applied the signal to pin2 and gnd to pin 1 and i've done the bias procedure getting a gain reduction of 1dB on the output.

Is this right ?
Have I to apply the signal to pin 2 and pin 3 ?
Or maybe i have to put pin3 to gnd like in a unbalanced environment ?
Too many questions ? Sorry...

I've checked all the static DC voltages and they are correct (+-0.3V)...

Any suggestion ?

Neeeeeeeeeeeeeno
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 27, 2005, 03:11:13 AM
Quote
Any suggestion ?


- Are you sure you have the "-A" version of the FET?

try changing it to a new one just in case..
Title: All things G1176 - the new "repost" thread.
Post by: Neeno on June 27, 2005, 05:00:36 AM
Hi Gyraf !
I'm using BF245A (Fairchild)
BC107B hfe > 230 (schematic ask for >250 on the gr amp but i've not found 107A so the hfe is a little bit lower)

Can you explain what's the right way to feed the signal into the units for the calibration process ?

I use to connect the gnd from the freq generator to pin1 and the signal to pin2 on the input xlr (do I have to tie the pin3 to gnd ?)

Thank you for your help !

Neeeeeeeeeeeno
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 27, 2005, 05:06:30 AM
Yes, on balanced XLR inputs ALWAYS tie -in (pin3) to ground (pin1) when running unbalanced.

The BF245's can be very different - try with a different one.

Adjust Q-bias so there's only a little drop in output signal level (1dB), with unit in bypass.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Neeno on June 27, 2005, 01:42:16 PM
Ok i'll try...
thank you for your suggestions guys !
Title: Testing Switch Resistance
Post by: heybluez on July 01, 2005, 03:44:13 PM
Howdy Party People,

After a million months I am ready to get back to my 1176. I have it working, at least it sounds like it is BUT my meter does work correctly.  I have it jumping all over the place when I switch it.  I moved to a push button switch so I figured that is the issue.  I am looking through the board for wrong components and I cannot find any.

Question, what is the easiest way to see that the resistors are all ok....?  Meaning when I switch I get the proper amount.  At least this is what i think it is.

Thanks,
Michael
Title: All things G1176 - the new "repost" thread.
Post by: heybluez on July 01, 2005, 10:10:46 PM
would the meter be jumping if i have not calibrated the unit?  I would not think so...but I dont know where to look.

thanks,
Michael
Title: All things G1176 - the new "repost" thread.
Post by: FotisGR on July 08, 2005, 05:17:46 AM
Just a question. Does someone has tried to hear any diference between BF245A vs 2n5457?

I have both of them, so what will be better?
Thank you
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 08, 2005, 06:43:16 AM
No sonic difference that I could detect.

Use the ones that gives you the best tracking between actual GR and GR-meter when adjusted.

Jakob E.
Title: vu probs
Post by: popedh on July 17, 2005, 01:03:51 PM
Hello.
im just finnished an 1176 and have problems with the VU. it works perfect in GRmode, but not in output mode. I dont know if theres a rectifier in my meter. But  should the gr mode work without it?

thanks / Isak
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 17, 2005, 01:25:58 PM
As mentioned several times already, you will need a "real" VU-meter for the 1176 - that is, an AC meter with the right sensitivity: deflect to 0VU when +4dbU is input through a 3K6 resistor.

Jakob E.
Title: VU
Post by: popedh on July 17, 2005, 01:41:47 PM
Yes i know that i need a "real" VU. but this looks like a good one .. and the gr- reduction tracks well.  in outpot mode theres no response at all;(/I
Title: 1176 probs.
Post by: popedh on July 18, 2005, 06:05:42 AM
Hi. i have one more problem... there so low output. everything looks ok and it compress great.. but the output is only about -25db;(
please help me
/Isak
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 18, 2005, 06:44:43 AM
..read this thread and check, check, and double check..
Title: the carbon resistors
Post by: EEMO1 on July 23, 2005, 10:12:18 AM
in mnats bom, why is some of the resistors specifically carbon resistors, 5%? and the two tantalum caps, if electros are ok too? is there a noticable difference in operation?
Title: Amazing
Post by: SeStesso on July 28, 2005, 12:42:54 PM
:thumb: Amazing! It worked at the first shot! I simply powered up the 1176 and it worked without problems at all! Last weekend I went to play with my band so I committed a friend of mine to check the first part of my work: the proper resistences values, caps and diodes polarity. Then I followed mnats advice and went ahead only with the power section first. The tensions were ok. I finished the boards with the rest of transistors and IC's then I made all the wires connections, mostly with shielded cables. I powered up and.. That's all! I started last year a small business named "RealTone" building vintage guitar stomp boxes clones and now I am glad to add this product too to the list. Later, I will fill my studio rack with four 1176 at least! Visit www.studiotriton.com  Text is in italian (I live in Italy) but pics and gearlist are clear enough! Thanks to Mnats and Gyraf and bye bye to all of you.
Title: All things G1176 - the new "repost" thread.
Post by: skrasms on July 29, 2005, 11:09:27 PM
Alright, I've been over the Mnats PC board more times than I can count now, and I just can't find where "R1 - 150ohms" goes. His site says R*1 is an optional 10k, so I thought that wouldn't be the spot for it... unless the 10k is optional in place of the 150ohms. I'm sure this is something really simple, but I'm not seeing it.
Title: All things G1176 - the new "repost" thread.
Post by: mnats on July 30, 2005, 03:42:22 AM
The simple answer is the PCB software I used freaks out if you don't start your component numbering with "1". I used the numbering from the schematic which starts the resistor numbering with "R1A". So it seems that it generated plain old R1 on its own and even gave it a value when it spat out the bill of materials.

Funny that no one noticed until now. It's been updated on the BOM on my site (http://www.geocities.com/m_natsume/1176_bom.html). Thanks for finding the error.
Title: All things G1176 - the new "repost" thread.
Post by: skrasms on July 30, 2005, 06:09:55 PM
Glad to know I'm not just crazy!
Title: All things G1176 - the new "repost" thread.
Post by: SeStesso on August 02, 2005, 08:29:02 PM
Hello. As nicely requested by Mnats, I post a pic of my personal "retro" vision of 1176 limiter.. (http://www.realtoneaudio.com/RealTone%20CLN-1176.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 03, 2005, 01:58:45 AM
Whoa, SeStesso - is that an Altec 1176?  :razz:

Surely looks good!  :thumb:

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: kafuhaus on August 03, 2005, 08:14:35 AM
hi to all! i've searched this board for hours, but didn't exactly get the answers
i hoped to find. first, i've build the 1176 in mnats version with an input transformer. when i measure the the voltages and compare with gyraf's voltages, they match very well. so the board itself should be ok.

when i connect an signal at the input, i get the same signal at the output. also when the unit is switched off. is this normal?

the GR is obviously not in use. the meter does not move and the input gain and output gain pots don't to change anything. i know that i must connect the pot input to *1, but to the remaining pins of the pot still go to pins 2 and 3 on the board??

hope you can help me!!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 03, 2005, 08:19:58 AM
Quote
when i connect an signal at the input, i get the same signal at the output. also when the unit is switched off. is this normal?


Definitely not.

Quote
the GR is obviously not in use. the meter does not move and the input gain and output gain pots don't to change anything. i know that i must connect the pot input to *1, but to the remaining pins of the pot still go to pins 2 and 3 on the board??


Read the schematic and compare with the board - that should make it clear how to wire the unit..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: kafuhaus on August 03, 2005, 08:37:00 AM
thanks very much for the very fast answer!! although i've checked, i maybe missed something.
Title: All things G1176 - the new "repost" thread.
Post by: matta on August 13, 2005, 12:36:24 PM
Hi Guys,

For the 2 BC560's is there an optimal/mini Hfe? I have some 560C's, which read out around the 450+. Will these be okay? The Schemo says that the BC107's in places need to be above 250, but doesn't  mention the BC560's.

Also for the record when a part just has a number and no A,B, or C, what is the Hfe? Is it higer than C or lower than A or equal to C?

Thanks

Matt
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 14, 2005, 06:55:14 AM
Hi Matt,

Any BC560 will do fine here - that's why they're not further specified.

For further info on transistor specs, simply look up the manufacturer data sheets..

Jakob E.
Title: dead torroidal?
Post by: mfdu on August 14, 2005, 07:09:28 AM
i think i killed a torroidal.

i finally got back in and checked big red and old yella.

they've been doing a great job given the limits of only doing 4:1 but it was time to open them back up.  i knew it had to be a fault with C19/C20 the tanty caps.  sure enough, they died when they were back to front and i didnt replace them, then thought there were other problems.   replaced with equiv value electrolytics.

fixed, fired up and tested with 1kHz sine - both came up trumps.

i think i must have bumped the 0V tap onto old yellas board from the torroidal after that.  came out the back of the 3pin header.

blew a fuse.

all system down.

poor old yella powers up and works fine when i plug it in to big red's torroidal.  replaced the 10A IEC inlet and fuse.

do i just call the torroidal dead and replace it at this point?

chris.
Title: All things G1176 - the new "repost" thread.
Post by: matta on August 14, 2005, 09:09:35 AM
Hi Jakob,

Thanks for the advise and tips. Looking at the data sheet and to answer my own question a transistor like the BC560 has a range from 110 ? 800 Hfe, but the A is 110-220, B = 200-450, C =420-800, which makes perfect sense. So in a general circuit if a certain Hfe is not required you would just use a basic transistor, but if you need to 'fix' the Hfe range for any reason you would use the A,B or C varietals.

Cheers

Matt
Title: All of a sudden my G1176 starts to act as a hi pass
Post by: andre tchmil on August 15, 2005, 07:22:09 PM
I have my G1176 working almost every day fo over a year without any complaints until today.
Signals going thru the unit are really sounding kinda Highpassed around 100 hz and have a annoying 5-8 khz boost +/- 3dB.

I have to confess that I replaced the input pot (1Meg ?? ) recently.

Any idea ?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 16, 2005, 04:13:33 AM
Andre,

Look for a balancing issue on cabling. I'm pretty sure that's it.

Jakob E.
Title: Can't Find TLO71
Post by: synthetic on August 31, 2005, 10:32:04 PM
I feel dumb. I've been looking around for a TLO71, but I can't seem to find one. I'm in the USA, so I've tried Mouser, Digikey, Newark and Parts Express. I think I've found something in the TI "TLC071IP," is this right? Mouser's part number is "595-TLC071IP."

(Sorry, is there a parts-ordering meta?)
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 10, 2005, 01:26:35 PM
OK, I found a TLO71 but now I'm having power transformer problems.

When I originally ordered transformers for this project, K&K suggested a Hammond 48V/2x24V transformer. However, I notice in Gyraf's instructions that the center tap needs to be grounded. Is this the wrong transformer? Currently, I have it wired as 2x24V: edge and center go to the main board, and the other two wires are not connected. Does this sound correct?
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on September 10, 2005, 02:50:22 PM
hi synthetic,
have you tried reading this page?

http://www.diyfactory.com/data/transformer_connections.gif

it's found on the meta list which is a great help in most circumstances, just
need to do a little searching.
that being said, your power transformer should have 4 wires for your secondaries.  look on the transformer or any data sheets which came with the transformer to see which ones to connect for your center tap.  the other two will run to the 24V connections (one wire to each ).
hope it helps.
-grant
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 10, 2005, 03:15:41 PM
Right, I have it connected like the "dual isolated secondaries" example. But I'm not reading 24VAC for some reason. I'll keep trying.
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on September 10, 2005, 03:26:52 PM
hi synthetic,
you should have it wired like the split secondaries +/- power supply
example.  with your center tap (0) and the two other secondary leads giving 24V.
-grant
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on September 10, 2005, 03:41:39 PM
hi synthetic,
is this the power tranny you have: model #266J48?
i got this off the hammond site (48V/24V+24V @ 2A)?
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 10, 2005, 06:03:49 PM
Correct, it's a Hammond 266J48. I have Orange and White connected to the AC input, Brown and black connected to the other AC input leg. Blue and red (1/2 of the secondary) go to the two 24VAC inputs of the board, the other two are not connected. No part of the transformer is connected to ground.

OK, I was measuring from one side to ground each time. If I measure from one leg to the other, I read 26VAC. So pilot error again, I guess. No audio yet, so I'll be spending the day troubleshooting.

Thanks for your help, -jl
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on September 10, 2005, 06:57:03 PM
hi synthetic,
looking at the hammond site - the blue and red are on the same winding.
i've only got a couple of diy stuff under my belt so i'm kinda new at this,
but i believe that you should tie the blue and grey wires of the secondaries together (this will be your center tap 0V to the board) and the yellow and red (one each) go to the 24V connections on the board.
your primaries seem to be connected correctly.  just make sure that the AC inlet is grounded via the input XLR 4th lug or chassis.
i tied my center tap connections together and soldered a single lead to it and connected it to my mnats G1176 board.  i believe mnats did it the same way as it looks on his webpage pictures.  my  test points checked out a little under but within voltages.  though i'm using the avel lindberg toroidals.
-grant
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 10, 2005, 07:23:02 PM
I get 26VAC from the secondary when I measure from one side to the other. If I measure from one side to ground, I get 13VAC. I assumed that I only want one half of the transformer secondary wired up, since it's a 48V transformer.

I'm not getting the correct voltage at the input to the regulator. I'm seeing 4.5VDC at pin 1 and 3.2VDC at pin 3. (I think it's pin three: on the other  side of the regulator from pin 1.) I've checked my solder joints and capacitor orientation. I checked the diodes with a continuity tester and they seem to be working correctly. I get -10VDC at R85, which is correct according to mnat's instructions. Any clues as to what might be my problem?

Thanks again, -jl
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 11, 2005, 03:19:38 AM
JL,

As mentioned, you'll need a transformer with at least 2x24V secondary voltage. Otherwise you won't be able to get the needed +30V.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 11, 2005, 11:56:58 AM
I have a 48V/2x24V transformer. I assumed I would only want to use half of this secondary for 24V. Should I be using the entire (48V) secondary and grounding the center?
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 11, 2005, 02:28:37 PM
OK, I get ~30V now, but no audio. I'll troubleshoot some more today.
Title: All things G1176 - the new "repost" thread.
Post by: Mr. Dave on September 11, 2005, 09:07:13 PM
Hi Everybody,
Should the rotary switches on the Mnats boards be shorting or non shorting?
Thanks,
Dave
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 12, 2005, 03:41:41 AM
dosen't matter much - but non-shorting may be preferable by a small margin..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Kristian on September 13, 2005, 05:07:12 AM
Hi
I'm building two 1176 on mnats board. I'm done with the first one but I have some problem.(reversed output Lundahl)
No compression what I can hear. No diffrent sound when I switch bypass and 4+.
Input and output pots are working fine. Sound OK but quiet, maybe 15-20db down.(input and output set at half)

I´ve tried some callibration, but I have chep VU with Ge diode bridge so I have to change 3,6K resistor later on.

I should hear compression? never worked with the real thing, but somethings appers to be wrong.

Kristian
Title: All things G1176 - the new "repost" thread.
Post by: FotisGR on September 13, 2005, 06:13:43 AM
I has exactly the same problem few days ago. Change the 2 fets.  
Must be BF245A or 2n5457.
For VU meters , i used in the past some no cheap but dc vu meters (without diodes for GR metering) that worked excellent for me.

Cheers
fotis
Title: 1176
Post by: thedug on September 14, 2005, 11:28:49 AM
I just got the 1176s up and they are doing some funny stuff.

When the input is all the way up the signal drops out.
The attack doesn?t seem to do anything unless the meter isn?t reflecting it. More investigation may be in order.

One unit stops passing signal when the attack is set to slow.

Also, the output knob doesn't really do anything on that unit.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 14, 2005, 12:14:13 PM
When you turn up input level, GR SHOULD set in heavily at one point. This might be alright.

The attack time goes from fast to damned fast. I'm not sure it would show up on the meters anyway.

But on the second one look for the usual suspects (specially wireing)...

Jakob E.
Title: Checkplot with voltages
Post by: synthetic on September 14, 2005, 11:21:09 PM
I got as far on my 1176 to figure out "it's not working" before I went on the road. I've been sitting in hotel rooms every night wishing I could work on the compressor, then I figured out something I could do. I created an image that labels the expected voltage readings (from Gyraf's annotated 1176 schematic) on top of mnat's checkplot. Perhaps this will be useful for someone -- I'm hoping it will save me time this weekend. PM me if you find any errors and I'll try to keep it accurate.

http://home.earthlink.net/~synthetic/1176_revh_checkplot_volts.gif

Cheers.  :guinness:  :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: Kristian on September 15, 2005, 07:00:05 AM
Quote
No compression what I can hear. No diffrent sound when I switch bypass and 4+.
Input and output pots are working fine. Sound OK but quiet, maybe 15-20db down.(input and output set at half)


I changed FET's but without sucsess. When I pull out Q1 I've got full volume. I guess the gate never opens. Then I saw I had Q15  C=29,6V B=26,4V  E=25,9V. I Changed Q14 and Q15. Checked resistor some resistor around that area but I can't find anything wrong exept the voltage on Q15. If anyone has any ide

Kristian
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on September 15, 2005, 05:48:36 PM
synthetic

that volt plot is a pearler!!!!   good on ya, mate.

i've been meaning to trim through this excessively large post and trim out all the facts and details.  you've inspired me.

chris.
Title: All things G1176 - the new "repost" thread.
Post by: Kristian on September 15, 2005, 07:53:24 PM
Very nice synthetic.
I found my problem. Wrong value on R67(38,3k). Still not working rigth. No voltage drop on Q15 B=16,77 E=16,82 .
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 17, 2005, 08:55:03 PM
I created a second version of the checkplot with voltages. This has the circuit board a little lighter which makes the text more readable.

http://www.jefflaity.com/misc_pix/1176_revh_checkplot_volts.gif

I did another one where I flipped this diagram horizontally, which makes it easier to find test points from the back:

http://www.jefflaity.com/misc_pix/1176_revh_checkplot_volts_rev.gif

I left the old one up at the previous link in case anyone prefers that.

Now, on to my unit. I have it to the point now where it passes audio and seems to compress it, but the input pot doesn't do anything. Voltages look reasonably correct overall, and I don't see any obvious solder bridges. I can measure the change from 10k to 0 with my meter as I turn the knob.

Now, I have the entire board stuffed: both transformer and op amp inputs. I planned to listen to both and choose one, or possibly add a switch. I added a jumper from pad 1 in the middle of the board to pad 1 of the input pot for the transformer balanced section. I tried desoldering this jumper but this doesn't help. I get no input from the transformer balanced section. Audio passes from the op amp section, only with the input knob doing nothing.

Again, this is using the mnats board (which is now famously featured on analogindustries.com). Let me know if you have any guesses. Thanks, -jl
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 18, 2005, 02:05:18 AM
If I measure the input pot connections on the board, I can see the resistance change as I turn it. If I disconnect the pot, the signal goes away. If I short connections 1 and 2 together, it acts the same as if the input pot is connected. Any clues? Thanks.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 18, 2005, 02:10:24 PM
Synth,

Great voltage plot, that one!!!

The input pot forms a simple voltage divider to ground. Shouldn't be hard to trace signal through.

Make sure that you have ground at one end (ccw), signal in at the other (cw), and take out signal to the compressor section from the centre thingy, the viper...

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 18, 2005, 08:09:04 PM
It took me a minute to figure out that viper=wiper. I'm not making a joke about your excellent English, it just took me a while to figure out. :grin:

OK, the input pot problem is solved, it was a broken pad on pin 3 of the input. I had another broken pad on the board: there was no contact between the pad and the trace next to it, so I had to scrape off a little bit of plastic and make a solder bridge. Just a note for people troubleshooting the otherwise excellent mnats board. :guinness:  :guinness:

Now I have it mostly functional, but there are two problems. First, I can't get the GR meter to reach 0dB. It hovers around -14dB at the max, and none of the adjustments make much of a difference. The VU meter is working fine, although I had to add a rectifier circuit to the meter to get a good signal level. The gain reduction meter is low with or without this rectifier in the circuit.

The second problem is that there's a fair bit of distortion as I increase the compression. I can't align the Q Bias either, so I'm assuming this is all related. I've been trying to find answers in the repost, but it's tough to search for this type of problem.

Thanks again for your help.
Title: All things G1176 - the new "repost" thread.
Post by: spacecho on September 18, 2005, 11:31:52 PM
Hi all,

i have finished my board and i have a few questions?

i noticed that there is a voltage difference of 46! volts between the hot and earth connectors of the audio output. this cant be right?

has anybody had this occur?? is it normal???

it is there regardless of the volume settings.

i searched the forum and found the wonderful voltage diagram but there is no measurement reading of the audio in or out.

Apart from this, the unit sounds and works fine???

also, the meter dosen't work in VU mode - it is a cheap meter without rectification - maybe a ge diode bridge will fix this??

i guess i should find the cause of the 46v before i use it again - or unless this is normal???


thanks all!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 19, 2005, 04:13:14 AM
Synth,

Seems likely that you have the wrong FET's? BF245 Atype?

spacecho,

Output is transformer-balanced, so there's nothing between 0 and hot/cold. The other questions have been answered before.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: spacecho on September 19, 2005, 06:17:33 AM
Yeah, im using the bf425A as listed on the mnats site.

i knew that the voltage thing was bad, will start checking for problems, it's funny that it works fine though.

i have begun re-reaqing the thread to find out about the meter, i have some true vu / ppm dual meters in a high end tape deck that i could connect to compare as well.

will post pics when it is all good.

thanks Jakob.
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 19, 2005, 08:06:15 AM
No, I have BF-245A. Mouser part# 512-BF245A.
Title: my 1176
Post by: EEMO1 on September 21, 2005, 08:16:10 AM
hey,


 i got my baby done. still need the light for the meter. damn this compressor sounds sweet. the volume is pretty LOUD, the characteristics is awesome!

 i used oep output transformer and ic thing on the input. i fried a couple of regulators in the process but i managed to get it working. the calibration was a bit over my head but i guess i pulled it off, because this thing works great!

 thought i'd share. thanks groupdiy.

-eero
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 21, 2005, 08:01:16 PM
So, should I be replacing my BF245A? Does it sound like my FETs have given up the ghost?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 22, 2005, 02:56:19 AM
Yes, try with different ones - the ones you have may be fine, but just out of specs.
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 24, 2005, 07:26:57 PM
I replaced both BF245As and the trimpot, but no luck. Any other ideas?
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 25, 2005, 06:11:14 PM
I measured voltages against the plot again, and the TL071 is only getting -8.3V, not -10V as the schematic says I should be seeing. Is this a symptom or a side-effect? All of the other voltages are within 0.5V as far as I can tell.

To review, the VU meter mode works, but not the GR meter mode. When I switch the unit on in GR mode, the meter starts at around -15, drops to 0, pegs, then rests around -15. I can adjust the meter track trim (R54) to change this +/-3 dB or so. When I try to set the Q bias, turning that control has no effect. The VU zero trim doesn't seem to do much, either. The compressed audio seems distorted, probably because I can't set the bias.

Thanks in advance for any ideas you might have.
Title: All things G1176 - the new "repost" thread.
Post by: spacecho on September 26, 2005, 07:43:14 AM
hi everybody,

just finished my 2nd 1176, glad that they both work! 1st time

i noticed that my voltages are all identical to the checkplot except that my voltage reading on the voltage regulator leg reads 30v instead of 35v - could this be because i used a 1.1k resistor for r87 as in the schematic - i have heard of many using a 1k or 1k2 resistor instead as these are readily available. (i just put 1k + 100r in series)

excuse my ignorance but i noticed that both inputs have 14v on the hot and cold signal points. Is this normal?

(as for my unit reading 45v on the output - last post - that has suddenly vanished? i might have imagined this - 6 hours of inhailing solder!

truly great project!

i might change direction and build some guitar effects now - mutron 3 and univibe anyone? - check out this link? www.generalguitargadgets.com

thanks again Jakob and Mako.
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on September 28, 2005, 02:13:24 PM
Bump.

Help me, Gyraf Kenobi. You're my only hope.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 29, 2005, 02:48:08 AM
:grin:

Sorry, Synthethic - I'm out of ideas...

Try checking again for component values, orientation, soldering, wireing, and shorts - it's nearly always these problems when it comes to it. And then try tracing the signal through the sidechain - it could look like you have excess DC leaking through to the fet's (hopefully you did NOT replace the FD333 ultra-low-leakage diodes with something else)

spacecho,

I think there's something wrong with the way you measure - or maybe your voltmeter. Check it's batteries  :razz:  this is a known problem..


Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Esset on September 29, 2005, 02:59:00 AM
Hello guys!

I?m building a dual G1176 on mnats rev H-boards and one is completely dead (going to switch the transistors and FET?s on that on because I?ve think I?ve burnt them all in a little shortage-story).

The other one, passes audio, all pots, the meter and switches work, but the audio is heavily distorted and no bass-frequencies.

My PSU voltages are: +30.1 and ?7.8 on the following points (these are the same on the burnt board):
http://www.geocities.com/m_natsume/images/1176_-10_small.jpg
http://www.geocities.com/m_natsume/images/1176_30V_small.jpg

Checked the voltages over the transistors, and some are a bit off but not much though.

E | B | C
Q2- 0,52 |  0,85 | 1,77
Q3- 1,16 | 1,77 | 12,14
Q4- 11,74 | 12,15 | 30,1
Q5- 4,4 | 4,22 | 28,2
Q6- 29,0 | 28,2 | 14,35
Q7- 29,6 | 29,0 | 14,4
Q8- 13,8 | 14,4 | 30,1
Q9- 13,7 | 13,3 | 0,004
Q12- 5,05 | 5,64 | 17,98
Q13- 17,73 | 18,08 | 30,1
Q14- 2,4 | 2,4 | 26,5
Q15- 26,5 | 27,1 | 30,1

Could it be that the audio-signal into the board is to hot? That would explain the distortion but not the lack of bass-frequencies. But I doubt that since the meter doesn?t overload.

Any idea´s? And if any please put them in ?stupied-mans-terms? though this is my first project with not much electrical-skills to start with, I?m learning as I go.

Regards
Stefan

EDIT: Using Lundahl output transformer and IC-based input
Title: All things G1176 - the new "repost" thread.
Post by: spacecho on September 29, 2005, 03:30:25 AM
hi stefan,

my unit definently distorts if the input gain is set to high - this unit seems to have heaps of gain so i usually have it set at 3-5 for a signal around 0db

as for the lack of bass response - is it possible that you have wired the input or output out of phase? - the connectors for these on the board are mirrored (ie. opposite) -/+ and +/- ?

hi jakob - i dunno - maybe i am doing something fundamentally wrong but i checked the input voltage by putting the black lead to the earth point and the red lead to either the hot or cold - it gave me a reading of 14v when the meter was set to DC <20v range.

the thing works and sounds good - hasn't blown up yet, i might get to the bottom of it when i pull the unit out to finish calibrating it - borrowing a scope.
Title: All things G1176 - the new "repost" thread.
Post by: Esset on September 29, 2005, 04:11:18 AM
Quote from: "spacecho"
as for the lack of bass response - is it possible that you have wired the input or output out of phase? - the connectors for these on the board are mirrored (ie. opposite) -/+ and +/- ?


I'll take a closer look at that this weekend when I have some time over.

The distortion however is there the whole time, even with input and output gain as low as  possible (pots fully CCW)

Wrong resistorvalue somewhere in the inputstage maybe?
Title: All things G1176 - the new "repost" thread.
Post by: FotisGR on September 29, 2005, 07:07:18 AM
ATTENTION please.
Yesterday i finished a 1176 for a friend of mine but it didn't worked at once. All was OK  but no gain reduction at all at 4:1 and 8:1 potition. On 12:1 and 20:1 switch potition it has enough gain reduction . I spent a couple of hours doublechecking the circuit and i found this problem.
Impossible for me , but real.
The ratio switch (like Lorlin type 2 contacts 6 potitions) it has WRONG contacts.  Turning it full ccw for 4:1 the contacts are A,5 and C,11 instead A,1 and C,7.
I don't know if there are different switch types. I have 6 pieces like this, but this is the only exception.

Cheers
Fotis
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 29, 2005, 07:50:58 AM
Have you tried taking the locking nut out, turning the switch completely countercloclwize, and reinserting the pin?

If the switch is set to a position higher than the programming - at the time of programming - then the switch gets caught on the "wrong" side of the end-stop, with unpredictable results..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: FotisGR on September 29, 2005, 08:49:05 AM
You are right Jakob. :thumb:
 The swithc was looking like 2 cont. 8 potitions. I fixed it 100%..
for a couple of minutes i was thinking that it is a bad dream... :grin:

Cheers
fotis
Title: All things G1176 - the new "repost" thread.
Post by: Esset on September 30, 2005, 03:09:46 AM
Quote from: "Esset"

The other one, passes audio, all pots, the meter and switches work, but the audio is heavily distorted and no bass-frequencies.

...

EDIT: Using Lundahl output transformer and IC-based input


Any ideas or thoughts about the distortion? It distorts even with all pots fully CCW (and CW if the pots where to be faulty connected)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 30, 2005, 03:40:13 AM
Esset,

Check the complete signal path again. Trace the signal through the unit to find out where it's going wrong. I think we have a signal-tracing question somewhere earlier.

As you will see if you read this whole thread, nearly all errors are

- Wrong components
- Wrong orientation of components
- Solder bridges shorting on pcb
- Bad wireing
- Bad soldering/left-out solder points

..in more or less that order..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: thedug on October 05, 2005, 10:47:15 PM
I'm getting distortion on my 1176.

I am running a 1k tone through it and when the signal hits about -6dB on the console I start to hear distortion. This is happening even in bypass mode.

I did the transformer mod.
Title: All things G1176 - the new "repost" thread.
Post by: matta on October 24, 2005, 03:35:17 AM
Hey Guys,

Does anyone know if I can power up my G1176 without a meter just to check it
passes audio and compresses?

I know that I won?t be able to set the bias without the meter, I?m just
stuck for money now and will only be able to get the meter in December. Do I
need to wait to have the meter before trying the unit out if I have built
the rest of the unit?

Also I noticed in another post that someone mentioned you don?t need the
mu-metal case for the OEP for Mnats boards, anyone tried this? If I can
loose it it would save a few bucks.

Thanks

Matt
Title: All things G1176 - the new "repost" thread.
Post by: FotisGR on October 24, 2005, 03:46:08 AM
You don't need it for now. You can easily set bias using a software metering. Giving a signal input like Jakob say and just set bias for 1db drop down out on your sound card's meters. Also for reading gain reduction you can use every vu that you want . I always use dc vu meters ( without diodes ) . They work absolutely perfect, exept vu reading. If you want vu reading use sifam or dc vu with diodes etc.

Cheers
fotis
Title: trafo out mod
Post by: keithcamilleri on October 25, 2005, 08:32:45 PM
hi guys,

wanted to ask a quick question i've done the mod for the trafo out to be 1:2.

The unit was already calibrated, do I need to calibrate the unit again after the trafo mod?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 26, 2005, 03:06:20 AM
Nope, calibration stays the same when changing output transformer ratios..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: anneflyr on November 03, 2005, 07:38:42 PM
Hello.

I've had a lot of fun doing this project. It is all together now. Signal is running trough, and input pot and output pot is working. the problem is that it is not compressing.... :?

I don't have a meter jet, but it should compress without it, should it not?

I have done a lot of testing. All my values seem to be correct. It's spot on or +-1 volt on all measure points. I've read trough all post concerning this project, but I could not find help. I found this answer on another unit that didn't compress.


Quote
First of all - does point21 change with signal level?

There is a "threshold" - the negative voltage at point21 - that has to be overcome by input signal level before the FD333 diodes starts to conduct.

Input a loud signal, input at max, and measure changing DC voltage at point21. When this voltage is some +0.6V higher than the DC voltage at point19 (which is set by Q-bias), the diodes conduct, and gain-reduction sets in. Start out with trying different settings for your Q-bias, just in case it is at one extreme.

Does meter and gain change with Q-bias adjustment? This verifies that the FET's and the release circuit is working.

Jakob E.


I have tested point21. It does not change with input; it does change when I regulate the Q bias.
Turning the Q bias, the gain changes slightly when the release is full clockwise, and I have the same slightly change when I turn the release pot.

I've been trough the schematics many times, been lifting out resistors, looking closely on the caps and on the soldering to be absolutely sure everything is correct. I just cannot find any errors.

Does anybody have an idea where to look further?

Andreas
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 04, 2005, 04:44:00 AM
Andreas,

Check thet the FD333-diodes are mounted the right way around. Check signal levels (AC and DC) before and after these diodes - it is here that the audio signal AC is converted into DC for the fet control..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Svart on November 04, 2005, 08:29:27 AM
i've been using my dual mono 1176 for a while and it is wonderful!  one problem is that I used a dual VU meter and it barely moves.  set to VU mode it moves a small amount and under much higher levels it moves more.. it's obvious that I need to adjust the drive to the meter..

so my question is:  how do you figure out how much drive you need from measurements taken from the meter and how would you make sure that it is indeed correct?

yes i know this is not much information..
Title: it's doing what it was made for....
Post by: anneflyr on November 04, 2005, 04:48:37 PM
It is compressing :grin:

First I have to say. There are two really educating periods during a project. Part sourcing and error tracking. Specially the last really makes you go through the unit you're building teaching your self how it works.

I checked around the fdh333, and also the whole signal path. Suddenly out of nothing it was compressing. My guess it faulty wiring, I resoldered all the wires paying special notice to point 7, 19, 20. It is working!! It is always something stupid, is it not.

You are a angel Jacob to answer all this questions about your projects.

Don't know if you remember, I offered you some Tore Seem schematics some months ago. I'm sorry, but I only have block diagrams, no in depth schematics. Trying to get hold of some, if I get them you'll be the first to know.

Thanks for a superb compressor, now calrec is next.  :green:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 06, 2005, 04:46:54 AM
:thumb:
Title: All things G1176 - the new "repost" thread.
Post by: bradb on November 07, 2005, 10:43:55 PM
I've got the optional input transformer and I'm finding that there isn't a single location for info on how to wire this thing.  I've got the mnats board.  his instructions on his website are regarding different ratio/meter boards.

Some questions, confirmations:

R* and R*1, these 10kohm resistors need to be added when I use the optional transformer, correct?

BUT, if I add these resistors, I can't mount the Lundahl flush to the PCB.

Do C* and C*1 need to be added as well?  what are these values?

With the optional input tranny, Input pin 1 needs to be run to 1* next to point 22?

Just want to also confirm that pin 4 on the meter board goes to pin 4 on the ratio board.

Thanks all!

Brad
Title: All things G1176 - the new "repost" thread.
Post by: bradb on November 08, 2005, 11:01:26 PM
Thank you!,

Just to confirm:
C* is 1000uF/35V
C*1 is 100uF
C*2 is 0.1uF
C*3 is 0.1uF

I think I'm on track.  I am following some of Mnats advice in using shielded cable to wire certain points and grounding at one end.
Title: release (me) pot!
Post by: mikeyB on November 13, 2005, 12:50:06 PM
Now that electrovalue got bought out and then the stock up in smoke!! grrr!!! - does anyone know where to get 4M7 and other high value pots - all i can find are presets and my eyes are beginning to bleed! I'm UK based - by the way!
Title: All things G1176 - the new "repost" thread.
Post by: louder on November 13, 2005, 02:00:02 PM
alo mikey
think digikey carries 5M pots.
best regards
pedro
Title: All things G1176 - the new "repost" thread.
Post by: Svart on November 17, 2005, 08:07:29 AM
Hey, sorry to repost this but i'm still wondering about it:

i've been using my dual mono 1176 for a while and it is wonderful! one problem is that I used a dual VU meter and it barely moves. set to VU mode it moves a small amount and under much higher levels it moves more.. it's obvious that I need to adjust the drive to the meter..

so my question is: how do you figure out how much drive you need from measurements taken from the meter and how would you make sure that it is indeed correct?
Title: All things G1176 - the new "repost" thread.
Post by: Greg on November 17, 2005, 08:51:24 AM
Did you do the calibration procedure on Gyraf's site?
Title: All things G1176 - the new "repost" thread.
Post by: Luny Tune on November 20, 2005, 02:39:56 PM
Hi all,

I'm building my first G1176 and at the same time I'm making a complete shopping list for all parts in Denmark. (Some of the webshops do ship internationally so I'll publish the list here too of course.)

Now, I've come to the same stop a lot of others have. I can't find the BD517 anywhere. I have seen that BD517/518 can be replaced by BD135/136 and that you just have to bend their legs to fit them correctly into the PCB as they're not directly compatible. It's not too hard really.

I've read many pages and comments but I have two questions still.

The first one is of general interest I think. Is there any audible difference at all between the BD517/518 and BD135/136 combinations?

The second question arises because I have already soldered in the BD518 I found, and I didn't know it would be a problem to find the other one. Can I solder in a BD135 as a substitute for the BD517 and just leave the BD518 in, or well I have to replace the BD518 with a BD136 as well?

I found the question about the sonic difference asked before, but I couldn't find an answer.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 21, 2005, 04:17:05 AM
There will probably be very little sonic difference between the two types, but I haven't A/B'ed them. Use BD135/136 or BD517/518 pair-wise, don't mix. You want decent complimentary action..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Luny Tune on November 21, 2005, 07:38:28 AM
Thanks, Jakob.:thumb:
Title: All things G1176 - the new "repost" thread.
Post by: mnats on November 29, 2005, 02:55:21 PM
Did the distortion trim on my dualie last night using a Sound Technology 1700B. Gotta love all those interlocking pushbuttons.
(http://img.photobucket.com/albums/v295/mnats/dual_1176_dist_trim.jpg)
We were able to get the right channel down to 0.08% and the left channel to 0.075% THD. Could be wrong, but I think I read somewhere that if you don't do the trim you should leave the trim pot at the midpoint. Well, with the distortion trimmer turned to nearly the 0 ohm point (clockwise on the G1176 boards) the distortion was lowest; turning it all the way gave only a modest rise in distortion - around 0.1%. At the midpoint distortion was about 0.5%.

Anyone else done the distortion trim? Would be good to compare notes.
Title: All things G1176 - the new "repost" thread.
Post by: romeojesus on November 29, 2005, 04:17:02 PM
> one problem is that I used a dual VU meter and it barely moves. set to VU mode it moves a small amount and under much higher levels it moves more..

i have built mine with a sifam meter...my meter does not
move much in vu mode either..(I did the calibration thing)...
in gain reduction mode it works as it should ...

(used the original gyraf board)
Title: All things G1176 - the new "repost" thread.
Post by: Luny Tune on December 04, 2005, 12:00:49 PM
I have finished all solder work on my first G1176.
I haven't gotten the chassis nor the frontplate for it yet. They should arrive soon.

I'm trying out an alternative meter so note that there could be "something" there.

I have checked and doublechecked for all the usual stuff, component values and orientation, solder blobs, breaks, and that all pots and switches are connected correctly.

I have then powered up and checked that I'm getting the right readings as written on the PCB and the diagram. (Not the more extensive one that Jakob made with readings all over the place. I'm thinking that the rough overview would be sufficient to begin with.)

Then I've connected it to the patchbay, eager to hear the unit in action, but:

1. There is no sound through.

2. The meter acts weird. I noticed this when I first powered up of course. It's a VU meter but first and foremost it acts like it should be connected + to - and - to +. When I switch to GR the needle is glued to the left side of the window while in Bypass and VU mode it returns to the same position as when I turn off the unit.
I've tried to switch polarity on the meter and that gives the expected reaction although it needs serious adjustment somehow. In Bypass and VU mode the needle still sits correctly and in GR mode it now rests at appr. -15 dB (or something. I mainly just focused on the needle moving towards 0dB now).
Note: Regardless of the polarity, in VU mode the needle is "dancing" a little erratic dance. Not very much movement but just enough to look like it's reacting to an outgoing signal, but it doesen't matter whether there's an input or not.

3. How critical is the meter for operating the unit? Will it affect sound at all if it's broken or as in this case (maybe) not the right kind?

I've read the "G1176 : No smoke but then no signal..." thread and will error trace following those directions but I would like to hear if anyone can spot anything with the above description? For instance if it's impossible to make it work if it's not in a case? I mean, the missing common chassis...or something...

Thank you!
Title: All things G1176 - the new "repost" thread.
Post by: synthetic on December 04, 2005, 02:51:31 PM
My G1176 is finally working. Big thanks to nwsoundman for taking the time to have a look at it. For the archives: the problem was that I couldn't set the Bias trim and the GR meter stopped at about -16dB. I replaced the BD518s and that didn't fix the problem. He finally figured out that there are TWO jumper holes marked "18," you use the one depending on the size of your trim pot. One he switched to the other hole (and replaced a blown TL071) the unit started working correctly.

Thanks again to nwsoundman, mnats, Gyraf and everyone else who made this compressor possible. I'll be posting photos soon.

 :guinness:  :guinness:  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: louder on December 04, 2005, 05:07:49 PM
alo
just found something strange.
in the bom,s1 says:2 pole-6 positions.
in the small board,it says:2 pole-4 position.
which one it`s correct?.
best regards
pedro
Title: All things G1176 - the new "repost" thread.
Post by: bradb on December 09, 2005, 12:19:41 PM
using relays lets you bypass the line amp inside the 1176... so that may or may not be something you want to do.

my experience is that I usually have all my comps on GR mode, rarely use the VU mode.  

depending on your input and output level, your VU meter will dance around madly with signal.  depends on whether you think this is useful.

one thing however is I set it to VU mode for the ALL switch, so as to not hold the meter pegged...
Title: Too hot output
Post by: Ozzie on December 11, 2005, 09:28:12 AM
I'm building two 1176's using Mnat's boards and with the OEP transformer on the output only. I finished wiring one and it's passing audio, but when trying to calibrate it, I get a very hot output:

- I'm inputting a 250Hz sine wave at 600mV (tried with a lower voltage too), connected to pin 1 and 2 on the xlr (pin 3 not connected)
- Starting with R81 fully CW, I back it off until I get a 1dB drop in output level with my external meter.
- After this calibration, still in bypass, with the input pot on 8 o'clock and the output pot on 2 o'clock, I get 944mV on the output xlr (pin 1 and 3 tied together)

The unit seems to be working and it's compressing, but the output seems to be way too hot.

However, I just spotted that the supplier sent me some BC108B's instead of BC107B's, so Q3 and Q15 are BC108B and the others BC107B (will change them as soon as I get some new ones). Could this be causing the hot output?
The other trasnistors used are:
Q1, Q10: BF245A
Q6, Q7: BC560C
Q8: BD135
Q9: BD136

/Oscar
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on December 11, 2005, 11:02:03 AM
Quote
but the output seems to be way too hot.


There is a lot of gain in the 1176... How do you judge that there's too much?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Ozzie on December 11, 2005, 04:53:56 PM
Jakob:
Quote
How do you judge that there's too much?


Actually, I haven't tried it in my studio yet, just with an unbalanced hook up at home (test cd and computer), and it's been years since I used an 1176. But, I figured setting both input and output at unity gain (which normally is about 2 o'clock, right) would output the signal at the same level as it was input (in bypass that is). If the levels are ok as they are, then nobody's happier than me ;)  

Still wondering what the BC108B's would do to the signal though.

Thanks

/Oscar
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on December 12, 2005, 05:53:20 AM
I think unity gain is much below 2O'clock - but I don't have a unit around to verify that..

Check for yourself the data sheets for differences between 107's and 108's..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: pmroz on December 31, 2005, 09:54:24 PM
.
Hi all,
Finally finished all the G1176 links, websites etc. Thanks to all who contributed.
Orson for saving the old bits, all who gave calibration info, pioneer trace-cutters, etc..

Haven't started project yet, a few questions:

1. Output transformer: Has anyone used an OT different than OEP or Lundahl? Didn't see any.
Trying to figure pri/sec impedances for alternate trafo spec.
On G1176 schem, with both windings in series:
Lundahl 1540 = 1.22K:1.6K   ;  OEP  262A2E  =  600:2.4K
1K R terminates secondary on G1176 schem.
Also a bit in my notes saying "any 1:1 will work" but didn't footnote it or list author.  
Will a 600:600 work for this? (have Triad HS-56V and some other 600:600).

2. Input transformer : From Jakob's site:
The transformer input is an option.
If using the input transformer, ONLY connect point*1 to the input level pot, as the point1 is only for electronically balanced inputs. Actually you could leave the 5532 out, but if it's already there, dont bother to remove it. If using the input transformer, remember to use the inputs marked "Optional trafo input" and not "BAL. INPUT"


So wondering if it's possible to mount all the parts + input trafo, and have separate input jack available for each. Would it be as simple as a switch or relay before the input level pot, switching between point1 and point*1? Can't tell from Jakob's schem. Anyone tried?

3. Planning to try O-12 and others on input, like soundguy posted somewhere, then ran across this in Orson's notes:
Duka:  I wanna build G1176 but with 0-12. Can I use this circuit with pot like with Lundahl use or I must use dual pot for "T" atenuator like on original schematics.
No answer in the notes. Missed any other reference to a T-attenuator. I'm assuming a pot is fine, T-atten not needed so long as trafo leads go in the right holes. Correct?

Thanks, Paul
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 02, 2006, 05:11:21 AM
1) Dunno

2) Yes

3) Dunno
Title: All things G1176 - the new "repost" thread.
Post by: pmroz on January 02, 2006, 12:30:50 PM
.
Thanks Jakob.
And happy New Year.
Title: Gssl sidechain on G1176? Good, cheap 19" chassis in UK?
Post by: mikeyB on January 09, 2006, 11:44:23 AM
Has anybody tried Gssl sidechain filter on the 1176?
Another general question - where do you get good, cheap 19" chassis in UK?
Title: All things G1176 - the new "repost" thread.
Post by: rove on January 31, 2006, 12:45:09 PM
just finished reading mnats rotary switch page (thanks!) and I wondered if anybody had a (mouser/digikey) part number for those pins and crimps that he uses to attach the wires to the boards.  I may just go ahead and wire directly, but it seems like a nice touch...
Also, what type of switch would be needed and where in the circuit would it go (referring to above post re: switching between xformer and xformerless in put)?
thanks
Title: All things G1176 - the new "repost" thread.
Post by: mnats on January 31, 2006, 02:45:09 PM
Quote
just finished reading mnats rotary switch page (thanks!) and I wondered if anybody had a (mouser/digikey) part number for those pins and crimps that he uses to attach the wires to the boards.  I may just go ahead and wire directly, but it seems like a nice touch...

Take a look at the Mill-Max PC Receptacles and PC Pins page in the Mouser catalog. I've bought them from a couple of different sources here but if you go to www.jaycar.com.au and do a search for HP1260 and HP1252 you can get a better idea of what you're looking for...
Quote
Also, what type of switch would be needed and where in the circuit would it go (referring to above post re: switching between xformer and xformerless in put)?

If you are just going to switch between the output of the transformer and electronically balanced input circuits, you just need a DPDT switch. I guess the plan above was to tie the input transformer and IC input together and run them in parallel to the input jack?
Title: All things G1176 - the new "repost" thread.
Post by: pmroz on January 31, 2006, 06:44:43 PM
.
Quote
I guess the plan above was to tie the input transformer and IC input together and run them in parallel to the input jack?

Nothing real slick. The 2 separate trafo/trafoless inputs to their normal headers, then 1 and *1 to each side of a switch, center of switch to level pot. SPDT would work I think.

It's just to quickly A/B different configs before settling on one, see how it sounds nicest...

I'd guess to use both inputs permanently/practically, calibrating the meter to be worth anything would require matching gain between outputs of trafo/trafoless gain stages, at the pot... so find the trafo you like, then adjust gain-set R of 5532 to 'match'? Overkill for me, and possibly beyond me skills, so will probably just use the one nicest option for the final box.
Also there's couple threads around about  T-attenuators, 2:1 step-down function on original 1176 input trafo, etc. Could get complicated with sub trafos.

Love Jakob and Gustav's group-build pics... stacks of snacks.

Paul
Title: All things G1176 - the new "repost" thread.
Post by: Mbira on January 31, 2006, 06:46:33 PM
Is the 50 mV used to do the calibration RMS or P2P?

Thanks.
Joel
Title: All things G1176 - the new "repost" thread.
Post by: mnats on February 01, 2006, 01:58:03 AM
Quote
Nothing real slick. The 2 separate trafo/trafoless inputs to their normal headers, then 1 and *1 to each side of a switch, center of switch to level pot. SPDT would work I think.

It's just to quickly A/B different configs before settling on one, see how it sounds nicest...

Duh. Yeah, SPDT - should know better than to answer posts before that first cup of coffee.

OK, so you're going to use seperate input jacks? I was going to mention that it probably isn't optimum to tie the IC input permanently to the input transfomer primary.
Quote
Has anyone used an OT different than OEP or Lundahl? Didn't see any.

Is Kubi around? I think he's been trying out different transformers.
Quote
just finished reading mnats rotary switch page (thanks!)

Cool - maybe others can take a look to see if I made any more stupid mistakes: http://www.geocities.com/m_natsume/1176-wiring-rotary.html
Title: All things G1176 - the new "repost" thread.
Post by: Mbira on February 01, 2006, 12:29:29 PM
I moved this to the "calibration thread so it will be easier for people to find this info next time...
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 01, 2006, 12:33:27 PM
I really don't think it matters... But as rule-of-thumb, ALL ac voltages you see mentioned are RMS unless otherwise specified..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Mbira on February 01, 2006, 12:34:26 PM
saw your reply after I moved things...Thanks Jakob...
Title: All things G1176 - the new "repost" thread.
Post by: Ted on February 07, 2006, 08:08:43 AM
I've some problems with my 1176 clone.
I start with building the power supply only; everything was right +30v and -10 where fine.
When I stuffed my board and checked powered up the second time. I felt the 7824 where too warm.
Isolated only the output pin from the 7824 I measure 24v. But in the circuit it came out 3volts? -10v is okay
I checked the board several times on bloops but I can't find anything.
Somebody any idea where to start?

Thanks for reading!

Ted
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 07, 2006, 08:41:58 AM
Ted,

Try with a small heatsink for the 7824. It'll shut down if it gets too hot..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Ted on February 07, 2006, 08:58:22 AM
I've used a small heatsink. And one 7824 is already "burned" out.

ted
Title: All things G1176 - the new "repost" thread.
Post by: Ted on February 07, 2006, 10:44:47 AM
I fixed it. Changed the 135 and the 136.



 :cool:

Ted
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 08, 2006, 04:02:41 AM
:thumb:
Title: Oscillation
Post by: thedug on March 01, 2006, 12:57:04 AM
I found an oscillation in the 2 1176s that I built..

I put the cap in parallel with the 1.2K resistor that hangs off of pin 6 of the NE5532.
39pF and 12pF are the values I used.  Both eliminated the osc. completely.

Approx 700 kHz, 0.5Vp-p measured at pin 6 of the 5532.

Thoughts?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 01, 2006, 03:19:45 AM
I never had that...?
Title: All things G1176 - the new "repost" thread.
Post by: imo on March 01, 2006, 04:03:39 AM
i had a question on the 135 and 136. WIth my challenged schematic skills, it seems that you still need to twist the pins to get them to fit correctly on the rev 7 gyraf design. the schematic seems to back this up. I ask as i thought in trolling through the forums that this wasn't necesary in the latest revision. I think i hit an information overload, and could use a clearer and wiser mind backing this up.
i give thanks
Ian.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 01, 2006, 04:15:33 AM
Yes, you need to twist the legs when using BD135/136 output transistors - the latest PCB is still made for BD518/519 (as printed on the component side).

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: thedug on March 01, 2006, 08:38:26 AM
Any ideas what that could be?
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on March 01, 2006, 10:21:12 AM
Hi
I am finishing my Dual G1176. After assembling I put signal without fet's and everything is OK. If Input and output pots are on about 12.00 it is like signal with true bypass.
Problem is:
When I put BF245A I lost signal. Zero on G.R position on meter I can adjust!
What to do?
I check all voltages and its OK.
Thanks
Duka
Title: All things G1176 - the new "repost" thread.
Post by: thedug on March 01, 2006, 12:20:10 PM
Should I be worried about this extra cap for the oscillation effecting the sonics?

Did I do the right thing? Should I look into other things? I.E. Could this indictate another problem?
Title: All things G1176 - the new "repost" thread.
Post by: Lowfreq on March 01, 2006, 08:58:12 PM
Hey everyone,

As one might guess I'm havin a few problems with my G1176.
I'm using mnats version with an OEP a262a2e transformer.

Anyway, the prob i'm having is that altough the compressor works and is compressing well it seems strangley slow sometimes. For example if i consatntly sang/talked/rapped etc the compressor is happy and works well. However if I stop for anything more than a second, to take a breath etc, it takes a short time for the comp to respond to the first burst of my voice again. I tried this with an extreme setting 20:1 etc, fast attack blah blah, and the note the comp dosen't catch always distorts and peaks the meter.

I've been through the whole bias procedure and the Gain zero/trck parts went sweet, but nothing happened at all witht the Q-bias part, which i thought would be very important.
Checked for shorts etc, no luck....................I'm a bit confused

I've read and searched a bit through this thread, but 53 pages is a lot to wade through while getting ready for a tracking session tonight.
Any ideas or expeirence with this one anyone?

regards

Steve
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on March 02, 2006, 01:50:42 AM
Quote from: "dukasound"
Hi
I am finishing my Dual G1176. After assembling I put signal without fet's and everything is OK. If Input and output pots are on about 12.00 it is like signal with true bypass.
Problem is:
When I put BF245A I lost signal. Zero on G.R position on meter I can adjust!
What to do?
I check all voltages and its OK.
Thanks
Duka

I solved!!!
Wire from point 7 from main board to pin 7 on ratio switch board didnt soldered (on both channel) :oops:
Because I add stereo interconection and switch for compresor I made mistake.
Now to match fet :?
Duka
Title: All things G1176 - the new "repost" thread.
Post by: Brizco on March 03, 2006, 09:17:47 AM
Hello!

have a similar problem with my gyraf 1176 like some others before:

signal passes thru, without hum. input and output potentiometer are working.
but: i cant hear any compression. (vu meter is not working too, but doesnt matter now).

i havent calibrated yet.
i only have 0.7 volt on the 10v rail. (by the zener)
i checked for shorts, values and soldering...
all diodes are soldered the right way.
i got 10v on R85.

i dont know what more to do... or where to search...
so i be thankful for some solution inputs! thank you!!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 03, 2006, 10:12:55 AM
Quote
i only have 0.7 volt on the 10v rail. (by the zener)


That is your problem. Find out why...

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on March 03, 2006, 07:40:09 PM
Hi every body,

I just realized that i used carbon 5% for the near total resistors instead of metal 1%...
What kind of problems could I meet when using my unit?

I've ordered fairchild semi conductors...are they really crappy (i've read this somewhere)

And when using an input transfo on mnats rev H pcb, the caps marked * are optional?
I'm not obliged to put those on the PCB...Am I right?

thanks

PS:I've read the FAQ on mnats website and lots of threads but I'm still confused.Maybe because it's hard for me to discover at the same time DIY and technical english ... :roll:
Title: All things G1176 - the new "repost" thread.
Post by: audioforge on March 04, 2006, 02:19:48 AM
Gachet.
welcome to the board.
glad to see you ll find that "black market" was not the right board to ask questions.

carbon 5% are ok. original one used thoses. just check they re not too much out of value with your ohm meter.

fairchild 5532 will work. maybe electrome (rue fondaudege) still have phillips 5532AN.(i ve bought some here last year :wink: ).

optional components are optional except you use the LL1540 input traffo.

audioforge
Title: All things G1176 - the new "repost" thread.
Post by: imo on March 04, 2006, 03:46:46 AM
Hello, 1176 circuit testing question:
I have my board stuffed, power supply is clean, passing signal, but things aren't quite 100%. The signal sounds a bit phasey ande distorted, and i don't think i am able to hear any compression.. Anyhow, i used my meter to take some measurements and was hoping that they would make sense to some of you and you could push me in the right direction. One of the things that has been the most interesting and challenging is to learn what to do when you have put everything together, that seems to be the steepest learning curve.

since i was having trouble with the compression i checked out the gr control amp. The rails were fine(30.7, 9.7), but my measurements were quite a bit off inside the circuit.
Q15 c-30.7, b-24.9, e-24.2
Q14 c-24.9, b-25.6, e-24.9
after R70-29.8
Q13 c-30.7, b-26.7, e-26.2
Q12 c-26.7, b-0???, e-4.6

BTW, the rest of the circuit seems to check out pretty close to the specs, its only in the gr control section

I don't know if this info would point to an obvious issue beyond the transistors operating correctly, but any info would be tremendous.
Thanks
Ian
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on March 04, 2006, 09:47:19 AM
Thanks Audioforge :razz:

Ne serais tu pas un Bordelais?... :wink:
Title: All things G1176 - the new "repost" thread.
Post by: imo on March 05, 2006, 04:56:28 AM
update question..
i found an incorrect resistor. I had a 470r instead of a 470k. I replaced, powered back up and now i am having a strange oscillation that seems to start at leg 1 of the 7824 or the + side of the 1000u 50v cap.The middle leg of the 7824is a constant 6.3, leg3 is 30.7, but leg 1 oscillates between 36 and 36.1. the 50v cap oscillates between 35.8 and 36v dc As it goes through the circuit it becomes more extreme, but it seems to start there.
Q15 is 30.7 at the collector, but the base and emitter are moving quite a bit
Q16 is showing dc oscillation on all legs.
Again, this seems confined to the GR section of the unit. I have replaced the 4003's. I am wondering if i should replace the 7824 next, or the caps, a little unsure of what is actually going on.
Any info would be greatly appreciated
Thanks
Ian
Title: All things G1176 - the new "repost" thread.
Post by: ChrisA on March 06, 2006, 10:23:19 AM
I bought a TE62045-ND transformer for my G1176... just wanted to double check that this transformer will work for this project and wanted to ask a for little help in wiring it up correctly...

one side of the transformer has red, green, blue, & black wires...
and the other has red, purple, yellow, and Black wires with yellow covering going half way up all of them...
Title: All things G1176 - the new "repost" thread.
Post by: imo on March 06, 2006, 04:09:46 PM
realized that i used standard 107's instead of 107B's. Perhaps this is accounting for the strange behaviour in the circuit. I have ordered replacements, but wouldn't be furious if someone had any suggestions :?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 06, 2006, 04:39:55 PM
Quote
i used standard 107's instead of 107B's.


Shouldn't matter, really..
Title: All things G1176 - the new "repost" thread.
Post by: imo on March 06, 2006, 05:35:56 PM
Does any of the oscillation stuff make sense to anybody? Does the thinking seem right that it is in the gr section with the strange measurements, or am i chasing a goose?
BTW Jakob, played a show in Aarhus last fall. Beautiful town. Loved the people. Kick records, lovely people
Ian
Title: All things G1176 - the new "repost" thread.
Post by: fucanay on March 21, 2006, 07:08:54 PM
Hi all,

I'm just starting to get all of my parts together and I can't decide between using the input transformers or just using chips. Could anyone give me some real world use opinions on this? I'd like to know if it's worth shelling out the extra $ for. I plan to use OEPs for color as well as cost saving.

Thanks

Matt
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on March 22, 2006, 09:12:02 PM
hi matt,
i've built the G1176 with an IC input and the OEP output and IMHO it sounds very  good.  your opinion and taste in the way a compressor sounds may be different, so this is what i suggest.  install the parts for the IC input option first (a couple of ceramic caps, resistors, dip socket and IC).  not very much money.  if you really hate it, shell out the cash for the output transformer option parts.  you really only waste a few dollars if you don't like the IC option.
cheers,
grant
Title: All things G1176 - the new "repost" thread.
Post by: fucanay on March 22, 2006, 09:52:37 PM
Quote from: "dissonantstring"
hi matt,
i've built the G1176 with an IC input and the OEP output and IMHO it sounds very  good.  your opinion and taste in the way a compressor sounds may be different, so this is what i suggest.  install the parts for the IC input option first (a couple of ceramic caps, resistors, dip socket and IC).  not very much money.  if you really hate it, shell out the cash for the output transformer option parts.  you really only waste a few dollars if you don't like the IC option.
cheers,
grant


I think this is exactly what I'm going to do. Although I'll probably always wonder if the other version sounds a ton better, I'll certainly be happy with it this way.

Matt
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on March 24, 2006, 11:19:18 AM
Hi
Hi I make with rotary switch one switch for Slam - Nuke mode.
When I switch On my VU goes full right. Is it normal?
Thanks
Duka
Title: All things G1176 - the new "repost" thread.
Post by: imo on March 27, 2006, 06:40:46 PM
I have since replaced the 107's but still getting the same response..Any ideas??
Here is the content from the previous post:

Hello, 1176 circuit testing question:
I have my board stuffed, power supply is clean, passing signal, but things aren't quite 100%. The signal sounds a bit phasey ande distorted, and i don't think i am able to hear any compression.. Anyhow, i used my meter to take some measurements and was hoping that they would make sense to some of you and you could push me in the right direction.
On all the 107's in the gain reduction circuit i am seeing a pretty significant oscillation in DC voltage. I can't get a standard reading, rather a wide, quickly changing reading on all of the base and emmiters of the transistors, reading from around 4v to 25v. Are there any obvious spots to look to?? Any tips or directions anyone could point me to?
Thanks in advance
Ian
BTW, the rest of the circuit seems to check out pretty close to the specs, its only in the gr control section
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on March 31, 2006, 05:06:58 PM
On the power supply sections there is a 1100 ohm 1 watt resistor. I had a 1k 3 watt resistor in my supplies. Is that ok to replace the 1.1k with 1k?

Thanks,

Joe
Title: All things G1176 - the new "repost" thread.
Post by: erland on March 31, 2006, 06:46:25 PM
Quote from: "ChrisA"
I bought a TE62045-ND transformer for my G1176... just wanted to double check that this transformer will work for this project and wanted to ask a for little help in wiring it up correctly...

one side of the transformer has red, green, blue, & black wires...
and the other has red, purple, yellow, and Black wires with yellow covering going half way up all of them...


I'd be interested to hear about this as well. I bought a 62063 and a 62062. I opened up one of them and there were 8 different colored wires. This is the first time I install a torroidal transformer.

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 01, 2006, 12:48:01 PM
the primaries should be wired in parallel, the secondaries in series. There should be a datasheet by the part number on the digikey site to tell you which wires these are
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 01, 2006, 12:51:46 PM
I am finishing up the first of a couple of 1176's that i have been wading through, this one using a lundahl input and output transformer. Everything sounds great, and as a line amp alone it is beautiful. The fet seems to be biased correctly and meter reacting pretty well. I am hearing quite a bit of compression even at relatively low levels. I have checked resistor values and everything else on the unit and it all seems in line.
I am wondering what i could do to tame down the threshold a little bit. Everything else seems great, ratios etc, but just wanting a little more clean headroom???
Any suggestions?
Thanks
Ian
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 01, 2006, 01:04:27 PM
Quote from: "imo"
the primaries should be wired in parallel, the secondaries in series. There should be a datasheet by the part number on the digikey site to tell you which wires these are


Thanks. According to the datasheet (http://rocky.digikey.com/WebLib/Amveco-Talema/Web%20Data/62000%20Series%20Low%20Profile%20Miniature%20Transformers.pdf) you'll end up with 4 connections. I'm still confused as to what goes where. I'm going by the Mnats (http://www.geocities.com/m_natsume/1176-wiring.html) wiring guide.

Thanks,
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 01, 2006, 02:29:47 PM
Here is the datasheet for the toroid (http://rocky.digikey.com/WebLib/Amveco-Talema/Web%20Data/62000%20Series%20Low%20Profile%20Miniature%20Transformers.pdf)
. The primaries should be wired parallel (black to violet) (yellow to red) the secondaries should be series, which would tie the two middle wires (red and brown) together. The blue and the Green wires on the secondary would carry your voltage, and the middle two would serve as the ground on your board. Hope this helps
[/url]
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 01, 2006, 03:15:00 PM
Quote from: "imo"
Here is the datasheet for the toroid (http://rocky.digikey.com/WebLib/Amveco-Talema/Web%20Data/62000%20Series%20Low%20Profile%20Miniature%20Transformers.pdf)
. The primaries should be wired parallel (black to violet) (yellow to red) the secondaries should be series, which would tie the two middle wires (red and brown) together. The blue and the Green wires on the secondary would carry your voltage, and the middle two would serve as the ground on your board. Hope this helps
[/url]


Thanks,

I'm still finding this stuff incredibly confusing though. Has anyone drawn out the layout?
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 01, 2006, 03:51:03 PM
That link should take you to a pic that shows the cables. your power comes through the receptacle, in to your switch, which then comes to the black/purple wire. The red/yellow wire connects to the neutral of your receptacle. On the secondary side you should have 3 wires after you tie the 2 middle wires together. They connect to the 24-0-24 marks by the power supply: blue to "24v", middle two to "0", and the green to "24v". Obviously it is important that these connections are solid and that there is no connection between 24v and 0(your board ground). I would suggest going to Mnats site and downloading his wiring diagrams. Read them thoroughly and follow his instructions to build up and check the power supply section first. That way you know you have a solid start and then just be really careful with component placement
Ian
Title: All things G1176 - the new "repost" thread.
Post by: jeroddumas on April 01, 2006, 03:58:26 PM
I gotta get my 1176 running.  Anyone see any problems with this transformer.  

http://www.allelectronics.com/cgi-bin/item/TX-4806/790500/XFORMER,_48_VCT_"#64;_0.63_AMPS_.html.
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 01, 2006, 11:45:12 PM
Jerodumas I just order two toroids from Avel Lindahl factory. Exactly what I needed with mounting hardware. $18 each. I posted a little blurb on the part number in the black market.
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 01, 2006, 11:46:01 PM
Quote from: "JRE Productions"
On the power supply sections there is a 1100 ohm 1 watt resistor. I had a 1k 3 watt resistor in my supplies. Is that ok to replace the 1.1k with 1k?

Thanks,

Joe


Can anyone help me on this?
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 03, 2006, 01:36:30 AM
I posted a few days ago about threshold and wondering how to tame the levels a bit, more clean signal. HAdn't heard anything, but was wondering if there were any ideas regarding these voltages in reference to this.
Q8:E 14.1
     B 14.7
     C 30.4
Q9:E 14
     C 0
     B 13. 4
Q6: E 29.1
      B 28.5
      C 14.7
Q7: E 29.8
      B 29.1
      C 14.7

According to Gyraf's scematics everything is dead on until the base of Q8 and Q9, which are both being fed by the collectors of Q6 and Q7. These are the BC 560's. I am basically off by a little more than .6v from the collectors of the 560's on. I don't know how significant this is, and if i should replaced these? The output voltage is 14.1, .7 high.
Any information would be great
Thanks
Ian
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on April 03, 2006, 11:25:08 AM
Question 1: My resistor R67 is 31.75Kohm. It should be 38.3Kohm. Should I replace it, or is it not that critical enough?

Question 2:
Can R87 be 1Kohm instead of 1.1Kohm?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 03, 2006, 11:40:47 AM
Q1: not critical.
Q2: you NEED 1K1 here. Do a search to find out why.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on April 03, 2006, 11:59:42 AM
Allright. How about 0.6W? Cant find 1.1k 1W...
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 03, 2006, 12:24:02 PM
Quote from: "gyraf"
Q1: not critical.
Q2: you NEED 1K1 here. Do a search to find out why.

Jakob E.


Jakob, I searched all 55 pages, plus 20 other posts. They only thing I can find on the 1k1 resistor is that you need a 1k1 and not why. I would like to understand why. If you have time to re-explain this I would appreciate it.

I have a box full of 1k 5% 3 watters. Can I go through them and find one that is @ 1k1 and use it?

Joe
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on April 04, 2006, 08:35:07 AM
Anyone ever use a different output transformer?  I'm using the gustav boards.....  wondering if I can use a stancor wf30 (utc a20 clone) on the output......   Basically, I have everything but the output transformers to build two, and I'd really like to build em.....

billy
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 04, 2006, 11:36:05 AM
Why not just try it?
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on April 04, 2006, 12:22:29 PM
I would suggest an update to the pcb layout of the 1176, either one 100R and one 1Kohm in serie, or 2 in parallel = 1.1Kohm.
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on April 04, 2006, 04:33:31 PM
sounds good jakob, i think i will ;]

unkown territory, again......

i'm going to guess that I may need to change a couple resistors and caps?

it's 600:600, but can be wired for quite a few ratios.  i think 50, 150, 300, 600  each side.

I'm just not sure if I'll be able to get the gain out of it.

billy

edit:  i think jakob was talking to the guy ahead of my previous post, regarding the 1k1 resistor situation... pay no mind to my newb banter
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 04, 2006, 05:18:28 PM
I think the 1.1 being 1w as opposed to the 1/4w on the rest of the board would be the major difference and probably makes it easier to just have the one
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 05, 2006, 01:40:10 PM
Quote
That link should take you to a pic that shows the cables. your power comes through the receptacle, in to your switch,


The power switch? I still haven't gotten that since I don't know the parts number...

Quote


They connect to the 24-0-24 marks by the power supply: blue to "24v", middle two to "0", and the green to "24v".


So both "24v"s are the same?

Quote

  I would suggest going to Mnats site and downloading his wiring diagrams.


Do you mean this page? http://www.geocities.com/m_natsume/1176-wiring.html


I might have to end up asking someone to do this for me for pay. I didn't know it would be this difficult.

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 05, 2006, 02:39:23 PM
I would encourage you to try this. The forum can be really helpful and i started this with abolutely no electrical knowledge at all. You do need to spend some time on the forums...If you use the search engine you can find Greg's parts list, he is a frequent poster and his information is very helpful. He has a comprehensive list for many of the projects listed here. Once you get the parts its really just a matter of following the pretty thorough discussions and working slowly and methodically
Ian
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 05, 2006, 03:07:04 PM
The search engine doesn't work for me on this thread. I get the following error: PHP Fatal error: Maximum execution time of 30 seconds exceeded in D:\users\prodigy\Inetpub\wwwroot\forum\db\mysql4.php on line 214

I think I used Greg's parts list. The mains switch isn't listed though. I was planning on using Mouser parts # 103-0012, which is a DPDT switch. I got that number from a G9 BOM.

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 06, 2006, 12:40:47 AM
Greg's list uses a rotary switch, two pole i think. It is aesthetically nice, though a two pole toggle switch would work just as well
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 06, 2006, 11:44:09 AM
Thanks. It looks I went by fallout's list.

I thought that it wasn't advised to use rotary switches for mains power for some reason. All my rack gear has either push-button or rocker switches. I also saw on a thread here someone commenting on the rotary switches.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on April 06, 2006, 04:21:11 PM
erland, you are correct. However, Lorlin makes a rotary switch specifically for mains. I don't have a part number, but I got the datasheet of their website some time ago. In general, just make sure the switch is rated for high voltage... most toggles are rated for mains. If unsure, check the datasheet.
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 06, 2006, 04:54:25 PM
I bought a lot of parts from www.apexjr.com  He had the urei style knobs for 75 cents each, he has a rotary on/off switch for 79 cents each. He also has toroids for $17 but I found them from the manufacture cheaper with hardware.  Any Steve at apexjr.com is a real nice guy, and the prices on some of this stuff like knobs are excellent. $0.75 for a skirted knob, and for the small ones too.

(http://img.photobucket.com/albums/v362/jrepro/1176Clone1.jpg)

Almost done. Just waiting for the input/output iron.
Title: All things G1176 - the new "repost" thread.
Post by: Esset on April 07, 2006, 02:29:19 AM
Got one of my two 1176's to work yesterday!!! The distortion-problem were due to not having shielded pin3 on the XLRs and bad soldering at one point.

My Second unit is still not working and I really need some pointers on where to look next.
My voltages are to high on all the BC107 and BC560. (See list below)
The +30V and the -10V are fine, and the +30V "rail" along the board is all good.
The signal comes in fine and goes excellent through the IC-balanced inpout, into the BF245A out and in to Q2, where it disappears (due to the wrong voltages???)

Have checked, re-checked and tripple-checked and there are no loose wires, no shorts, no wrong placed polaritys.

Some resistor values are of a bit too. Took them away, measured the new one before I put it in place, perfectly fine, but when in place they change valu(!!!), the 15Kohm R53 is suddenly around 7Kohm, why?
   


Here are my f-ed up voltages
     E    B   C
Q2  5,7  3,8  7
Q3  6,2   7   6,7
Q4  5,7  6,2  30
Q5  26    26  26
Q6  27    26  27
Q7 27,6  27,6 27
Q12  5    5,6  5,6
Q13 5    5,6  30
Q14 27   22   26
Q15 27   26,4 30

Just broken transistors that are screwing it up??
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 07, 2006, 09:39:04 AM
Thanks Greg. What's considered high enough voltage for this project? over 24v?

Could someone let me know what hardware I need that's not included on the parts lists so I can order it and then get to the actual wiring?  ie. torroid screw, XLR panel mount screws, IEC screws.

Are XLR panel mount screws 3/64th flat head?

Thanks a lot. I would really appreciate it.
Title: All things G1176 - the new "repost" thread.
Post by: Nadege on April 07, 2006, 10:22:24 AM
Hi,

I'm currently building a 1176 based on mnat's PCB but I cannot find the R50 on the board !!!!! It's said that this resistor is not in the gyraf version, OK, but where is it in the mnat's version?????

I'm also wondering what are the cap named c* for ?

And also if I have to place C16 (wich seems optional) into place. It's said in the BOM that C16 (33pF) is legacy item? (Don't understand because of my poor english) and that pin 89 is not connected on TL071 what I can see on the PCB

That's a lot of question, but I'm a bit confused especially that I'm new at DIY

Thanks for your help

 :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 07, 2006, 11:00:26 AM
Quote from: "Nadege"
Hi,

I'm currently building a 1176 based on mnat's PCB but I cannot find the R50 on the board !!!!! It's said that this resistor is not in the gyraf version, OK, but where is it in the mnat's version?????

I'm also wondering what are the cap named c* for ?

And also if I have to place C16 (wich seems optional) into place. It's said in the BOM that C16 (33pF) is legacy item? (Don't understand because of my poor english) and that pin 89 is not connected on TL071 what I can see on the PCB

That's a lot of question, but I'm a bit confused especially that I'm new at DIY

Thanks for your help

 :thumb:


Not so sure I'm the best one to answer this since I'm not a native English speaker, but "legacy" means something old, not in use. http://www.answers.com/legacy&r=67

All the markings with * for use when not using the optional input transformer.

Some more posts about R50: here (http://groupdiy.com/index.php?topic=51884&highlight=r50&sid=9744d68dbfedb296a7389cbe84b1bae0#51884l) and here (http://www.groupdiy.com/index.php?topic=7405)
Title: All things G1176 - the new "repost" thread.
Post by: Nadege on April 07, 2006, 11:11:27 AM
Ok thanks for the answer

what are the value for the different c* capacitor, it's not mentionned in Mnat's BOM
Title: All things G1176 - the new "repost" thread.
Post by: Esset on April 08, 2006, 03:47:45 AM
Quote from: "Esset"
My Second unit is still not working and I really need some pointers on where to look next.
My voltages are to high on all the BC107 and BC560. (See list below)
The +30V and the -10V are fine, and the +30V "rail" along the board is all good.
The signal comes in fine and goes excellent through the IC-balanced inpout, into the BF245A out and in to Q2, where it disappears (due to the wrong voltages???)

Have checked, re-checked and tripple-checked and there are no loose wires, no shorts, no wrong placed polaritys.

Some resistor values are of a bit too. Took them away, measured the new one before I put it in place, perfectly fine, but when in place they change valu(!!!), the 15Kohm R53 is suddenly around 7Kohm, why?
   


Here are my f-ed up voltages
     E    B   C
Q2  5,7  3,8  7
Q3  6,2   7   6,7
Q4  5,7  6,2  30
Q5  26    26  26
Q6  27    26  27
Q7 27,6  27,6 27
Q12  5    5,6  5,6
Q13 5    5,6  30
Q14 27   22   26
Q15 27   26,4 30

Just broken transistors that are screwing it up??


ANy ideas/tips on where to look?
Title: All things G1176 - the new "repost" thread.
Post by: mnats on April 08, 2006, 06:19:47 AM
Quote
All the markings with * for use when not using the optional input transformer.

Not quite. Check the first item in my 1176 FAQ (http://geocities.com/m_natsume/1176_FAQ.html).
Quote
It's said that this resistor is not in the gyraf version, OK, but where is it in the mnat's version?????

Please remember that my boards are based on Jakob's original design. So most things that apply to the G1176 will also apply to my boards.
Quote
Took them away, measured the new one before I put it in place, perfectly fine, but when in place they change valu(!!!), the 15Kohm R53 is suddenly around 7Kohm, why?

When you put a component into the circuit, it will interact with other components. So if the resistor is in parallel with another resistance (even if it doesn't seem obvious) you will get a different reading.


You said your signal disappears around Q2 - sounds like you are getting very close to the problem! I'm not nearly as good as Jakob or some of the others who can troubleshoot from a distance but I think you might want to check your active devices. Got a transistor tester?
Title: All things G1176 - the new "repost" thread.
Post by: Esset on April 08, 2006, 11:21:57 AM
Quote from: "mnats"
Quote from: "Esset"
Took them away, measured the new one before I put it in place, perfectly fine, but when in place they change valu(!!!), the 15Kohm R53 is suddenly around 7Kohm, why?

When you put a component into the circuit, it will interact with other components. So if the resistor is in parallel with another resistance (even if it doesn't seem obvious) you will get a different reading.

Yes, this dawned on me when I took a step back from the soldering iron.


Quote from: "mnats"

You said your signal disappears around Q2 - sounds like you are getting very close to the problem! I'm not nearly as good as Jakob or some of the others who can troubleshoot from a distance but I think you might want to check your active devices. Got a transistor tester?


No transistor tester, am though about tot order some parts for other projects, will order som spare transistors aswell. Thanks for the help mnats and I hope somebody else has any ideas!
Title: All things G1176 - the new "repost" thread.
Post by: erland on April 09, 2006, 12:16:00 PM
Quote from: "mnats"
Quote
All the markings with * for use when not using the optional input transformer.

Not quite. Check the first item in my 1176 FAQ (http://geocities.com/m_natsume/1176_FAQ.html).
?


Oops. Sorry.  :oops:
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 14, 2006, 08:16:16 PM
Both of my compressors are not working yet. UGH!

Compressor #1 Transformer input: Signal is distorted but it appears to compress. 30 and -10 voltages are right at the power section.  The voltage on the TL071 seems suspect. 19v on the pos, and -9 on the neg V post. (actually both compressors measure the same on this pin).

Compessor #2 Electronic Balanced input: No signal going through. The signal seems to get cliped at the 5532 opamp. On my scope the signal become small and very square. The voltage seems posibly high on one side, and -9v on the other neg leg.  Because its electronic input, I am guessing that the signal is not making it through the first stage.

What would cause the voltage to be low on opamps in both compressors?

Do I need to set up bias, before checkng voltages on the opamps?

HELP!

Joe
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 16, 2006, 08:41:58 PM
Well seems no one is monitoring this page anymore......


I'll ask my question anyway.  I have gotten the first of my compressors to pass audio and compress. It sounds pretty good. I HAVE NOT CALIBRATED IT YET. I do not know if that is part of my problem or not. In by-pass (Meter switch all the way counter clockwise) the unit has a ton of gain.  I have to turn the output down. In GR or VU the unit has moderate gain.  I mean enough to be louder than the original input level if I remove the compressor, but not over the top. But in the bypass mode, it gets really loud, and I have to adjust the output pot.

Question 1: Does the bypass mode still go through the amp?

Question 2: Under the higher ratio's the output pot seems to react differently. Meaning that it seems to have linear output in 4:1 mode, but in 20:1 mode it the center portion of the pot does not seem to make a difference. The begining and end portion of the rotaion makes the most significant gain. If this is make up gain, should it be linear no mater what ratio is selected?

Again, I have not calibrated the unit, and just left for LA for a few days. So I will have to calibrate next weekend.

Help?

Joe
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 17, 2006, 09:12:56 AM
Hi Joe,

Yes, I still read this thread - but it seems that most problems has been covered already on the previous pages. To sum up:

- Check for shorts on the PCB.
- Check for wrong components, orientation, and interwireing.

This covers more than 99% of G1176-related problems.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 17, 2006, 03:02:13 PM
Gyraf, At 57 plus pages, this post is difficult to find specific issues anymore.  If you possible, please answer the two questions that are not related to parts/shorts ect. My units are now both functioning, but I have performance questions.  I searched but did not find related topics.

Question 1: Does the bypass mode still go through the amp section, or just the output transformer?

Question 2: Under the higher ratio's the output pot seems to react differently. Meaning that it seems to have linear output in 4:1 mode, but in 20:1 mode,  the center portion of the pot does not seem to make a difference. The begining and end portion of the rotaion makes the most significant gain changes. If this is make up gain, should it be linear no mater what ratio is selected?

Thanks for any help.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 18, 2006, 03:57:59 AM
Quote from: "JRE Productions"

Question 1: Does the bypass mode still go through the amp section, or just the output transformer?


Take a look at the schematic: the only thing the bypass switch does, is take out the sidechain signal, i.e. disable gainreduction. No change in audio signal path.

Quote from: "JRE Productions"

Question 2: Under the higher ratio's the output pot seems to react differently. Meaning that it seems to have linear output in 4:1 mode, but in 20:1 mode,  the center portion of the pot does not seem to make a difference. The begining and end portion of the rotaion makes the most significant gain changes. If this is make up gain, should it be linear no mater what ratio is selected?


Output pot should react the same no matter what ratio. But input pot will behave like you describe at high ratios, because it'll push into gain reduction (holding steady level) untill you run out of FET attenuation at the other side of 40dB GR, at which point the ratio in effect reduces.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: on April 18, 2006, 08:27:57 AM
Quote from: "JRE Productions"

Gyraf, At 57 plus pages, this post is difficult to find specific issues anymore.  If you possible, please answer the two questions that are not related to parts/shorts ect.
Thanks for any help.

That's a bit harsh on Jakob mate
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 18, 2006, 11:59:48 AM
Jacob, I did not mean anything to sound harsh. I read and reread all 57 pages, and used the search function and still can not seem to find what I needed. It almost would have been better to have seperate topics for each trouble. Easier to search.

Thanks for the help.
Title: All things G1176 - the new "repost" thread.
Post by: imo on April 18, 2006, 09:59:20 PM
It is a bit overwhelming, and i have been unbelievably frustrated at times with projects i was working on, largely due to my lack of knowledge and consequential lack of understanding about problems i ran into, but the whole forum is done as a BIG favor to those of us who are trying to learn about, and build electronics. I have found this to be an enormous asset in understanding and building the gear that all seems to point back ultimately to Jacob's site and willingness to share design ideas and information. It takes a lot of time to compile all of this information, and i am really impressed that he, as well as  so many others volunteer this. I guess this is what impresses me about the community, all of the people that give and help those of us that have little to offer in return, and i want to thank everyone in being so helpful. I would keep in mind that this is all done without any type of return other than a thanks so we all owe quite a bit of that.
Not trying to be too preachy, i just have seen Jacob already answer the same question so many times, a couple were my boneheaded queries, and i want to make sure to keep those channels open as they have been really great so far
Ian
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 24, 2006, 02:09:38 AM
Well both units are up and running. I really like both of them (1 with input iron, one without).  They sound wonderfull. I have a full compliment of compressors in the studio and these sound as good as any.

One of them I am having troubles with the tracking pot.  Seems it only moves the meter 1 db or so either way. Even when I change the zero control a little each way. When I have 6db of gain reduction, I can only get the meter to about -10db.  I will have to check a few more resistors around the trim pot.

Observations:

The release pot seems to really effect the output too.
The attack pot seems to really affect the threshold too.
The tracking (even on the working one) seems to not be all that great.  I find its best to just use my ears.  
A little goes a long way with the compression.
The compression is quite smooth, but can really slam too.

Thanks for all the help with my lack electrical knowledge.

Joe
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 24, 2006, 02:34:53 AM
Quote from: "JRE Productions"
Well both units are up and running. I really like both of them (1 with input iron, one without).  They sound wonderfull. I have a full compliment of compressors in the studio and these sound as good as any.


 :grin:  :thumb:

Quote from: "JRE Productions"

One of them I am having troubles with the tracking pot.  Seems it only moves the meter 1 db or so either way. Even when I change the zero control a little each way. When I have 6db of gain reduction, I can only get the meter to about -10db.  I will have to check a few more resistors around the trim pot.


This may be because of unmatched FET's. Try changing the meter driver FET 'till you get useable meter tracking (this is why sockets for the FET's are a great idea)


Quote from: "JRE Productions"

The release pot seems to really effect the output too.
The attack pot seems to really affect the threshold too.


It should, as different timing will rectify different amounts of audio AC.

Quote from: "JRE Productions"

The tracking (even on the working one) seems to not be all that great.  I find its best to just use my ears.  


For better tracking, you may experiment with changing audio attenuator FET's.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 24, 2006, 10:50:04 AM
Jacob,

Thanks for the help......um...and the persistance to investigate things on my own. I did learn valueable lessons on checking and rechecking solder joints (or lack of), componenent values ect.  I completed two units at the same time. Both had the same components wrong (4.2K instead of 4R2).  Once I found the first one, the other was a no brainer.  I also had a wire inverted on one (15/17), and two resistors that only one leg was solder on.  Funny how you check and double check when installing the components, and then later find wrong ones anyway.  

I will try a new FET for the metering. Thanks,

Joe
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on April 25, 2006, 03:44:09 PM
Jacob or anyone...

one last question. I used early API #7 VU meters for my compressors. These are true VU meters. I did not give this any thought until last night. Do I still need to add the 3K6 or 3k9 resistor in series with the meter? Or does the circuit board compensate for this resistance as part of the design?

The meters seem to function fine with out any added resistors between the PCB and the meter. But if needed I can open them back up and add it in.


Oops maybe two questions...

For meter lights I found a 28 vdc bulb like the #47 style. I came off the circuit board and used a 500 ohm 3 watt resistor to drop the voltage to about 21 volts under load of the light.  This seems to be a pleasant brightness for the meters. Not to bright, but not dark either. With the 25-0-25 volt toriod, am I overloading it at all? I think I got the 30va toriod.

All is working and nothing seems to get to hot.

Thanks again

Joe
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on April 26, 2006, 05:17:41 PM
just wondering, has anyone used alternate input transformers on this one?  i have oep's for the outs, but I was thinking of using some stancor wf30's (same as utc a-20's) for the input.  I read somewhere in separate thread (talking about the o12) that someone had used an a20 on the input, but i'm not sure if he meant the g1176 or a real 1176.... anyway, i'm just wondering if I can wire it to the pads for the lundahl and terminate it the same way or if i'll have to do things differently.  

getting a t-attenuator, unfortunately, is just not in the budget

billy
Title: All things G1176 - the new "repost" thread.
Post by: Esset on May 02, 2006, 04:49:08 PM
okey, here we go again! One channel up and working and loving it! One is still making me sleepless at night.

Checked the whole board (i think) capacitor oriantation, resistor value (compared to the working unit), solder blobs, shorts, unsoldered cables.

found the following, had switch places on the 180ohm and 1Mohm resistors. Here was the big screw up on my voltages, and the signal dropping out around Q2.
Switched them and the unit started passing audio!!!

Meter wasn't working so I switched the TL071 and the BF245A, and it started moving a bit in VU-mode. But not nearly as much as on my other fully working unit.

Its not compressing at all, and the meter doesn't work in GR-mode (probably due to the Gr not working  :? )

Really need your help now, running out of places to look!!!

Voltages as they look now.
     E-B-C
Q2 0,54-0,87-177
Q3 1,15-1,77-11,96
Q4 11,6-12,4-30
Q5 4,4-4,4-28,6
Q6 28,8-28,8-14,3
Q7 29,4-28,8-14,3
Q8 13,7-14,1-30
Q9 13,6-13-0,003
Q12 4-4,2-14,8
Q13 14,4-14,8-30
Q14 2,4-3,4-16,3
Q15 16,3-16,3-30

Some look good others not so good. Are the changes so big that the no-compression problem should be due to them, or is it in some other area.

On page 40 or something soundguy seemed to have a similar problem but there was no reply from with were the problem were, or if he fixed it (kinda taking for granted that he fixed it)
Title: All things G1176 - the new "repost" thread.
Post by: Esset on May 03, 2006, 03:46:55 PM
never mind my last post, came home today powered the unit up andit just started working, must have been to tired yesterday or the unit just might needed a night to rest  :shock:
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 04, 2006, 01:59:27 PM
Well, I've figured out how to wire my stancor wf-30's for 600:600, and see where to solder to the input transformer section of the board....

question is, will I need those 2 10k resistors as specified for the lundahls?  Or possibly something else?  

I've left them out for now, everything else is stuffed, I was going to go ahead and begin wiring.

Billy
Title: All things G1176 - the new "repost" thread.
Post by: Aryuserius? on May 10, 2006, 02:56:27 PM
searched, but couldn't find a similar problem.

No 30v at output of 7824 regulator.  -10v ok.  VU meter went to zero @ power up then came back to -10.   when unplugged and plugged back in, meter just goes to -10 now.   4003 diodes ok.  replaced voltage regulator, again-started ok then within 2 seconds meter went back to -10.  Any ideas?  POssible dead short in the output line of the voltage regulator?  Any help is appreciated.

-Mike
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on May 11, 2006, 01:18:36 AM
Quote
POssible dead short in the output line of the voltage regulator?


If you have input voltage to the regulator, but no output voltage at all, then yes.

Check - as always - for shorts between traces. Check for correct type and orientation of transistors (specially the output devices)

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 11, 2006, 06:34:47 AM
well, I have both of my units passing audio.  I think on one I have an obvious joint or wiring issue, as a 'wiggle' seemed to cause quite a stir.  I'm going to take a closer look at it.

The other, I can't quite get.....   it passes audio, but distorted.  -10dbFS with input and output all the way up.  

It's passes the same audio in bypass/gr/vu modes, but although the output is quite low, the VU (in VU mode) reads very hot, the needle smacking the right side back and forth.

Bypass mode is the same, but with no meter activity.

GR mode sounds the same, although the needle simply sticks to the right constantly, no movement whatsoever regardless of audio.

I'ts 630 am, so I'm going to sleep, but I just can't figure that one.  All the wiring and joints do appear to be alright.  The other unit only seems to have a bad joint on one interconnecting wire.  

Well, tomorrow's another day.

Oh, almost forgot to ask....  I just realized that I didn't stuff C*1 and C*2 (100uf lytic and a .1 poly).  I'm using mnats revH board, and I didn't see those listed on the BOM.  Are they:

a Needed all the time? or
b. Needed if using an input transformer???
or c. Not needed at all?

thanks, and good morning EST GMT-5

billy
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 11, 2006, 01:44:27 PM
Also, I left C* (1000uf lytic) and C16 (33pf) unstuffed.... C* was unlisted on the mnats BOM and C16 looked like it was left out.  SHould I try using these?

thanks,

billy
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 11, 2006, 03:07:14 PM
So, it appears that during those tests I had the tl071s backwards.  Something confused me and I got it backwards....

I'm going to assume they aren't good, and I can either run out and pick some up, or can i use an OPA134 in its place?

Also, I double checked for cold joints and shorts, and the one thing I found, aside from double soldering some suspect looking joints, was an unsoldered leg of CR1, the joint closest to Q6

Hopefully that was the source of some of my troubles.  

I think I may go pick up some extra bc107's and bc560's and some tl071s, although If they work in this cct I do have some opa134's.  Luckily I bought 25 bf245a's, so I have plenty of spares there.

Then when I get back I can start dbl-checking voltages and R values.

billy
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 11, 2006, 05:20:29 PM
god, i'm the worst, i'm sorry to post so many crap comments just to get to the next step on my own....

anyway, i began checking resistors by color code, and voila, R71, 7.68k, was a 221k......  futurlec sent me a bag of 20 221k R's labeled 7.68k, so, lesson learned... Double check before stuffing man!!!!

<----idiot (impatient probably)

i see now how many problems and how much time that saves

so, hopefully that was the source of many of my issues, although i'm going to keep double checking.

I was going to ask if a 7.5k would be ok, but I've got a 10k and a 33k in parallel at 7.66k and 7.78k, which is within 1% tolerance, so....

thanks guys, even if it's just so I might vent and think 'out loud'

billy
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 12, 2006, 01:41:29 AM
well, i think i may have answered my own questions with dumb luck and guesswork (only a slight amount of logical deduction)

anyway, 1st channel is working beautifully.  I mean really beautfiul!   incredible.

of course i have *nothing* to compare it to.

I've never owned a hardware compressor, and i've never owned anything with transformers, guitar amps aside.  So I can't compare, or say anything like that, but after coming up on tascam cassette 4 track mic pres, and soundblaster live + behringer, to a mackie 24/8 with a 20 bit Layla, I must say that md421->green pre->G1176 sounds extremely pleasing.

stancor wf-30 on the input and oep on the output, mostly pretty good components.  

mci VU meters, and some how I fit two units in this one box.

I'll post some pics tomorrow after the first session with these puppies (provided I can get the 2nd guy going ;]

thanks so much everyone for putting this together....

I honestly can't express my gratitude enough for this place....  It showed me that I could record with professional tools on a medium-low budget, and it seems like ages since I sold my mackie and started buying parts (headache).  Really paying off over here.  

This first band since my 'revamp' or whatever is a metal band, a genre i've never recorded before, but i'll post some all diy samples in the brewery soon enough.

thanks again everyone!

billy
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 12, 2006, 03:37:33 AM
well, kind of spoke too soon.... seems i've searched and searched and found a few others who have had the problem, but can't find anything more than that.

my one channel is still excellent, and the other channel sounds and compresses just fine, although its not been calibrated yet.  I set the q bias, and dist trim, although i'm using a free computer distortion meter, i got it as low as that program said it would go.

anyway, when I go to set the tracking and the GR meter, I can't get the meter to move whatsoever.  I noticed the trimpot for gr zero was opposite the other unit, so i switched it around, but its still not budging.

seems i've turned this thing forever both ways, not a hair of movement.

meter reads fine in VU.  passes audio wonderfully, and is def. compressing, maybe not quite right yet, but def. compressing.

thanks for any thoughts anybody might have

billy
Title: All things G1176 - the new "repost" thread.
Post by: JRE Productions on May 12, 2006, 10:47:00 AM
It seems to me Jacob said the TL074 was used for the meter. (I think...someone may need to correct me.) But if you had some earlier problems with power, you might want to change that one. If you used sockets, just pop one out and switch it to the other. But ....just so you know, I am not much more knowledgable than you at this...

Joe
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on May 13, 2006, 09:53:07 AM
Hi everybody,

I've just finished stuffing and wiring my first board and it's passing audio,the vu meter works?but it's not compressing at all and the vumeter   is not working in GR mode.
All voltage looks fine.I tried different FETs but the problem is still there.

What are the voltage needed around Q2?
What should I do now?This problem looks recurant;is there any procedure in that case?I didn't find anything(to many posts)?

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: imo on May 13, 2006, 12:33:43 PM
If you go to Gyraf's site, www.gyraf.dk, he has a pretty accurate schematic of the 1176. There are voltages listed for each of the transistors, and it will give you a good idea if you are in the ballpark
Imo
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on May 13, 2006, 01:40:44 PM
Hi

I already have this schematic and checked voltage with it.But nothing is specified around Q1.
The input stage as well as the output seem to work fine.Just a very little less gain when bypassing the unit.
Enough gain ,no hum.The voltages seem to be correct too.No shorts beetween traces.
But no compression and the GR mode doesn't work.The q bias and tracking pots don't make anything
My voltages are:

         E      B      C

Q2 : 0,5    0,9    1,6
Q3 :  1      1,6   11,8
Q4 : 11,2  11,8  28,6
Q5 :  4,1    4,6   26,9
Q6 : 27,5  26,9  13,6                                                                                                                    
Q7 : 28,1  27,5  13,6
Q8 : 13,1  13,7  28,6
Q9 : 13     12,4   0
 
Q12: 3,6     4,2    14,8
Q13: 13,6  14,7    28,6
Q14: 2,7     3,3    15,8
Q15: 15,3  15,8    28,6


Q1:  D0     S0    G0 => Is that normal?
Q10:D17,8 S0,4 G0

Voila;Help is needed THANKS
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on May 26, 2006, 06:05:22 PM
hooooooo

Nobody has an idea?!!

Please?
Title: All things G1176 - the new "repost" thread.
Post by: fucanay on May 26, 2006, 08:27:23 PM
I just finished the front panel for my first G1176 and I plugged it in and it sounds great even without having done the calibration.  I've never calibrated anything and I'm not entirely sure my DMM is right for it. I'm supposed to be reading mV but I think I can only do down to a tenth of a volt AC. Anything less show 0.0 . So I think I have some problems on that front. Anyone care to point me at a decent DMM for this?

But I got my front panel mostly finished.

 Picture (http://diy.fischerworks.com/pictures/100_2222.JPG)

Unless I can find some rub on lettering, it'll be getting the Sharpie labeling treatment. I love the big meter I got from Jollyted. I don't think I'll even bother backlighting it.

Matt
Title: All things G1176 - the new "repost" thread.
Post by: spacecho on May 28, 2006, 08:28:38 AM
Hello Gachet,

i had a similar problem of no compression in my 1176. I used sockets for the bf245a's and i found that the connection was intermittent. When i soldered these parts in it works fine.

I suspect that you have either burned them when soldering them (i think these parts are quite sensitive to heat so you really need to be careful when heatsinking them....) or if you have used sockets they are intermittent. (i found my sockets a little tight and it was hard to get the transistor legs into the holes.

you mentioned that your input and output gain is ok. The circuit will behave this way without the bf245's in place so i think thats where the problem lies...

hope this helps
Title: All things G1176 - the new "repost" thread.
Post by: fucanay on May 28, 2006, 12:31:11 PM
Quote from: "RogerFoote"
Quote from: "fucanay"
I just finished the front panel for my first G1176 and I plugged it in and it sounds great even without having done the calibration.  I've never calibrated anything and I'm not entirely sure my DMM is right for it. I'm supposed to be reading mV but I think I can only do down to a tenth of a volt AC. Anything less show 0.0 . So I think I have some problems on that front. Anyone care to point me at a decent DMM for this?

Matt


Matt

Any "decent" DMM that has a mV range is ok. I use Flukes mostly, but we have a CEN-TECH P35761 ($10 Harbor Freight special) that will do ok for mV measurements. The CEN-TECH has a low range of 0-200mV.


Thanks Roger,

My DMM has no Mv range on it. It only has a 250 and 700 AC setting on it. There is a Harbor Freight over in Newark, so I'll go see what I can find.

So when it says that I should get 50mV on the input, that mean at the TRS jack between the the Ring and Tip or does it mean from the Tip and Sleeve?  :?

Matt
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on May 28, 2006, 02:38:02 PM
Hope this helps out, but you want 50 mv between tip and sleeve matt.  

How are you generating your signal?  I used wavelab to do mine, don't have a signal/function generator yet.....  If you're going that route, you can just take an output from your sound card.

Anyway, I plug a trs into an output of the line amp outs on my motu, but a any soundcard output will get you 50mv.   Anyway, wherever you're getting your signal, clip your dmm onto tip and sleeve (pin 2 and pin 1 on an xlr, respectively) to get your 50mv.  

the important thing is that you set unity gain on the 1176, just as long as it's as low as possible... I believe the idea is to set unity gain on the line amp while insuring that when you switch to GR mode no compression will take place until you raise the input signal (with your computer or signal generator volume, not the 1176)  if your dmm only goes down to 100mv, that should work, pending an expert opinion... i'm pretty sure a 100mv signal wont bust the threshold.

Then go ahead and probe the output, tip and sleeve, and set the input/output until you get that same 50mv.   Then follow the rest of the procedure to get -6db gain reduction.

Two meters is a really good idea for this step.  Its really hard to set an input signal that gets that -6db of gain reduction when you have to jump your DMM from input to output, back and forth, and set the input signal at the same time.


I have a couple questions as well, however...

Also, is there a ballpark range for the input signal that should achieve the  -6db?  I seem to endup with a pretty damn high input signal to get the compression going.

And can this be done with a scope, hooking up input and output signals to the scope?  I just got a decent dualtrace scope, and if I can do it like that I have a feeling it would be way easier.  Wouldn't a normal dmm, even a fluke true rms, not really be as good as a dedicated ac mv meter?  I seem to recall people mentioning that dmm's don't track all that well as frequency increases.

Billy
Title: All things G1176 - the new "repost" thread.
Post by: fucanay on May 28, 2006, 04:40:36 PM
The good news is that you all helped me adjust this thing and I'm done. Suddenly the meter makes more sense now too. I went out to Harbor Freight and got the new DMM with a mV setting on it and everything went perfect from there.

Billy,

I used Logic Pro's Test Oscillator to output the signal out of my M-Audio Delta 1010. It worked pretty good. Resolution from Logics faders was a bit hard to deal with, but I eventually got it using a combo of the channel and master faders.

But I think I'm done with this one, I just need to pretty up the wiring and close the case. Then it's onto the next one which is mostly complete. I just wanted to go through all of the wiring and calibrating on one unit to make sure I kept focused.

I love when something gets done.

Thanks for all the help.

Matt
Title: taming compression threshold
Post by: imo on May 30, 2006, 11:34:44 AM
I have my 1176 up and running, did the ground cut, reduced the noise floor quite a bit. ALso matched the FET's, whiched really helped with the meter tracking.
I am getting compression pretty early on, with the unit properly biased and set up. I find myself having to keep the input knob around 9 oclock if i just want a few db's. I was wondering if anyone had any ideas on the best way to tame the threshold on the unit. Would it be a resistor to the input pot, or would i be better off ammending it somewhere else?
Thanks
Ian
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on May 30, 2006, 11:52:33 AM
..the only really sensible way to alter threshold sensitivity is finding fet's with different cutoff voltage. The BF245A will get you in the approximately correct range..

Jakob E.
Title: voltage checkplot
Post by: kato on June 11, 2006, 09:02:40 PM
I used Synthetic's voltage checkplot to create this one for the reverse side of the board - if it's useful to anyone:

Voltage Checkplot: Reverse - right-click, save as... (http://dongrock.com/assets/documents/Mnats1176/calibration/checkplot_reverse.png)

It's the same as Synthetic's version except it's for the backside of the board rather than the front. The only advantage is that the voltages are printed left-to-right. (easier to read)

Here's the front side. (http://dongrock.com/assets/documents/Mnats1176/calibration/checkplot_front.png) Though I'm not sure what good a frontside voltage check is - there's no way to reach most of the spots.

edit 24 hours after this original post I realized I posted a "mirror image" of the reverse. Sorry if anyone printed it and wasted their time. It's now corrected.
Title: all my voltages are low...
Post by: kato on June 11, 2006, 10:41:26 PM
I did a quick check of my voltages and nearly all of them are low!

Examples:

.86v should be 1.02v
1.73v should be 1.76v
25.8v - correct
0.54v should be .51v (higher)
11.9v should be 11.5v (higher)
12.3v should be 11.68v (higher)
16.68v should be 17.25v
4.26v should be 4.5v
14.82v should be 15.3v
4.0v should be 4.03v
27.8v - correct
30.3v - correct
14.42v should be 14.54v
-9.76v should be -10v
3.4v should be 3.51v
16.75v should be 16.72v
29.1v - correct
14.6v should be 14.06v (higher)
29.7v - correct
28.4v should be 28.6v
4.26v should be 4.98v
4.46v should be 4.54v
13.95 should be 13.35 (higher)
13.98 should be 13.40 (higher)
and
30.3v should be 35.4v!!!! (this one is way off)

Aside from this last one, do any of these voltages look like cause for alarm?

None of the switches, jacks, knobs, meters, or lamps are connected - just the PCB in a case connected to the transformer. (not even an on-off switch yet.)

Also, I checked the volts with only the power supply built up and got -9.7v instead of -10. I went ahead and stuffed the board anyway. Could this low -10 be due to using an underpowered transformer? I'm using the Amveco TE62045 (10VA, .5A) originally specified in the N.American Parts List thread. Some have suggested it's too small for the job and to instead use part TE62055 (15VA, .6A).

The input and output tx are already installed. (Lundahl in, OEP out.)
The IC1 (TL071) is not installed.
I don't know if they affect the voltages.

Any advice? I would love to hear it. I'm still new to this...

Kato
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 12, 2006, 03:48:05 AM
Voltages can be considered correct if within +/-10% - execpt for the +30V that needs to be +29V or more to ensure correct regulation.

What is interesting for disgnosis is the 0.6V base-emitter drop (difference) on individual transistors.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on June 12, 2006, 08:36:22 AM
Right now I've got a stancor wf30 wired 600:600 from the input to the pads for the oep/lundahl input secondary's.  Should this be wired 2:1?  or 1:2?  I'm really trying to figure out how the lundahl is wired, but something confuses me about the lundahl datasheets, I just can't quite get it.

I could see wiring it 2:1 rather than the 1:1 I have now, as my units seem to have too much gain, especially with the OEP output tx's reversed for 1:2.

Hopefully someone knows offhand?

Thanks,

billy
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on June 12, 2006, 02:56:40 PM
Hi the professionnals

I'm building A dual 1176 with in and out transfos and having  one unit working great and the other not.So I started comparing the units?

Without the fet it's passing audio like the other unit.
With the fet,it needs a lot more input gain even when bypassed.
In ground mode same problem and no compression and the needle doesn't go at 0db.
I have cheked Q12 Q13 Q14 Q15 they are OK

The problem comes from the GR stage because I have a positive voltage moving between 2 and 4,5 instead of -1,4V  at point 7.
At C17 R60 instead of 4,55V Ihave something moving between 1,9 and 4,6.
And the same at point 22 instead of 0V I have smething moving between 1,9V et 4,6V.
At R60 & R62 I have something moving between 17V 25v

What are the moving voltages saying?I'm not enough experienced to understand that sort of bug.
ANY IDEA??
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 13, 2006, 03:30:56 AM
Have you calibrated the unit properly?

If you have a lot of GR just by putting the FET in, this points towards the FET taking off a great deal more than the 1dB that is the target for the q-bias adjustment procedure.

If you have the problem after adjusting properly, try different FET's - and check for soldering, shorts, components, orientation and interwireing as always.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on June 13, 2006, 09:21:11 AM
hi gyraf

yes I've tried to calibrate the bias but it's not reacting as it should.
I have check for soldering, shorts, components, orientation and interwireing at least 3 times each.
I have tried different fets.
And nothing Ican't find the problem :shock:

Except those moving voltages I've no clue.

...
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 13, 2006, 09:46:05 AM
Gachet,

(Could you please resize your avatar to the recommended 60x60 pixels - it takes up a lot of screen-space all through the pages you participate in)

There's nothing to do but check and double-check. possibly try new FET's.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: kato on June 13, 2006, 12:24:16 PM
Quote from: "gyraf"
Voltages can be considered correct if within +/-10% - execpt for the +30V that needs to be +29V or more to ensure correct regulation.
. . .


Hey thanks for the response Jakob! I appreciate it.

So it looks like most of my voltages are within 10%.
The really *big*error is actually a mistake in the checkplot voltage guide I used. I will update my version of this checkplot (one page back) this evening. I'm a little surprised that Synthetic's checkplot was posted almost nine months ago and no one has mentioned this.

The point marked 35.4v is at pin 1 of the 7824 on the UREI schematic. The voltage checkplot points this value to pin 2 - where I'm getting 33.7v which is a lot closer to 35.4v than 30.2v. (only 1.7v off as opposed to 5.2v off. Within 10%.)

The thing that clued me in was looking back at Mnat's wiring guide where he says to expect +30v at pin 2...

(http://nimbleswitch.com/graphs/forums/1176_7824/7824_voltages.jpg)

I called it 6-ish because I don't know what's considered correct - and I'm getting 6.11v there. And 30.2v at the spot Mnats calls +30v.

I think I'm ready to stop obsessing over perfect voltages and get this mofo racked and calibrated!
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on June 14, 2006, 06:06:06 PM
Hi

At last my dual 1176 is fully working and calibrated. :grin:

And I wondered about stereo interconnection.

Is it possible to  connect both fet to channel 1 GR circuit in order to have same ratio attack release and bias on both channels(And disconnect wire 7 of channel 2).
To my mind it's possible in the case of matched fets:same bias voltage.(I have some matched pairs)
Will the different current (caused by the shunt) affect the behaving of the fets?
Second I'd like to feed the channel 1 GR circuit (from R26)with a mix of both channels so the compression will be trigged by both channels.
I'd like to add a variable resistor between the shunt and R26 to calibrate the change of level caused by the stereo  shunt when passing in stereo mode.

Will that working?
Will the unit tolerate that?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 15, 2006, 04:36:55 AM
Gachet,

Look through this thread - and the 1176-meta - and you'll find all info you need about stereo linking.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on June 15, 2006, 08:46:17 AM
Hi
Did I miss, is it better choise to use output transfomer with 1:2 or 2:1 ratio.
We have Jakob project wher is Lundahl wired 2:1 and Mnats who is wired 1:2. Also, we disscused about original 12614 transformer and someone told us transformer have 1:1 ratio.
 :?
Duka
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 15, 2006, 09:09:27 AM
There's no simple answer to that. Depends entirely on the transformer in question and what you want to acheive.

With OEP's I wouldn't go over 1:1 for power reasons, but with the Lundahl LL5402 you can wire it 1:2 if you feel you need the additional gain.

On the other hand, for a sound closest to the original - that is, the rev#F we have in our own studio - use the design as-is. This has lower gain than the original though, but I valued original sonics over original-gain in this adaptation. We never use the units at full-gain anyway.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Gachet on June 15, 2006, 10:56:28 AM
...
Title: All things G1176 - the new "repost" thread.
Post by: kruz on June 15, 2006, 12:33:35 PM
Quote from: "Gachet"
I will never get a a friendly and decent answer in that forum?GRRR

ciao


jakob's answer was very friendly and more then decent.
you just have to do your job instead of asking for a personalized help just for you..
You have an enormeous amount of free knoledge here, you just have to read it. It's DIY!
Title: rack case
Post by: clorax hurd on June 19, 2006, 12:09:00 PM
I'd like to ask, if it's possible to fit this thing into 1U case and if anybody tried it.... or does it have to be 2U? (to me it seems like it would fit in 1U, but i've seen more photos of this unit finished and it was always 2U)
Title: Re: rack case
Post by: kato on June 19, 2006, 01:47:52 PM
Quote from: "clorax hurd"
I'd like to ask, if it's possible to fit this thing into 1U case and if anybody tried it.... or does it have to be 2U? (to me it seems like it would fit in 1U, but i've seen more photos of this unit finished and it was always 2U)


It will fit in 1U if you can find a small enough VU meter.
Title: Re: rack case
Post by: JRE Productions on June 19, 2006, 02:13:30 PM
Quote from: "clorax hurd"
I'd like to ask, if it's possible to fit this thing into 1U case and if anybody tried it.... or does it have to be 2U? (to me it seems like it would fit in 1U, but i've seen more photos of this unit finished and it was always 2U)


I also had it in a 1U rack when I first built mine. But there is only enough room for the knobs of a single unit.

I actually have thought many times about trying to rack everything I build into 1U size cases. I can get more stuff in my racks that way!

Joe
Title: Re: rack case
Post by: clorax hurd on June 20, 2006, 05:28:00 AM
Quote from: "kato"
It will fit in 1U if you can find a small enough VU meter.


It seems that sifam AL19WF would fit into 1U. will try it

JRE Productions: good to hear that! thanks.. .
Title: All things G1176 - the new "repost" thread.
Post by: kato on June 20, 2006, 09:32:08 AM
Hmm, it never occurred to me there was a sifam meter that would fit.

That's a great idea - i've always thought 2U left a lot of empty space for a single channel 1176.

I think I'll try that too.
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 01, 2006, 02:34:03 PM
Hi Everyone,

Well it's been almost 2 years in the making, but i finally had the time to finish my G1176s. I've got some issues with them...maybe. The first thing i checked were all the transistor EBC voltages and they seem to be within norms based on several measurement sets I've viewed here. +30 and -10 are looking good. The unit seems to calibrate properly following Jakob's procedure and the original UREI manual. The unit passes audio and compresses, and all controls seem to do what they should. The unit passes audio in bypass, with the FET in and out of the circuit. The line amp sounds good. In bypass I can get quite a clean signal through it in excess of +3dB VU.

My problem is this. The comp really crushes almost any signal at around 1-2 on the input, and even with the output at max, I can't really get anything above -5 dB VU. I thought I had made a mistake, so I went back and re-read this entire thread and found that a couple people had reported the same behaviors. Kdawg's posts seem to describe my exact situation. Is this normal? the controls don't really respond the same way as the other 1176s I have in the studio. [blue badge, rev F, rev H]

I am using Chef's board built to Jakob's specs, transformer balanced i/o with the romeo trace cut. The first thing I'm going to try is to rewire the output to 1:2 as i am currently running 2:1. This should help my output gain problem. But I'd really like it if the input control would respond like my other 1176. Right now it's really touchy and I feel I can't make adjustments with any precision as I am jockeying the input control between 0.5-2. Also, from a familiarity standpoint I'd like to be able to blindly [deafly?] set it at the good ol' 10 and 2 o'clock as a starting point. I'm just really used to being able to barely tickle the signal with compression at those setting.

I've tried about 4 different matched pairs of FETs and after calibration, the unit reacts the same. BTW, I am interfacing with equipment operating +4dBu @ 600 ohms in and out.

so to summarize:

1. Is what I've described normal?
2. Is there a way to decrease the input sensitivity [input pad, rewire input tranny?] that makes sense and will keep Q1 happy.

thanks for reading.
Title: All things G1176 - the new "repost" thread.
Post by: kato on July 01, 2006, 03:29:25 PM
AL, Might it be something as simple as changing your input pot from a linear pot to a log pot (or maybe the other way around.)

Just a wild guess,  Kato
Good luck!
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 01, 2006, 06:17:52 PM
Hey Kato

Well, i've got a log pot in there now. If I swap it for a linear, I'll be getting more signal at the start of the rotation, which is opposite of where I wanna go...thanks for the idea though.
Title: All things G1176 - the new "repost" thread.
Post by: imo on July 02, 2006, 01:01:20 PM
AL,
I have the same problem. I have rewired the output transormer and it does help with makeup gain, as well as trying a number of different fets. It is the input gain, and the clean headroom when compression is engaged that is the problem. The unit sounds great, the compression sounds great, there is simply too much of it<G>. I have been poking around at ideas to somehow buffer the compression level but nothing has worked so far. I will post any success i have and would appreciate if you make any headway as well
Ian
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 02, 2006, 02:39:39 PM
Thanks for the report. I was looking at the oringial rev F schematic, and was wondering if anyone tried wiring the input as UREI did, with a T bridge attenuator before the transformer. I don't know if the LL1540 would be suitable in this configuration. I can't seem to find the impedances in the data sheet. Does anyone know? Am I blind?
Title: All things G1176 - the new "repost" thread.
Post by: mfdu on July 02, 2006, 09:25:05 PM
got some voltage problems in one of my units.

it's using OEP input and output trannies, everything was measured as it was built.

the problem with unit 4 is signal oscilation at low input levels.  remove the BF245 and it passes clean signal without a problem.

unit 3 is fine (and sounds fantastic compared to the pair of electrically balanced units i built previously)

have tried replacing Q1, Q2, Q3 and Q4, but no improvement.  unfortunately when using my solder wick, the actual PCB tracks came up and i have had to do a couple of point-to-point bridges.  but the voltages remained the same with the replacement components.

i have provided voltages to illustrate :

------------- E ---- B ---- C
Q2 unit 4 :  0 :   0.5 :   1.3
Q2 unit 3 :  0.5  : 0.9  :  1.7

Q3 unit 4 :   0.7 :  1.3 :   17.8
Q3 unit 3  :  1.1 :  1.7 :   11.8

Q4 unit 4 : 17.8 : 17.9 :  29.2
Q4 unit 3 : 11.4 : 11.8 :  29.6

the three pins of the voltage reg (7824) are perfect on both units.  i can't understand where the 17V on Q4 comes from.

(do you require the rest of the voltages?  please advise)

so, my question is this - what feeds voltage to Q2, and where has it gone (there ain't no visable shorts)
also, what could be the cause of the raised voltage at Q4?  i'm guessing they're linked. . .

i'll continue working on it, obviously.  
but if anyone has any tips, i'd love to hear from yerz!

chris.
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 02, 2006, 11:18:29 PM
So for those who are interested, I rewired the input like the original rev F. I found some ganged pots in some routing modules that came from a UA console. They look like the same ones UREI used in rev F and other TX input versions of the 1176. I didn't have a UTC 0-12, the closet thing I had was a hammond 850G, wired as 600:150. I also did the Chef rewire of the output TX so i'm running 1:1 at the output...

Well, it's closer. The input pot makes more sense. The 850 actually sounds pretty damn good. Heavy and soft. It seems to tame the really fast transients that sometimes sneak past at extreme setting. I'm probably going to go for the 1:2 rewire on the output, as I have it at max to get 0 to +3dBVU.

Getting there.
Title: main rotary switch
Post by: Robin Reumers on July 05, 2006, 01:23:19 PM
Hi,

I'm looking for my last parts for my 1176, I'm looking for a main rotary switch, preferably at farnell (because I only need to order there for my last parts), can anyone give a good link with one that should work, because I'm not sure which current rating I need?

Robin
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on July 05, 2006, 01:34:35 PM
I might be totally missing something, but i thought I'd ask anyway...

On both the gyraf parts list and Greg's part list it has a 220p 50v polyester cap...(2 of them) I believe the place on the board is marked 200p.  I assume that this is where it's supposed to go (just trying to make sure I didn't put something else in it's place)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 05, 2006, 03:30:35 PM
yes.
Title: All things G1176 - the new "repost" thread.
Post by: pxpx83 on July 07, 2006, 07:25:08 PM
I skimmed through most of this thread, but I couldn't find the answer I was looking for.

Where is the easiest place to grab power for a power led?  Would it be ok to use the power that lights the VU meter?  I'm using the mnats version of the 1176 pcb.

Thanks!
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on July 07, 2006, 07:53:31 PM
Quote from: "al_p"
So for those who are interested, I rewired the input like the original rev F.


That sounds awesome!  I'm really interested in how you did this.  I have stancor wf30's on mine right now, basically utc a20 clones...  which is the larger core version of the O12, basically.... same hookup options.

Right now it's 600:600, and I think thats a big part of my problem.  But would you mind sharing how you hooked up the pot's?  And how many decks would one need?

I also have some 2, 3, and 4 position greyhills that I could probably use if I can't get a hold of a pot that works, and just kind of have 12 positions.

Anyway, very interested in hearing that someone with the 'too much gain' affliction found an idea.....

I think that if I can hammer these out and get them working how I'd like, I'll probably build the next couple with electronic in lundahl out....  should contrast well with the utc in/oep out that i have now

thanks for sharing

billy
Title: All things G1176 - the new "repost" thread.
Post by: sintech on July 08, 2006, 04:07:41 AM
pxpx83,

 You can use the 36v marked VU LAMP for LED's no problem, Just gang 2-3 (standard 5 mm) in series and add a 1/4 watt 1k resistor also in series on the positive side. LED's will be fine with that voltage but need a current limiting resistor otherwise they smoke!

This could work ok for a Power Led also. If you do a search for "limiting resistor" you'll find all you need.
Title: All things G1176 - the new "repost" thread.
Post by: pxpx83 on July 09, 2006, 12:31:04 PM
Thanks sintech.

I've run into some trouble trying to calibrate my 1176.  I've tried adjusting the q-bias, but turning the trimpot has no effect.  I also tried adjusting the zero adj trimpot, but this has no effect (meter is pegged in GR mode).

I'm suspecting the the two trimpots are at fault.  Ajusting the trimpots fully cw and cww has no effect on the voltage I see on their legs.  The trimpots have 3 legs and i'm only seeing voltage on 2 of the 3 legs (the other 2 trimpots have voltage on all 3)

Any other ideas?
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 10, 2006, 06:55:19 PM
Regarding these clone 1176s and gain, perhaps those of us who have a TON of gain are using Jfets that just happen to have a ton of gain?

Is there a difference between the jfets used in the originals and these we're supposed to be getting?

Have there been incremental improvements in gain on the clone jfets over time?  

I'm going to try going for a lower gain jfet (or pair).
Title: All things G1176 - the new "repost" thread.
Post by: pxpx83 on July 11, 2006, 12:00:05 AM
Found the problem with my 1176 (trimpot for q-bias and zero adj not working).  I used the wrong hole for the spot labeled 18 on mnats version of the pcb.  I have a small trimpot, but I used the hole meant for a large size trimpot.

Just gotta calibrate it and she's done!  :grin:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 11, 2006, 02:01:28 AM
Brad,

The 1176 simply has a ton of gain. They all do. Look at original specs. No error in this.

But if I understand you right, your problem may be that you have too low a threshold - and that has to do with FET cutoff voltage.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 11, 2006, 09:30:59 AM
Hi Jakob,

The overall gain on my unit is fine I think... Actually I generally have the output fully cranked to the max while using the 1176.

The problem I have is low threashold...  (BTW, I have Lundhals on the input and output, PSU voltage is fine, everything has checked out in the past, and I've used it successfully, I've just cracked it open recently to aid with meter issues on an LA2A project and decided to address this input threshold issue)  Here is my calibration technique...

CW output, CCW input, CCW the Qbias pot, CCW the attack, CW the Release, 20:1, Bypass mode.  Protools input of -1dB, 1000Hz, Sine.  Reading the output of the 1176 into protools using that bomb factory meter plugin.  I raise the input pot until i get 0db on the protools meter (if 0 on input is 7 o'clock, i maybe get to 8:30 on the input when the output goes to 0dB!!), turn CW the Qbias pot until the protools meter reads -1dB and then i call it calibrated.  8:30 on the input pot corresponds to my threshold.

Is this correct?  Do I need to do other steps before this? The other calibration procedures calibrate the meter to track and zero the meter, so they are independant correct?  (i do these steps too, btw)

Last night I popped in some of my other FETS that I had left over after matching, the threshold point is completely the same regardless of FET.

If i could get my threshold at like 12 or 1 o'clock, that would be cool.

Do i need to do some voltage probing?

Thanks all!
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 13, 2006, 11:57:44 AM
Hi

I was thinking about this low threshold problem. I was looking at the data sheets for the BF245 and noticed that the A B and C version have different ranges for Vgs and Idss. How do these specs affect the threshold? At all? Sorry my thoery chops aren't good enough to know what this means exactly to the circuit.

I was thinking about ordering a bunch of Bs and Cs, but don't wanna waste time and money. Can anyone comment on this?

thanks
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 13, 2006, 02:07:13 PM
I just took a look at the data sheet:

IDSS drain current VDS = 15 V; VGS = 0

BF245A 2 - 6.5 mA
BF245B 6 - 15 mA
BF245C 12 - 25 mA

Looks like the A version is the tamest of all 3 of these.  I don't think the B and C are going to help us here.
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on July 14, 2006, 11:19:17 AM
I'm building my unit without the input transformer---(I might add it in later)

I thought I read that the parts with a * on them should be left out if building it this way...I just want to be sure I'm correct and also that I'm finding all of the parts.

the ones circled in red?

(http://www.ryanbakerproductions.com/1176.jpg)[/img]
Title: All things G1176 - the new "repost" thread.
Post by: sintech on July 14, 2006, 12:25:35 PM
rbaker,

You're spot on, leave them out for a no input trafo build  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: imo on July 14, 2006, 11:35:18 PM
Just wanted to add again that i am having the same threshold problem and that it is limiting the usability of an otherwise lovely sounding unit. I am using the Lundahl input transformer and have tested a bunch of different FETs to match them. I simply can't get the unit above 10% on the input, and then have to completely open up the units output to get a workable level.
I have done the output mod to double the output, as well as the cut to lessen the ground buzz. This all works great, now if only to find a way to tame the threshold, the unit would be brilliant.
It might be worth it for those of us having the problem to compare what we have, what type of input, balanced or input tran, voltages, etc/
 I am surprised that there is no other way than the FET itself to affect the threshold, but unfortunately my understanding of the circuit isn't comprehensive enough to find another way to address this
Ian
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 15, 2006, 02:10:55 PM
Ian,

Some of us are having the same EXACT issue.  I have mnats' board, Lundahls on the i/o.

I have the same threshold problem, my output is always cranked too!

should we all post some bias voltages?
Title: G1176 low threshold issue
Post by: al_p on July 16, 2006, 08:35:26 PM
Hey Brad, Ian, and anyone else with this issue.

Here are my measurments. The DMM I am using is the cheapest you can get. Measurements above 20V have no decimal place.

       E  B  C

Q2:  0.52 1.01 1.70
Q3:  1.12 1.71 12.25
Q4:  11.68 12.24 30
Q5:  4.32  4.75 28
Q6:  28[+0.57*] 28 14.14
Q7:  29 28 14.14
Q8:  13.55 14.15 30
Q9:  13.46 12.87 0
Q12: 3.86 4.39 14.63
Q13: 14.06 14.63 30
Q14: 2.87 3.43 16.47
Q15: 15.96 16.47 30

*meaning E is +0.57 referenced to B

I built the unit completely to project specs, with some mods. Here's where I'm at.

board: Chef's [with ground cuts]
Input: wired as specified by the rev E schematic using a Hammond 850G
Output: LL5402 wired as 1:2
Output Q: BD135/BD136 with pin re-configuration

The unit sounds great, and calibrates properly.
Title: All things G1176 - the new "repost" thread.
Post by: imo on July 17, 2006, 12:47:42 AM
AL and Brad,
I will try to post some voltages tonight..Thanks for putting them up, will be interesting to see what we get. Also, it seems that all of us are using input transformers. I wonder if anyone had the problem using a balanced unit?
Ian
Title: All things G1176 - the new "repost" thread.
Post by: imo on July 17, 2006, 02:21:41 AM
Here is my info..
I used Lundahl input and output transformers as well as the BD135 and BD136. I have the output transormer mod for 1:2 output and the hitchhiker cut. Everything else is stock and everything has been calibrated
E B C
Q2: .52, 1.04, 1.78
Q3: 1.16, 1.78, 12.23
Q4: 11.6, 12.2, 30.4
Q5: 4.5, 4.9, 28.6
Q6: 29.2, 28.6, 14.7
Q7: 29.8, 29.2, 14.7
Q8: 14.1, 14.7, 30.4
Q9: 14, 13.4, 0
Q12: 4, 4.5, 14.9
Q13: 14.3, 14.9, 30.4
Q14: 2.9, 3.4, 17.3
Q15: 16.8, 17.3, 30.4
Title: All things G1176 - the new "repost" thread.
Post by: al_p on July 17, 2006, 09:50:34 AM
Looks like we're in the ball park with each other, and other measurements I've seen. Nothing obviously wacky there.

Has anyone tried 2N5457s for the FETs?
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 17, 2006, 03:10:13 PM
just wanna throw an idea out there that just popped into my mind.

we're all using 10k(If i remember right) Log pots on the input.  what if that log characteristic is incorrect....

take a look at this:
http://www.efunda.com/math/exp_log/images/exp_log_plot.gif

seems like we have a log characteristic (in blue) , where we may want the exponential characteristic (in red).  Maybe this is a clue...

just thinking...

i'll get some voltages posted in a day or so.
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on July 24, 2006, 10:11:32 PM
Hi all

I'm just starting my first DIY project that isn't a kit - a G1176 (which is why I'm here...)  I was hoping that I'd able to build the thing without needing to pester anyone, given the mountains of info on this site posted by the wonderful people here, and on the internet, and otherwise figure it out as I go.

Almost... :grin:

I'm currently waiting on some caps from Digikey, and in the meantime have drilled my front and back panels and am in the process of doing some off-PCB wiring.  

I want to ask a simple question regarding the fused IEC connector.  I've searched away on this and found a lot of info, but nothing bang on point.  The IEC looks like this:

(http://www.altronics.com.au/images/prod/P/P8325.gif)

and a drawing of it looks like this:

(http://www.altronics.com.au/graphics/etc/P8325.jpg)

From the bottom drawing, there are three lugs, one in the top middle (which I know is the ground - it has a "G" next to it) and two on the left.  The top-left has a "N" next to it, so I'm sure it's the neutral.  The lug below it, by process of elimination, should be the live.  However, the "L" for live is on the right-hand side, where there are no lugs.

My belief (but I'm not certain) is that the live lug is on the left as the live pin connects to one (right) side of the fuse, and reaches the lug on the other side of the fuse on the left - hence the live lug being on the left, along with the neutral lug.

Is this right?  Given I'm learning about mains voltages here, I'd prefer to ask dumb questions than get it wrong - there's more at stake than a $2.50 IEC  :idea:  :shock:  :idea:

While I'm at it - my torroid has two wires comprising the primary - brown and black.  On the diagram on the side of the torroid, the brown is on the top and the black is on the bottom.  Should brown go to live and black to neutral?

Apologies again for asking the obvious.

Chris
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 24, 2006, 11:04:08 PM
Hey Guys,
After long last, I've checked my voltages and mine are pretty much in line with both of yours.  

Still battling!
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 24, 2006, 11:07:24 PM
Not to leave you out Chris...

But yes, it looks like the fuse is right after the Live terminal on the plug as it should be.  You should get a multimeter and make sure.  You will need a multimeter for this project, and basically for getting thru life, so get one.

You always want to switch and fuse on the Live lead.  Hardcore dudes switch on both the live and neutral, just to circumvent any idiot housewiring.

good luck.
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on July 24, 2006, 11:23:48 PM
Thanks Brad - nice to have it confirmed

Yeah, I have a multimeter - just wanted to check before I start making an idiot of myself...

Cheers
Chris
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 25, 2006, 09:25:03 AM
to my pals who are having input threshold problems with input trannies...

I'm going to give a try for rewiring my input tranny for 2:1

like here:  http://www.groupdiy.com/index.php?topic=15543&highlight=lundahl+input+1176


Quote
PRR recommended a 2:1 ratio for the input transformer back when we were discussing it some time ago. 2:1 is what the original UREI units used as well.  
Title: All things G1176 - the new "repost" thread.
Post by: imo on July 25, 2006, 12:02:55 PM
Brad,
Please post results when you do.
Ian
Title: Meter not steady at zero point and ratio problems.
Post by: mdrenthen on July 27, 2006, 03:29:42 PM
Hello I'm new here and the proud owner of a DIY 1176 with Mnats boards.
I don't have the time to read al the threads, so if I ask a quistion thats already been asked, i'm sorry.

Here's my first problem.
With no signal on the input and the meterswitch in GR mode, the meter walks slowly around the zero point and never is steady, not even after an hour.
Adjusting it with the zero pot. does not help.(onley for a minute)

Second problem.
With the same singal, input and output settings my 1176 shows the same gain reduction in all the ratio settings.
I also checked this on a external output meter.
Maybe the 1176 react in a other way than a 'normal' compressor?

Please help me out with this one....thanks....many thanks..

Michel
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 28, 2006, 03:36:19 AM
For the meter moving around slightly, try cleaning the pcb board area around the meter fet and related circuits. It's very high impedance, so even a little dirt can disturb it.


Quote
With the same singal, input and output settings my 1176 shows the same gain reduction in all the ratio settings.
I also checked this on a external output meter.


Normal, and has been discussed before. If you look at the schematic, you'll see that the threshold is altered with ratio to acheive this. But if you set it to just 1dB of GR, the ratios should give you different results.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Gustav on July 28, 2006, 06:29:00 AM
first of all - any way to search within this thread? (I read through a lot, but not everything to look for my problem)

Second. - I have a G1176 that seems to be fine electronicly, and the compression seems to work like it should - however - it only outputs hi-end. I have tried running it both balanced and unbalanced pin3-ground shorted, with no change.

Would it be totally idiotic to try switching the lundahls? Any other suggestions?

Gustav
Title: All things G1176 - the new "repost" thread.
Post by: Gustav on July 28, 2006, 07:16:45 AM
Quote from: "gyraf"
Andre,

Look for a balancing issue on cabling. I'm pretty sure that's it.

Jakob E.


Found an answer to a similar problem on page 46....Ill check up on it

Gustav
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 28, 2006, 08:00:57 AM
Gustav,

Yes, searching is becoming a bit hard within the posts. There is a good, but not simple way to search in long forum threads:

(from meta-meta)

Quote
-----
About searching:
As you have probably already found, the integrated forum search-engine can be a pain to use when searching for information in some of the long-long threads. Mike (user insideout) has come up with an elegant solution to this - involving the browser "Firefox" and a plugin called "ScrapBook". This really enhances searches over many-many pages, like the giant error-fixing threads.

Mike has put together an easy-to-follow howto, found at: http://mikeinak.googlepages.com/home


And yes, I'm pretty sure that you have a balancing issue. Make sure that both your + and - outputs has connection to the output transformer secondaries, and make sure to connect - to ground (on both input and output) when interfacing to unbalanced stuff like your new patchbay :razz:

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mdrenthen on July 28, 2006, 08:12:10 AM
Quote from: "gyraf"
For the meter moving around slightly, try cleaning the pcb board area around the meter fet and related circuits. It's very high impedance, so even a little dirt can disturb it.


Ok I'll try that.
Can it be that some of my components are of he wrong type?
I use BC107MC instead of the BC107A/B/C
And for the TL071 I use an TL071CN version.
The rest is the same as dicripted in the partlisting.


Quote
Normal, and has been discussed before. If you look at the schematic, you'll see that the threshold is altered with ratio to acheive this. But if you set it to just 1dB of GR, the ratios should give you different results.


The gain reduction stays the same at all ratio settings.
The meter is moving towards the right corner when switching the ratio and than returns. I checked the wires and they are all connected to the wright pads.

Michel
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 28, 2006, 08:16:33 AM
Quote from: "mdrenthen"

Can it be that some of my components are of he wrong type?
I use BC107MC instead of the BC107A/B/C
And for the TL071 I use an TL071CN version.
The rest is the same as dicripted in the partlisting.


..Shouldn't be a problem at all..


Quote from: "mdrenthen"

The meter is moving towards the right corner when switching the ratio and than returns. I checked the wires and they are all connected to the wright pads.


..It's normal (also on originals) that meter misbehaves when you operate the ratio switch..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mdrenthen on July 28, 2006, 08:44:23 AM
Quote
Normal, and has been discussed before. If you look at the schematic, you'll see that the threshold is altered with ratio to acheive this. But if you set it to just 1dB of GR, the ratios should give you different results.


I tried again but the gain reduction stays the same at every ratio setting.
I put a signal to the input, turn the input level on the 1176 up adn stop at a GR of app. 1 dB.(at ratio 1:4)
Then I switch to ratio 1:8 and 1:12 and 1:20 and the gain reduction stays arround 1 dB.
That should be more at a higher ratio..or am I mistaking?
If yes.....what could be wrong then??!!

Quote
..It's normal (also on originals) that meter misbehaves when you operate the ratio switch..

 Thats a relieve then. :grin:

Michel
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 28, 2006, 09:37:27 AM
You need to make up a complete input/output level chart for the different ratios in order to verify that they work correctly - simple tests are probably not revealing enough.

If it turns out ratio'ing the same on all settings, the only place where you could have gotten this wrong is at the resistor-ladder divider at the ratio switch - which you may want to double-check for solder blobs and right wireing and resistor values.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: mdrenthen on July 28, 2006, 10:16:43 AM
Quote from: "gyraf"
You need to make up a complete input/output level chart for the different ratios in order to verify that they work correctly - simple tests are probably not revealing enough.

If it turns out ratio'ing the same on all settings, the only place where you could have gotten this wrong is at the resistor-ladder divider at the ratio switch - which you may want to double-check for solder blobs and right wireing and resistor values.

Jakob E.


I am testing it with some protools tracks with different ratio settings and in/out settings, and now I understand the 1176 a bit more.
It's indeed not like other compressors...it's better. :wink:

Thanks Jakob, for helping me out so far.
Title: All things G1176 - the new "repost" thread.
Post by: bradb on July 31, 2006, 02:14:21 PM
I did some brainstorming this weekend on the input power transformer issue.  I don't think the 1:1 to 2:1 is going to help.

Think about it like this.

If we drop a signal that input into the 1176 by 3dB (cutting it in half, basically 1:1 to 2:1) does that change the threshold?  No.

The input threshold is a function of the FETs, not the input tranny.


Jakob, when I swapped out different FETs to try to raise my input threshold, all of them were basically the same.  Do you think we need to pursue different FETs or different biasing?  Any ideas we can pursue?

thanks!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 01, 2006, 02:36:07 AM
The BF245A should be in the right area.

Are you absolutely sure that your input level potentiometer is the correct type, i.e. a log one, not a lin? A linear pot at the input level would behave like you describe.

Jakob E.

(ps: ½voltage is -6dB)
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 01, 2006, 09:50:38 AM
Jakob,

I think I posted somewhere on prodigy about the Log / lin pot issue (ok just found it).  I know I have an audio pot in my 1176, BUT what if I and everyone else with this problem bought audio pots with the WRONG characteristic.

take a look at this:
http://www.efunda.com/math/exp_log/images/exp_log_plot.gif

Sounds crazy, I know, but if you have an exponential characteristic instead of a log characteristic maybe you end up with this "you must have a linear pot in there" problem.

I'll try to get some time to investigate this.

EDIT: by the way, here is the input pot I ordered (from Mouser.com)


Mouser P/N      Alpha P/N
31VJ401-F       RV24AF-10-15R1-A10K     Alpha (Taiwan)     Audio 10K
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 01, 2006, 01:19:23 PM
Taiwan-Alpha "A10K" should be the right type!

To check if a pot is Log or Lin:

Try measuring pot resistance from viper to either end with the pot in (more or less) centre position - if it's a log, there should be a big difference in resistance, if it's a lin, the resistances will be approximately the same..

Jakob E.
Title: low threshold progress
Post by: al_p on August 01, 2006, 02:29:09 PM
Hey Brad, Ian and others with this problem,

I tried using the 2N5457 in place of the BF245. It's what Purple Audio is using in theirs, and what was used the original...

I built a dual unit, so I kept the BF245 in CH 1, and popped the 2N5457s in CH 2. After matching and calibration I'm getting about half as much compression as the channel with BF245, with the same input settings. Promising. It's reacting much more like I am used to.

Jakob, do you have any comments on using this FET in your circuit?

So that's the good news. the bad news is the my input arrangement isn't quite right. The ganged pots I pulled from those UA routing modules aren't quite the right values.

Does anyone know any details of the original dual ganged 600 ohm T bridge attenuator? What makes it so special? Can you not just use a dual 600 ohm audio taper pot with tight specs? I was thinking about ordering a couple from Precision.

Also, a question for those who have built a dual unit. I have a slight noise problem which seems like an interaction between the 2 channels. If I listen to channel 1 cranked, I have a little hum. If I disconnect the output XLR of channel 2, the hum clears up same result with this test on channel 2. The same thing happens if I disconnect the AC power to the other channel. I have the secondary of the power TX paralleled to both channels.  

 thanks for any input.
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 01, 2006, 02:39:01 PM
I built the "SL1176", which is Eddie Cilleti's and Scott Liebers version of the 1176. They use the 5457 as well, and i am able to get quite a bit more headroom with it. The specs don't look that different, but who knows.
I have an audio 10k input as well, but i am going to measure just to be sure there isn't anything funky going on
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 01, 2006, 04:40:08 PM
Al,
Thanks for pursuing this, this does sound promising:

You say it has half as much compression as the BF245 channel.  What do you mean exactly, like the compression ratio is different, or are you talking about the input threshold?  

If 0 on input is 7 o'clock, where is the threshold point with these new FETs?

Regarding the 600 Ohm T attenuator.  All I know is that originally it was installed before the transformer and always presented a 600 ohm input impedance.  

Thanks!
bb
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 01, 2006, 05:41:24 PM
I measured the input pot and found that at about 75% of the way clockwise the resistance starts to lessen. It gets to about 2.7k and then goes back down to about 1.2k with the knob turned fully clockwise. The 2 10k resistors on the output of the input transformer are measuring a bit above 700r a piece in circuit. Does this sound funky?
 I am curious to know how you guys wired your input section. I used the Lundahl 1540, and used Mnats wiring guide in hooking it up.
From the input pot (10KA):
clockwise tab goes to pin*1( output of input transformer)
wiper goes to pin 2 of the input gain
couterclockwise tab ties the shield of both the clockwise and wiper tabs together, and goes to pin 3 of the input gain
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 01, 2006, 05:41:38 PM
I measured the input pot and found that at about 75% of the way clockwise the resistance starts to lessen. It gets to about 2.7k and then goes back down to about 1.2k with the knob turned fully clockwise. The 2 10k resistors on the output of the input transformer are measuring a bit above 700r a piece in circuit. Does this sound funky?
 I am curious to know how you guys wired your input section. I used the Lundahl 1540, and used Mnats wiring guide in hooking it up.
From the input pot (10KA):
clockwise tab goes to pin*1( output of input transformer)
wiper goes to pin 2 of the input gain
couterclockwise tab ties the shield of both the clockwise and wiper tabs together, and goes to pin 3 of the input gain

Ian
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 01, 2006, 06:51:19 PM
Brad,

So I strapped the compressor across a pair of busses, applied a 1k tone, and with matched knob positions the 5457 channel was showing 3 dB of gain reduction, while the 245 channel was showing just about 6 dB. I know it's kind of an un-scientific way of examining this, but practical application is what I'm building this for. With program material the difference was more sublte, but noticable for sure.
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 01, 2006, 11:11:46 PM
imo, that sounds like it makes sense, as you go clockwise resistance should decrease.  on a side note, i think the 10k resistors should be 12k according to lundahl.


Al, did you match both of the new FETs so that the meter tracks?  Did you observe this difference in compression on the unit's meters or on the input to a DAW or board or whatever?

are we getting close?


sorry i havent been contributing, i'll have some time this weekend.
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 02, 2006, 02:54:04 AM
I wonder if you can make earings out of the 245's>? I've got a lot of them.
I popped one in and had only a couple of moments, but it did seem a little lighter on the compression than the 245..Need for time, must have more time..
Thanks for the tip on the 1540. I looked at the pinout on the specs, but didn't notice the resistance change. I will try a couple of 12's
Ian
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 02, 2006, 04:21:14 AM
This is a bit wierd - my original tests for compatible FET's showed that the BF245A's (at least the three different samples that I got hold on) to be spot-on compared to our Real1176'es.

Could it be sloppy marking, or different manufacturing process messing up? I know too little about real-life FET behaviour to be sure of where this problem comes from..

For now, I don't really know how to get around this - obviously we've run into some non-trivial component tolerances and/or specifications.

A possible simple solution could be to reduce sidechain signal feed level - that will have the same effect as raising the threshold.

We can do this by lowering signal level at the first half of the ratio switch - this part adjusts threshold to match up with different ratios:

Look at the schematic and layout - find R26 - which is 56K - connected to Point15 and the top of the "out level" pot. You will find it on the ratio switch subboard.

If you increase the value of this, you increase the ratio of the voltage divider, and in effect reduce the level going to the rectifier amplifier circuits.

Try with a value of say 100K or 220K in stead of this 56K - or better, try soldering in a 470K trimpot in series with the 56k, which would allow you to find and set a threshold value that suits you. (Maybe it's time for an upgrade of this old-old design - adding a front-panel control for variable threshold?  :grin: )

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: al_p on August 02, 2006, 01:36:46 PM
Thanks for the comments Jakob. I'll investigate this, but I'm pretty happy with where my 5457 channel is at right now.

Roger, just to recap, I agree, this compressor sounds GREAT. I spared no expense on components and I think it might even outperform the other 1176s I have. My problems were getting the controls to respond the way I am used to. It was really disorienting before I started all my jiggering, but I'm almost there.
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 02, 2006, 03:37:29 PM
amen..It is such a gift to be able to build units of this quality, and i agree that  they are really beautiful sounding. There are so many resources and people with knowledge that are willing to share their design knowledge.
It has really helped me as well to understand a lot of the other gear that i have been using in my studio, as well as the general sonics of a lot of things that i have just taken for granted for years.
Cheers Jakob
Title: mnats psu for dual 1176
Post by: jlearman on August 03, 2006, 01:20:35 PM
Hey gents, I'm just a few steps from getting the mnats boards of my dual 1176 stuffed.  I have some noobie questions about parts & part numbers...  

first of all, on the mnats psu, does anyone know what those thingys for attaching the input/output wires are called (i.e. wire from toroid & wire to main board)?  Even better, does anyone know a part number for mouser/digikey?

Also...I don't think mnats has a diagram for the power supply, so I don't know which cables to attach where.  The wires from my toroid are different colors than the one in his picture, and since I don't even know what the hell a toroid does, it's kinda hard to figure out.

Big thanks for entertaining my questions guys...here's a picture of the psu for reference:

(http://www.geocities.com/m_natsume/images/psu_full.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: mnats on August 03, 2006, 04:15:21 PM
Quote
does anyone know what those thingys for attaching the input/output wires are called (i.e. wire from toroid & wire to main board)? Even better, does anyone know a part number for mouser/digikey?

Here they are just called PCB Mount Screw Terminals or Terminal Blocks. A quick scan of the Mouser catalog turned up this: 571-2828373 but check out the specs before ordering it to make sure it will clear the components around it. You could also simply solder the wires to the pads as usual by passing them through the holes in the top and soldering them underneath.

Put some heat sinks on the voltage regulators!

Quote
Also...I don't think mnats has a diagram for the power supply, so I don't know which cables to attach where.


The pads that are marked AC-CT-AC go to the transformer secondary. The ones that are marked V+ and V- are the Positive and Negative DC pads that power the main boards. There is a Ground pad in between the positive and negative that isn't marked.

Quote
The wires from my toroid are different colors than the one in his picture, and since I don't even know what the hell a toroid does, it's kinda hard to figure out.

It's been discussed many times - do a search (hint: I have linked to one explanation on my wiring page). There doesn't seem to be any standard for wire colors on the transformer secondary so you will have to learn to read the symbol and possibly connect two wires to make the center tap.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 04, 2006, 07:34:57 AM
:thumb:
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 04, 2006, 03:03:33 PM
I'm finally getting around to finishing my 1176 which has been sitting for almost 2 months untouched.  :(

I have 2 questions.  on the gyraf site it says to make sure the center tap of the power transformer is connected to ground---I assume that only means via the 0v on the board, not the chassis ground or iec ground?  input xlr ground goes to chassis then to iec and that's it right?

secondly I have to hookup the lamp for my sifam meter.

I've done some reading and it looks like the lamp connection is giving 36v.  I know there's the gyrad board and the mnats and most of them seemed to be talking about mnats, I'm using gyraf.  Still 36v?

Can someone check my math? this is new to me.  

12 volt lamp,  1.2 watts. (.1 amps)

I need a 24 volt drop

resistance is = 24v/.1A = 240ohms?

power = 240 x .1 x .1 = 2.4 watts?

So I assume I need a 240 ohm 2.4 watt or greater resistor.  The place I'd buy it lists a 220 ohm 3 watt, or a 300 ohm 5 watt.  Should I shoot for a higher resistance to keep the light burning longer or does the 22o ohm sound ok?

Thanks
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 04, 2006, 06:08:15 PM
YOur math is right. I would go with the bigger resistance and the longer bulb life. It worked great for me
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 06, 2006, 12:30:10 PM
Ok,

First of all, thank you to Jakob and Mnats, a very experienced, compressor maniac, engineer friend of mine prefers my 1176 to his reissue 1176.  Thanks for making this project available to us here and for consulting and troubleshooting with us.

Jakob, I'm trying your idea of replacing R26 and its definitly working.  After trying different values, I found that 760K is about right for me...

HOWEVER, the ratios are messed up, I'm doing the meter track calibration and I get a higher compression now at lower ratios.  20:1 is the lightest compression.  I verified this also by looking at input and output in PT metering.

I am now sticking with a R26 of 270k.  I thought I was getting a bit extreme, but still my ratios are screwy.  Maybe try 100k?  

If we change the input to the voltage divider, don't we also need to change every other resistor in that circuit?
Title: optional input transformer
Post by: jlearman on August 08, 2006, 02:06:53 PM
Since mnat's boards have the two optional inputs, is it possible to install a switch that toggles the input from the transformer input to the electronically balanced input?  Similarly...if I'm going through the transformer input, and I install the parts in the "optional" section...will it screw anything up?  I'm assuming that if you go into the transformer input, that the entire path of the other input is bypassed....

not sure if that makes any sense...but I'm curious if anyone has done something like this.

thanks,
joe
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 09, 2006, 03:08:38 AM
Brad,

Yes, I see that now.

Unfortunately I do not have a G1176 around to experiment on.

A better approach will probably be to install a 100K trimmer pot at the input to the sidechain, as a simple attenuator/voltage-divider (from the top of the output level pot at the ratio subboard) and keep the 56k as-is.

If you try this, please let us know how it turns out!

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 09, 2006, 09:50:26 AM
Jakob,

Something like this?

(http://i38.photobucket.com/albums/e124/banksbrad/attn.jpg)


i'll post results as soon as its complete.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 09, 2006, 09:53:16 AM
Nope - rather input (from out level pot's top) to top of the trimmer pot, output from viper (to the 56K), bottom to ground.

Ya'know - a standard attenuator - like the output level pot..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Dr nEon on August 09, 2006, 12:58:11 PM
Hi All!

 Very quick question...

 A have been given a couple of panel mount leds (satin 14mm red) that rs sells . They are rated 24-36v dc , 17mA , and look ideal for power indicators on my G1176s which I've almost finished.

 Question is, would it be best  to feed one of them from just after the bridge rectifier , before the voltage regulator?
 
I am already using up the vu lamp feed for the meter leds , so I can't see any other place where I could feed this new indicator from..

 I assume this type of indicator has dropping resistor built in,and that I shouldn't need to put anything else in series with it ?

Many Thanks!

nEon x
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 09, 2006, 01:50:52 PM
Jakob,
Thanks, will try it ASAP!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 10, 2006, 06:02:14 AM
Quote
Question is, would it be best to feed one of them from just after the bridge rectifier , before the voltage regulator?


Take it before regulator.


Quote
I assume this type of indicator has dropping resistor built in,and that I shouldn't need to put anything else in series with it ?


If the mentioned specs are correct, it's a drop-in. But you never know - consult data sheets for the item..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Dr nEon on August 10, 2006, 06:08:06 AM
Ok will do!

 Thanks very much , Jakob! :thumb:

 nEon.
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 10, 2006, 05:38:33 PM
I just "fired" up my 1176 for the first time.  I didn't connect the lamp yet, and the 220ohm resistor right after the lamp connection started smoking a tiny bit and turned partially black.

I ASSume that the issue is related, or would it be something else causing this?
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 10, 2006, 11:04:12 PM
The 100k pot works well and allows you to completely change your threshold, its a very nice fix... thanks jakob.  I recommend that you guys try it out.

I may have spoken too soon on my ratios and changing the 56k resistor... When I turn the 100K pot such that it is essentially out of the circut (0 ohms between input and wiper) I'm notice that my ratios are still reversed!

I checked all the resistors on the ratio board and they are correct.

Maybe I have my stops reversed in my lorlin switch, is there a common stupid mistake that I've made?

thanks everyone
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 11, 2006, 03:19:16 AM
Quote from: "rbaker"
I just "fired" up my 1176 for the first time.  I didn't connect the lamp yet, and the 220ohm resistor right after the lamp connection started smoking a tiny bit and turned partially black.



Update:

I connected the vu lamp, replaced the 220 ohm resistor (tested the one I took out and it was the right impedance) and triple checked for solder blobs.  

Fired it up again and the same 220 ohm resistor (a new one) started smoking and turned black.  The light on the vu meter does work now.

I quickly turned it off---where should I start?  Replacing the 7824?  Is it possible I wired the torroid incorrectly?
Title: Re: optional input transformer
Post by: mnats on August 11, 2006, 04:29:24 AM
Quote
Since mnat's boards have the two optional inputs

Don't know how many times I've said it but my boards are based substantially on Jakob's original design. He originally designed them with both electronically balanced and transformer inputs.

When I did my redesign I added footprints for the optional OEP transformer. Hope that clears things up. Credit where credit is due!
Quote
...is it possible to install a switch that toggles the input from the transformer input to the electronically balanced input?
...not sure if that makes any sense...but I'm curious if anyone has done something like this.

There isn't much that hasn't been tried:

http://www.groupdiy.com/index.php?topic=646&start=765

If you wanted to go further and use the same XLR input jacks for both transfomer and transformerless you would need to switch before the input circuit as well. Might be worth using some relays if you wanted to make this a permanent part of your build.
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 11, 2006, 03:31:39 PM
I just did a page by page search about the ratios and found that the solution to my problem, the ratio switch also changes the threshold.

edit: see here..

(http://i38.photobucket.com/albums/e124/banksbrad/1176_ratio.jpg)


so looks like I'm set... imo and Al, try the 100K pot, its totally legit.
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 11, 2006, 03:52:22 PM
Quote from: "rbaker"
I'm building my unit without the input transformer---(I might add it in later)

I thought I read that the parts with a * on them should be left out if building it this way...I just want to be sure I'm correct and also that I'm finding all of the parts.

the ones circled in red?

(http://www.ryanbakerproductions.com/1176.jpg)[/img]


I think I found the problem...I had posted a similar picture a while back, asking if I had all of the ** parts to remove for electronically balanced input.  I missed the the 1000u cap to the right.  Someone posted saying I had them all, and I moved on.

Anyway I updated the picture, so that if anyone else sees it, it's now correct.

I'm going to remove it right now, replace the charred resistor, and give it another go.
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 11, 2006, 06:03:42 PM
ok well, I got that cap out and replaced it but the resistor is still smoking.  I have triple checked for solder mistakes, cap orientation, wrong placement etc.  

I tested the voltage off the torroid and between the two it's 48 vac

Any other things I can check?
Title: All things G1176 - the new "repost" thread.
Post by: sintech on August 11, 2006, 06:26:11 PM
Maybe post some Hi resolution pics of your Pcb/unit, see if someone can spot what's going on.
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 11, 2006, 10:00:26 PM
I'm making some progress.  I had a feeling it had to do with th 1watt 1k1 resistor.  I knew I had tried verifying them but they weren't really reading an impedance (it was coming out at like 2 ohms)  I figured it just had to do with my cheap dmm and it being a heavier resistor.

Anyway I bought some new 1k1 1 watt resistors that I was able to test and verify.

I put it in and the 220r resistor no longer burns.

BUT now the 100r resistor right next to q7 burns.  I was able to take some measurements by turning it on and off quickly.  It seems that anywhere I'm supposed to have 30 volts, I have about 26.  

for example, the 7824 has 28v/5/26

I tried to buy a new 7824 but I'm having trouble finding them locally.  I have replacement bd517/bd518's available.

Aside fromt that I don't know where to start, I guess I'll just start replacing resistors on their way down to that.  Any ideas, especially what could be throwing off my voltages?
Title: All things G1176 - the new "repost" thread.
Post by: imo on August 12, 2006, 01:03:08 AM
Brad,
Congrats! I will check it out as soon as i have a few moments home, out on a short tour-
I didn't totally understand your comment about the ratios? Was the changing of the 56K messing with them or did you not know that the threshold changed  with ratios?
BTW, i just completed a stereo balanced input. I have a lot more room on that unit than on the input transformer model. They both sound amazing though
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 12, 2006, 03:20:54 PM
imo,

basically when you input a fixed tone and cycle thru the ratios switch you instantly think that your unit is screwy because you get higher GR at lower ratios... but the threshold is actually moving too.

I think changing the 56k resistor will change your ratio, but honestly the 100k pot is really nice and adjustable.
Title: All things G1176 - the new "repost" thread.
Post by: Dr nEon on August 14, 2006, 01:07:41 PM
Hi!

 Question regearding G1176 power transformer that I cant find answered anywhere else:

 The original gyraf parts list calls for a 2x24v 500mA tx. (24VA) , but I have seen that people are using 30VA for dual G1176 builds.

 I can obtain 2x25v tx rated at either 15VA or 30VA  .

 I read in another thread that the G1176 current draw is 37.4mA

 My additional items are:
                            vu illuminaton leds = 20mA
                            and "power on" led = 17mA

 so, if my total current is around 75mA ,  does this mean I can use the 15VA transformer to power a single unit?
 
Or am I undersizing?

Cheers nEon.
Title: All things G1176 - the new "repost" thread.
Post by: sintech on August 14, 2006, 03:03:37 PM
Hi nEon, I'm using 2x25v 30VA in my G1176 units, Farnell part number :9531750

If I was making a Dual I'd pop two of these in... eleven quid! you can't go wrong!
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 15, 2006, 04:12:33 AM
bradb,

Thanks for the feedback! I'll try to include this potential fix in a future upgrade!

rbaker,

Seems that something is drawing tooo much current from the supply rails.

You probably have a pcb trace short or a wrongly-mounted or burnt-out transistor somewhere.

Make sure that you have the bd517/bd518's in the right way around!

The only way I can think of to find errors like this is trying to cut (and later resolder!) the +30V supply trace at various locations to try to isolate where the over-current is taken..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Dr nEon on August 15, 2006, 05:12:51 AM
Cheers Sintech .

 Thanks for the info.

 I am still keen to know if anyone has used a 15VA without problems .

 If my above calculation is correct , 15VA should be fine , but I fear(as usual!) I may be missing something.

 One of the advantages of a 15VA tx would be the smaller diameter . I am mounting it vertically at the back of a 2u case , and i'd like as much clearance as possible , for safety's sake .

Thanx again,

nEon.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 15, 2006, 05:19:37 AM
Neon,

A 15VA power transformer should be alright for the G1176..
Title: All things G1176 - the new "repost" thread.
Post by: Dr nEon on August 15, 2006, 06:45:31 AM
Thanks Jakob. :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: bradb on August 15, 2006, 10:24:41 AM
The 100k pot adjustable threshold is really cool because now I have tons of usable gain in the G1176.  

a great deal more gain staging can be performed.  Thanks Jakob
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 15, 2006, 01:52:49 PM
Quote from: "gyraf"

rbaker,

Seems that something is drawing tooo much current from the supply rails.

You probably have a pcb trace short or a wrongly-mounted or burnt-out transistor somewhere.

Make sure that you have the bd517/bd518's in the right way around!

The only way I can think of to find errors like this is trying to cut (and later resolder!) the +30V supply trace at various locations to try to isolate where the over-current is taken..

Jakob E.

Yeah I figured a large part of it out--- I had bent the pins of the bd135/bd136 but somehow in the last step I put them in backwards.  I ordered an extra pair, put them in right and things were working.  Then I was measuring voltages on one of them and the probe accidently shorted 2 of the pins---it seems to be dead now so I ordered some more.

Anyway nothing was burning and most of my voltages appeared to be correct.  Even though I was tearing my hair out, I learned a lot about following schematics and tracing back why things weren't working, so I'm glad I had all these issues.  :)
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 20, 2006, 09:09:54 AM
Quote from: "rbaker"
I'm building my unit without the input transformer---(I might add it in later)

I thought I read that the parts with a * on them should be left out if building it this way...I just want to be sure I'm correct and also that I'm finding all of the parts.

the ones circled in red?

(http://www.ryanbakerproductions.com/1176.jpg)[/img]


Hi all,

I've spent the weekend building my G1176 (using the Mnats board).  It's my first serious project, and I think I've got most of the way there in one hit.

I'm using the OEP 262A2E for both input and output.  I've got some issues/questions that I could do with some help on, so I'll describe what I've got so far:

1. The unit passes audio quite nicely.  The input and output pots work.
2. I've checked the voltages  at each transistor, and they were roughly as posted on the schematic. So far, so good.
3. I haven't calibrated the unit yet.  Do I need an oscilloscope to do this, or is there a workaround that will get me there?
4. I when I put a signal through, and put the meter in Vu mode, the meter generally follows the strength of the signal, but never gets very "high" (i.e close to 0Vu)
5. I can't tell, aurally, whether I'm getting any compression.  I can't discern a difference between the bypassed signal, 4:1 or 20:1.  This has been the case putting in guitar, bass, or vocals (I haven't been able to trial it with anything else yet).
6. My doubts about compression are amplified by the fact that I can't discern the attack and release pots affecting the sound at all.
7. I just thought of this - my wires connecting 18 & 21 from the main board to the ratio board are the same colour.  I've shrink wrapped those wires together, and foolishly didn't mark which was which before doing so.  So now there is no way of telling which is which.  When I was wiring up the board I checked for resistance at both ends of both wires, to identify which was which, and was pretty confident I had it right.  If I have them the wrong way around (i.e 18 on the main board is connected to 21 on the ratio board and vice versa), would it give me the symptoms referred to above (sound ok but no compression)?  
8. I've installed the two 10k resistors circled in red in the above picture, but not the other parts circled in red.  Do I take it I should I should install them?

I'm hoping that all I need to complete the job is calibration, but the lack of discernable compression makes me doubt that.  Something is not quite right, and it might be 7 or 8 above.

Any thoughts?

BTW, a big thankyou or Jakob for making this available.  Finding his site has given my interest in music (which was waning) a jump start.  Thanks also to Mnats for the boards, and to all those guys who have posted in this thread, asking the questions I undoubtedly would have along the way  :cool:

PS Sorry for the long post.  I thought I get it all out there in one hit!
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on August 20, 2006, 02:36:17 PM
If you're using the input transformer you need the other parts as well, or at least when you're using the luhndal transformer.  I can't imagine it's any different with the oep.  As far as the cap on the far right, that's not a cap for the input section and doesn't follow the same *** rules as the others---jakob said it's optional (regardless of input method) but that it really should be there.

I should probably delete that file to avoid any confusion about it.
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 21, 2006, 02:58:32 AM
Don't delete it - it alerted me to a possible issue I hadn't previously contemplated.  Every little bit helps!

Methinks I'll return to reading this post (again) to see if anything jumps out at me.
Title: All things G1176 - the new "repost" thread.
Post by: mnats on August 21, 2006, 03:35:35 AM
Quote
7. I just thought of this - my wires connecting 18 & 21 from the main board to the ratio board are the same colour.

I'm sure it's been covered before but it is worth mentioning again - my boards have two possible connections for pad 18 depeding on what size trimmer you used for R81. The later revisions have an <18> pointing to the two possible holes, but you still must choose the correct one to use.

Choose the wrong one and your attack/release pots are essentially out of circuit which will probably cause it not to work as it should :wink:

BTW, I've added this to my 1176 FAQ (http://geocities.com/m_natsume/1176_FAQ.html).
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 21, 2006, 08:22:48 AM
Thanks for the suggestion, Mnats, but unfortunately its not that - I have that part right.  I'm also now certain I have R18 and R21 in the right way.

But something is not quite right, dammit! :grin:

I'm gonna have to shelve it for the rest of the week, so I can actually concentrate on work (or something else, at least) and come back to it with a fresh mind.

Thanks guys
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 21, 2006, 03:57:15 PM
I have exactly the same problem as You, sound but no compression. please let me know if You find out what´s wrong. hmmmm... I changed my mind Read my next one and You may realize that I have compression after all, not as much as I would like, but compression it is.
Title: What to expect from 1176?
Post by: stefan on August 21, 2006, 06:12:00 PM
Since I´ve never used an original 1176 I´m kind of wondering what to expect, should it have massive pumping almost distortion type of compression in the 20 setting? I have one up running now and the sound is fine, no hum after cutting two traces, all the controls seem to work properly, and I will certanly solder my other one together cause I realize that it will be higly useful in the studio, but still I´m kind of surprized by the humble action of the unit when everything´s is turned full CW. Should this not result in an almost useless mess? What I´m really wondering is if my unit is working properly or if the Bias (or something else) is wrong. I don´t have a meter in the unit yet so I really don´t know what the meterreadings look like, I just adjusted the Bias with an external meter. One question ´bout the adjustment, and this is a stupid one but I ask it anyway: where is the Biaspot supposed to be when I check for +1dB out of the unit?
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on August 22, 2006, 09:40:47 PM
I'm wiring the primaries on my toroid in parallel, but I don't know whether to connect the "start" of each winding to live or neutral.   I would assume live, but I'm confused by the two graphs below.  If I follow Avel Lindberg's site, it seems to show the blue/violet (start of the winding) would be connected to 0 (neutral, I assume) on the IEC connector.  Mark Burnley's graph shows the these two primaries being connected to Live.  

So which is it?  

(http://i8.tinypic.com/25akhzm.jpg)

(http://i8.tinypic.com/25akim0.gif)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 23, 2006, 04:14:10 AM
Quote
whether to connect the "start" of each winding to live or neutral


..Shouldn't matter..
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 24, 2006, 08:40:14 AM
The one advantage to living a 45 minute train ride from work is that I have lots of time to read the entirety of this post, and anything else I can find on this project  :grin: I'm sure my fellow travellers look at me strange when I unfold my A3 sized copy of the schematic, though!

I'm now pretty confident I know what my problem is - BF245A.  One of my problems was a lack of compression (my audio signal is fine, but no limiting occurs at any setting and the attack and release pots have no effect), and if I have it right, if Q1 has died then there's no chance of that.  I just tested the audio path using a signal detector (mark Burnley's wonderful little creation) and I have audio up to pin D on Q1, but not pins G or S.  I take it pin S goes to ground, so I don't expect audio there, but pin G heads to the attack and release pots (via R7 and point 7), so I assume that without anything passing that way, there ain't gonna be no compression.

Along the way my zero adjustment trimmer stopped having any effect (in GR mode, the needle just slams to the right and won't move, but when I first fired up I could adjust it with the zero trimmer) and my needle stopped responding at all to anything.  That's gotta be Q10, methinks.

Can anyone fault me on my logic?  Of course, there may be other problems lurking in the background once I replace Q1 and Q10 (note to other newbie's - when buying parts for this project, buys lots of BF245A, so you have spares when your first lot die on you, and so you can match them as has been explained elsewhere in this thread), but do I sound like my error-sourcing is on the right track?

Chris

PS My Vu meter definitely works - I connected it in series with a 3k6 resistor to my best piece of test gear - a 15 year old Sony Walkman  :thumb: All good!
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 25, 2006, 12:28:55 AM
Well, I've ordered a bunch of BF245A's which will hopefully arrive early next week.  I've also ordered a couple of 2x6 lorlin switches, as someone else in this thread described a similar problem to me and found it was a faulty switch.  If I'm wrong, then the spare switch goes into the 2nd channel or the GSSL that I intend to build  :cool:

I'll report back next week when the parts come in - hopefully with a grin on my face!
Title: All things G1176 - the new "repost" thread.
Post by: mnats on August 25, 2006, 08:38:36 AM
Quote
3. I haven't calibrated the unit yet. Do I need an oscilloscope to do this, or is there a workaround that will get me there?

You can do the "Q" Bias Adjustment and Gain Reduction Meter Tracking using your built-in VU meter. But because the G1176 rotary switch does not allow you to both observe the output or gain reduction on the VU meter and allow you to switch off the gain reduction, you will need a workaround.

Every time the calibration section of the 1176 manual says "Attack = full CCW (switched to OFF position), simply short pad 22 on the main board to ground (use a link with alligator clips or similar). This has the same effect as switching off the gain reduction using the Attack pot on the original unit. Every time it says to turn the Attack ON, just remove the link.

But you need a properly working unit before moving on to calibration, of course.

Quote
4. I when I put a signal through, and put the meter in Vu mode, the meter generally follows the strength of the signal, but never gets very "high" (i.e close to 0Vu)

What are you using as a test signal? The 1176 has loads of gain and even with a -20dB input you should be able to easily peg the VU meter.

Quote
I have audio up to pin D on Q1, but not pins G or S.

I wouldn't expect (much) audio on the gate of Q1, since it is fed DC from the Gain Reduction Control Amp (see CR3 and CR4). But with Gain Reduction ON, you should have plenty of audio at, say, the emitter of Q15 just before rectification. If not, something is wrong upstream.

Quote
That's gotta be Q10, methinks.

Seems very unlikely that both your FETs are faulty. More likely that the common circuit controlling them is where the fault lies.

Try removing Q1 and seeing what that does to your output strength. This will allow you to test the Signal Preamp and Line Amp without any sidechain circuit interaction. Once you're sure this is working properly, move on to the Gain Reduction Control Amp circuit.
Title: no gainreduction on meter
Post by: stefan on August 25, 2006, 12:43:29 PM
My first 1176 is up and running and everything seems to be working OK soundwise. The only problem is that when I set the switch in "GR" position the needle goes down to -20 and stays there regardless of how I adjust the trimmers. The meter(Sifam AL19) is working just fine in VU mode (as far as I can tell) but in GR nothing happens. where should I start?
Title: All things G1176 - the new "repost" thread.
Post by: mnats on August 25, 2006, 05:29:47 PM
Quote
where should I start?

Here. (http://www.groupdiy.com/index.php?topic=175488&#175488) Start in the lower left hand corner of the schematic or around IC1 (TL071) on the PCB.
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 25, 2006, 06:47:25 PM
Quote from: mnats

Quote
What are you using as a test signal? The 1176 has loads of gain and even with a -20dB input you should be able to easily peg the VU meter.
...
Try removing Q1 and seeing what that does to your output strength.


Using a 1KHz signal, at approx 0dB (measuring AC at my input read 0.777 VAC), which was loud enough to send my mixer skyrocketing  :cool:  I never got the meter moving much/at all.

With Q1 in, I adjusted the output so the meter on my mixer is reading 0dB.  I then pulled Q1, and got the exact same level on the mixer.  I changed between modes (i.e bypass, GR and VU) and ratios, and the output strength never changed :?

I get the impression my compression sidechain just isn't getting activated at all.

Quote
But with Gain Reduction ON, you should have plenty of audio at, say, the emitter of Q15 just before rectification. If not, something is wrong upstream.


No audio there, unfortunately.  I re-checked my power supply voltages (all good), and the voltages at Q12-15, and still all good.

Quote
Seems very unlikely that both your FETs are faulty. More likely that the common circuit controlling them is where the fault lies.


Could it be a faulty Q-Bias trimmer?  I am looking in the right area for the common circuit?

I'll keep hunting! Unfortunately I only ever seem to get about 10-15 mins at a time with it :sad:

Thanks for the help, Mako
Title: All things G1176 - the new "repost" thread.
Post by: mnats on August 25, 2006, 08:46:13 PM
Quote
Using a 1KHz signal, at approx 0dB (measuring AC at my input read 0.777 VAC), which was loud enough to send my mixer skyrocketing   I never got the meter moving much/at all.

I'm not quite understanding your signal chain. You are feeding your 1kHz, 0dB test signal into your 1176 and the output of the 1176 to your mixer? If you are saying that the mixer at the end of the chain was skyrocketing and the meter in your clone was not registering much when the rotary switch was set to VU, there is something wrong with either the VU meter (which you said you had tested earlier) or the connections feeding it. In other words, if your actual audio output meets or exceeds 0dB you should at least be able to see it on the meter since it is tied directly to the output when switched to the VU setting.

Get the VU meter working properly and ditch the mixer for now.
Quote
No audio there, unfortunately. I re-checked my power supply voltages (all good), and the voltages at Q12-15, and still all good.

The circuit that controls both FETs is the Gain Reduction Control Amp in the bottom middle of the schematic. You have no audio from the last stage of that amp when the clone is not in bypass. So start from pad 15 on the main board and trace the signal to pad 4 on the ratio board out to pad 22 back on the main board (which is the input of the control amp), then through the GR control amp circuit until you find out where the signal stops. Then apply Jakob's rule (http://www.groupdiy.com/index.php?topic=175488&#175488).
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 26, 2006, 04:15:20 AM
something is strange, I don´t have the -10V, I´ve soldered out C24,C26,R45,R82,R57,R56,R52,Q10 and pulled the TL071 out of it´s socket and changed the zener and still I have only around -4.5V! if I remove the zener and measure before it I have around -12V, am I measuring wrong or what is it? I thought that the unit was working soundwise and that the meter was the only problem but I´m not so sure anymore...
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 27, 2006, 08:26:19 AM
Stefan

What voltage do you get at R85?
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 27, 2006, 09:16:30 AM
...and it's "working" - not perfectly, but man, it's great to hear it compress something :green:  :green: .

My problem was, of course, a failure to properly apply Jakob's rule  :grin:  :shock:  :grin: Some free time, a strong light and hey presto - all the poor soldering job's on my board started leaping out at me.

Though I cleaned up some others, it looks like my problem was a poor solder joint on one leg of my tracking trimpot...now she goes!!!

A couple of questions about its operation, though:

1) It is meant to compress in Bypass mode, or does bypass just turn off the meter?  At  moment, in bypass there's no compressing going on, and the ouput level is significantly higher than when in Gr or Vu mode, which would make sense if bypass mode bypass the whole sidechain and not just the meter

2) In Vu mode, the meter still barely moves no matter strength signal I put through it.  This can't be right?

I might try a new u meter at some stage (I blew up the light in this one  :oops: ) to see if the meter isn't doing its job properly, but it seems to work ok in GR mode

Thanks Mnats for all the help - you're a legend!!!

 :green:  :green:  :green:
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 27, 2006, 03:31:57 PM
Quote from: "astrovic"
Stefan

What voltage do you get at R85?
If I unsolder The first 1K resistor (R86 I think) in the PSU and measure right after the 1N4003s I get only around -12V measured to ground is this right? I do not understand why I don´t have -30 or so, but I might be missing something obvious??
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on August 27, 2006, 10:11:30 PM
I take it you meant -10, not -30?

I checked for -10 after R85 rather than checking after the 1N4003's. This is the spot to check - see here (http://www.geocities.com/m_natsume/1176-wiring.html).  I'd work through the first part of this dealing with getting the PSU section right to see if it throws any light on your situation.
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 28, 2006, 02:17:17 AM
Quote from: "astrovic"
I take it you meant -10, not -30?

I checked for -10 after R85 rather than checking after the 1N4003's. This is the spot to check - see here (http://www.geocities.com/m_natsume/1176-wiring.html).  I'd work through the first part of this dealing with getting the PSU section right to see if it throws any light on your situation.
If I measure after R85 I would surely want -10, but if I measure right after the diodes, with nothing but the diodes and transformer in the circut, I don´t understand why I shouldn´t have -30?, well I have another board and another transformer so I´ll just build the PSU up on that one and see what I get. Thanks for the link, very informative. :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 28, 2006, 09:01:26 AM
I changed the 1N4003s cleaned up the soldering and replaced the TL072 that I had installed in the 071 socket :oops: unit is working!!!! I had a feeling that something wasn´t quite right with it soundwise but now it´s behaving much more like I expected it to.
Title: All things G1176 - the new "repost" thread.
Post by: rotation on August 29, 2006, 11:39:43 AM
Hi!
I hope you guys don't mind answering this question one more time.
After good success and little problems with mass around in/out circuitry on Gyraf's GSSL i'm buying pcb for 1176. I would like to know if all problems with Gyraf's boards for 1176 are now solved.
Thanks in advance!
Miha
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 29, 2006, 12:53:28 PM
The only possible problem is the pcb copper trace you need to cut in order not to risk running into noise-trouble. But that's well-documented.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: rotation on August 29, 2006, 01:03:13 PM
Aha, thanks for the reply.
Miha
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on August 29, 2006, 05:53:31 PM
Mnats specifies a 2.2M carbon resistor for R7 and R9, while Jacob's and Greg's parts lists don't specify metal or carbon.  Is there any reason or benefit in using a carbon resistor here?
Title: All things G1176 - the new "repost" thread.
Post by: sintech on August 29, 2006, 06:46:22 PM
MattiasC,

Any 2m2 resistor will do fine.  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on August 29, 2006, 06:48:34 PM
hi MattiasC,
just use whatever you have.  generally metal film are used because they have lower tolerances (usually 1%) and are less noisey than carbon film, but it really shouldn't matter in just R7 and R9.  Just use which ever is more available to you.  
regards,
grant
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on August 29, 2006, 06:49:26 PM
:thumb:
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 30, 2006, 04:13:27 PM
is there any danger in having the heatsink of the 7825 touching the top plate of the box? I´m building in 1U case and things are getting tight.
Title: All things G1176 - the new "repost" thread.
Post by: sintech on August 30, 2006, 06:06:24 PM
I'd make sure your 7825 is isolated from the heatsink with a mica washer or similar. Otherwise the centre pin will be shorting to ground.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 31, 2006, 01:39:48 AM
7824, not 7825..
Title: All things G1176 - the new "repost" thread.
Post by: stefan on August 31, 2006, 02:27:40 AM
Quote from: "gyraf"
7824, not 7825..
of course it is, my mistake
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on August 31, 2006, 06:03:11 PM
I wound up with 10uf/50v caps for the balanced input section rather than the specified 10uf/35v.  Will this cause me any grief?
Title: All things G1176 - the new "repost" thread.
Post by: sintech on August 31, 2006, 06:06:09 PM
MattiasC,

10uf/50v will work fine. :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on September 02, 2006, 09:41:02 PM
Thanks again, Sintech.  I'm a noob, so forgive me if these questions seem redundant.  

The potentiometers have a metal tab which I assume is there to attach to the faceplate.  Is the only way to attach it to drill a hole?  I don't want to risk cutting through the front of the faceplate.  What are my options here?  I'm about 5 seconds from cutting that sucker off.

(http://img82.imageshack.us/img82/1020/mail1uj5.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 02, 2006, 09:56:29 PM
Quote from: "MattiasC"
Thanks again, Sintech.  I'm a noob, so forgive me if these questions seem redundant.  

The potentiometers have a metal tab which I assume is there to attach to the faceplate.  Is the only way to attach it to drill a hole?  I don't want to risk cutting through the front of the faceplate.  What are my options here?  I'm about 5 seconds from cutting that sucker off.

(http://img82.imageshack.us/img82/1020/mail1uj5.jpg)


I cut them off 99% of the time... go for it. Won't hurt a thing. Just tighten the nut as firm as you can so the pot doesn't spin :wink:

Kevin
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on September 02, 2006, 09:58:51 PM
Thank you!
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on September 09, 2006, 07:51:39 PM
Well, I had mine up and working for a short time.  Thanks for all the help here.  It definitely added some cool character.  Unfortunately, I fried R89 while trying to measure the VU meter voltage.  I don't know if the 7824 is cooked as well, but hopefully not.  Any advice at this stage?
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on September 10, 2006, 08:11:59 PM
Changed the 7824 and r89 and everything is back to normal.  Thanks to Sintech, Mnats, Bill Putnam, and especially Jakob for putting it all together.
Title: All things G1176 - the new "repost" thread.
Post by: byoung on September 18, 2006, 02:09:28 AM
I've spent the day stuffing my Mnats board and have a couple questions before I can continue.  

1) where is R50?  on Mnats BOM it says it is not used on the gyraf version and I can see it on any of the boards? It's an 8.2K

2) on Mnats BOM he lists 2 220pF ceramic caps at locations C3, C4(where the schematic say 200p)also a few parts down on his BOM he lists 1 220pF ceramic cap at location C32.  So should I use the same 220p caps for all three locations?

3) I used Gregs BOM to actually order from, and there are 220p 5mm 50v poly caps, and 220p 100v ceramic caps, So this is in reference to question #2, where do these different caps go?  I've tried looking at the schematic to figure this out but am still a little confused.

4) Also on Mnats BOM there are 47uF electrolytic caps at locations C9, C11, C34,  and then there is a listing for a 47uF/35V electrolytic at C18.  I'm assuming I can use 47uF/35V at all these locations?

Thanks
Brian
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on September 19, 2006, 10:20:12 PM
G'day Brian

As best as I can:

1) R50 doesn't go anywhere, in either the Gyraf or the Mnats boards. I think previous posts have explained the history of R50.

2 & 3) C3, C4 and C32 all can use the same ceramic capacitor - the 50v should be fine.  I used them for C3 and C4 (I haven't installed C32 as I used the transformer input approach, but the same cap should work)

4) 47uF/35v works at all locations - that's what I did

Hope this helps!
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 20, 2006, 04:11:58 AM
I looked for these answers but couldn't find what I wanted...

(I'm using the MNATS New version board)
I know SOME of the (*) components are needed when using the input tranny but there are others in the Gyraf version. Mnats says he doesn't install them but I've seen others, like Greg for instance, installing them even without an input tranny... WHY?

Could some one explane what they're there for?

For instance, the 1000uf/35v next to the 2.2k trimmer... for one thing, a 1000uf/35v cap doesn't even fit in this spot, especially on my Mnats board :?

Could someone shed some light on this?

Why are they optional & what do they do... in or out of the circuit?
I'm using the BD135/136 output trasistors if that makes any difference.

Thanks,
Kevin
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 20, 2006, 04:39:55 AM
Hi Kevin,

If you compare the schematic and the layout, everything should be clear. Nothing wrong in mounting all parts, just some may not really be needed.

Jakob E.
Title: .
Post by: glide 1 on September 20, 2006, 10:58:37 AM
Hi All,

I'm new to the boards aswell as DIY. I've recently purchased Mnats's boards and decided that the 1176 project would be my first attempt at DIY. I will be using a trnsformerless input and the OEP output trafo

I spent hours and hours the past few days reading every bit of info there is on the 1176, seems like the more i read though, the more i believe i can tackle this project......Crossing fingers AND toes!!!

I have a question. On Mnats' BOM, which Caps in particular would you recommend me spending money on? the prices range from a few cent to $5, and some even more. Is there actually an audible difference using expensive caps or is it more for reliability and better tolerances of the components in general. If someone could list these caps mentioned above , i would appreciate it a lot thanks.

There will be more questions later i'm sure, just thanking everyone in advance for all the knowledge you so readily give to us newbies....Mabuhay Prodigy!!!

glide 1
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on September 20, 2006, 08:13:27 PM
G'day Glide - welcome aboard

The 1176 was my first major project, and it rocks (can I show it off? (http://www.groupdiy.com/index.php?topic=18037)).  Prior to starting I read a lot of threads discussing other people's completed builds, and decided to settle on Nichicon PW electrolytics and Panasonic ECG for most of the others.  WIMA is a popular brand as well around these parts.

I don't think you need to go as high as $5 to get decent quality caps, though.

Try doing some searches on "WIMA" and "Nichicon" and browse some of the posts, as these searches will throw up a lot of results where the qualities of various caps are discussed, by people far more qualified to do so than me.

If you haven't seen it yet, have a look at Greg's BOM's (http://www.groupdiy.com/index.php?topic=14059&highlight=bom) as they are just brilliant.  Just looking at his BOM for the 1176, I see I used the caps listed there, and I don't think that was an accident  :grin: My unit rocks, so those caps must be good  :thumb:

Finally, is this your first ever project?  If so, you might want to have a crack at something a little simpler first to "get your eye in".  My first build was a DI box using a JLM di kit (as per Kev's JLM Simple DI page (http://www.diyfactory.com/projects/jlmsimpledi/jlmsimpledi.htm)), then a PAIA tube mic pre kit (http://www.paia.com/tubestuf.htm), before trying the G1176.  I'm very glad I started with the simple stuff first!

Welcome to DIY!

Chris

PS Yes, I am enjoying do the think with the links to other pages by clicking on the text.  Just figured how to do it!
Title: All things G1176 - the new "repost" thread.
Post by: MattiasC on September 21, 2006, 01:06:31 AM
I'd like to chime in here since I just finished my first G1176 (which I'm loving).  

Before this project I'd only done small DIY projects, all of which allowed me to get away WITHOUT reading the schematic.  Not so with the G1176.  With this one I was FORCED AGAINST MY WILL to learn how to read it.  

If you haven't sat down with the schematic to learn what's going on, you really owe it to yourself to get this out of the way before you continue.  I promise you will be happier you did, and you will spend much, much less time searching the forums.

Good luck!
Title: astrovic, MattiasC
Post by: glide 1 on September 21, 2006, 09:57:03 AM
Quote

The 1176 was my first major project, and it rocks (can I show it off?). Prior to starting I read a lot of threads discussing other people's completed builds, and decided to settle on Nichicon PW electrolytics and Panasonic ECG for most of the others. WIMA is a popular brand as well around these parts.


astrovic, MattiasC,


Yes the ECG's, Nichicons and Wima's i've seen being mentioned here a lot, will look into that. The "Bemble 1176" i did see too....looks very nice. i might opt for the OEP input aswell later on. I have Greg's and Mnats' BOMs printed out, so will be basing my parts purchase on these.


Before this project I'd only done small DIY projects, all of which allowed me to get away WITHOUT reading the schematic. Not so with the G1176. With this one I was FORCED AGAINST MY WILL to learn how to read it.


I'm in the same situation as you, very minor repairs on gtr amps, efx pedals etc. - no real DIY projects under my belt as such - yet. With this 1 however, i've talked to a friend already about helping me build. So much to learn and i'm very exited!!


Thanks for the welcome and advice guys...much appreciated

glide 1
Title: All things G1176 - the new "repost" thread.
Post by: on September 21, 2006, 10:18:51 AM
Hi guys and gal's!

This will be my first post here (but certanly not the last), and i must say it feels good!  :cool:

I finished my 1176LN clone this weekend.
I fierd it up (holding my breath anticipating things to start smoking).
Belive it or not, IT WORKED!!!!!  :grin:
No, hum, noise and other bad things.
This is my first project that has been without ANY bugs.

BIG thanx to Mr Gyraf and Mr MNats for a great design!!!    :guinness:  :guinness:  :guinness:  :guinness:

I have some questions though:

What is the purpose of having lowleakage diodes (FDH333)?
Some capacitors on MNats board are marked with asterisk, why?
I could not find any ifno on them.
Maybe i should look harder.

I will probably post a thread when i get the panel done.

Thanx 1k times again!


/Hampus
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 21, 2006, 12:37:05 PM
Low leakage diodes are needed, because we want to keep the "floating" DC offset after the diodes undisturbed. This DC-potential is very High-Z. All leakage would draw the whole circut in the wrong direction.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 21, 2006, 09:57:27 PM
Quote from: "gyraf"
Hi Kevin,

If you compare the schematic and the layout, everything should be clear. Nothing wrong in mounting all parts, just some may not really be needed.

Jakob E.


I realize that the extra parts are not needed I just wanted to know WHY they were added in the first place... what do they do? Like the 1000uf/35v  electro that I couldn't fit on my board if I wanted to :mad:

I just want to learn, that's all.

& since you designed it I was hoping you could be more specific :green:
I can't be the only one who would like to know... am I :?

Kevin
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on September 21, 2006, 11:14:51 PM
Quote from: "cosmox"

Some capacitors on MNats board are marked with asterisk, why?
I could not find any ifno on them.
Maybe i should look harder.


http://www.geocities.com/m_natsume/1176_FAQ.html - see the answer to the first question...

Otherwise - congrats!  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 22, 2006, 03:29:01 AM
Quote from: "astrovic"
Quote from: "cosmox"

Some capacitors on MNats board are marked with asterisk, why?
I could not find any ifno on them.
Maybe i should look harder.


http://www.geocities.com/m_natsume/1176_FAQ.html - see the answer to the first question...

Otherwise - congrats!  :thumb:


My point exactly... Mnats basically says they're not needed for a working clone.

I got that part :wink:

But there has to be a reason Gyraf put them there... that's what I would like to know. It's like - I can't make a decision about an optional component when I don't know what it does in the first place.

Just saying, go ahead and put them in (or not) doesn't make sense.

Kevin
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 22, 2006, 03:32:51 AM
Quote from: "gyraf"
Hi Kevin,

Nothing wrong in mounting all parts, just some may not really be needed.

Jakob E.


Could you be more specific.
I really don't mean to be a pain in the ass, I'm just curious :green:

Kevin
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 22, 2006, 05:12:42 AM
I don't really know the MNATS version in detail, but it looks like e.g. C*1 is additional psu stabilisation. And that is always a good thing.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: on September 22, 2006, 11:56:27 AM
Thanx for the earlier replys.

Now I have some questions about the VU meter.
Since i have a hard time getting hold of nice looking VU meters I'm thinking of using an A-meter (mA).

What is the prefered internal resistanse for a A-meter?
How does the rectification work, how is it hooked up?
What is the inpact of rectification resistance?

Regards/

Hampus
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on September 23, 2006, 06:14:47 AM
Excuse me if I missed :oops:
Phase on output transformer (Lundahl) of Mnats and Jacobs project are diferent.
Title: All things G1176 - the new "repost" thread.
Post by: W DeMarco on September 23, 2006, 05:54:28 PM
Hey folks

Im real excited to see that the voltages on the regulator are all clean and Im passin audio through my new 1176.  I noticed on the oscope a strange waveform on VU mode.  Excuse the error in the pic as I mixed up bypass and vu mode.  This appears when set to vu mode.  Wondering if anyone can shed some light on this.  Pics at http://www.vuturevisions.com/g1176/1176prob.html

Thanks

Will
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 25, 2006, 02:09:41 PM
Quote from: "dukasound"
Excuse me if I missed :oops:
Phase on output transformer (Lundahl) of Mnats and Jacobs project are diferent.


I THINK Mnats just flipped the PAD's & not the Phase but I'm not sure :?:

I would like to know this as well.

Kevin
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 25, 2006, 05:42:15 PM
The Mnats board has the option for 1:1 or 2:1 for the Lundhal...

Which is the setup most of you are going with & why?
It says 1:1 is normal but I think the original is 2:1, no? :?

Also, any difference between using the 10k or 12k for the secondary loading :?:

Thanks,
Kevin
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on September 26, 2006, 01:28:20 AM
Quote from: "khstudio"
Quote from: "dukasound"
Excuse me if I missed :oops:
Phase on output transformer (Lundahl) of Mnats and Jacobs project are diferent.

I THINK Mnats just flipped the PAD's & not the Phase but I'm not sure :?:
Kevin

Please compare Lundahl polarity with + and - signs on pcb.
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 26, 2006, 03:22:19 AM
original is 1:3.5

10db of transformer gain

mnats has 1:2, 6db of o/p tx gain.

gustavs board is 1:1, 0 o/p tx gain, ignoring losses on all those numbers


currently i have stancor wf30 1:1 on the input, and oep on the output at 1:2, mnats board.

i have way more gain than i could hope to use.

in fact, this thing is cool for dynamics.  and i went to a buddy's and tracked some p-bass direct in, no di, and for one song it sounded awesome.  on another it was good, but not what the song called for.

regardless, theres tons and tons of gain.

i'm actually thinking about building the electronically balanced version, just because its 'normal' and is according to the rev F schematic, and then pulling the oep and putting on a hand wound clone of the old one.

i'll report back when i get a chance to do this....
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 26, 2006, 01:08:22 PM
Great info :thumb:

BUT... I was reffering to the Input Tranny :green: My fault.

Quote
The Mnats board has the option for 1:1 or 2:1 for the Lundhal...

Which is the setup most of you are going with & why?
It says 1:1 is normal but I think the original is 2:1, no? Confused

Also, any difference between using the 10k or 12k for the secondary loading Question

Thanks,
Kevin
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 26, 2006, 03:27:18 PM
got you ;]

sorry....  it seemed duka was mentioning the o/p, so i thought it was continuing...

anyway, g1176 is like a rev F with a rev G (5532) frontend.

the rev F has an O-12 with 500:200 (1.58:1) ratio.....  witha  constant impedance presented to the input transformer.  

g1176 with an i/p transformer is on the pcb as 1:1, but in my very humblest opinion, i would go for 2:1 stepdown....  its a matter of 2 solder connections, so try it and see what you think of each.....  see how much headroom you get on the input knob, and where your compression is kicking in (threshold) when you set up the box.

its really something that should be done with 'feel'

having tried a stancor wf30 onmy input as both 1:1 and 2:1, i'm honestly not a huge fan of either....  personal opinion, and an opinion that has no experience with a real 1176.   just not working the way i want it to.

thats why i'm going to build the 5532 section, and test out this o/p tx clone....  hopefully my hand-wind will work out ok, and hopefully i can try it side by side later tonight and report back.

have to go to mcmaster for a 24mm step drill and some garolite ;]

but honestly it comes down to seeing what you like... its kinda personal.  theres no right way in this situation, because the g1176 with i/p tx isn't like any of the orig. 1176ln's, so 'right way' is moot.  go for what sounds good and works well for you.

if you're after 'original,' and its important that its like a 'real' one, go elec. balanced, or find yerself a t-attenuator and a utc O-12, or even an a-20 would work out... the stancor wf-30 i have is a clone of an a-20, same specs... and the O-12 in the original is just the mini/ouncer version of the a-20 (essentially).....

there are some other threads around (cant remember which) that also have some opinions, thoughts, and facts regarding the input transformer and the g1176 (and 1176ln)
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 26, 2006, 06:44:58 PM
Thanks for your advise & input :thumb:

I'm finishing up 2 units TONITE :green:  & NEED some last minut advise:

The pins that connect the main board to the Ratio switch board -
Do any of them NEED to be shielded :?:

pins ( 22  21  19  7  20   18 )


Is it OK to use SOLID CORE wire for those  :?:
 - I know it can break easier but are there any SONIC benifits to either  :?:

Thanks,
kevin
Title: All things G1176 - the new "repost" thread.
Post by: Greg on September 26, 2006, 08:00:48 PM
I ONLY shielded I/O wires, NOT the wires to the RATIO switch.

Don't expect any SONIC difference between stranded or solid.
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on September 26, 2006, 08:25:12 PM
Quote from: "Greg"
I ONLY shielded I/O wires, NOT the wires to the RATIO switch.

Don't expect any SONIC difference between stranded or solid.


Cool :thumb:

I assume your unit is working fine (Quiet) or you'd have said something by now.

Thanks man,
Kevin
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 26, 2006, 08:28:31 PM
also, the schematic shows what was shielded on the urei's

theres an "imaginary" sleeve indicating shield.

some of the frontpanel wiring was shielded, some was not, although most likely none of it is super critical.

your choice....   BUT check out mnats page for his wiring instructions....  really really helpful.....
Title: All things G1176 - the new "repost" thread.
Post by: Greg on September 26, 2006, 11:17:58 PM
I used the original Gyraf board, so I had to cut a trace or two and beef up the ground plane to get it quiet (and it's very quiet). But no worries on the mnats version. Only other thing I did was used shielded cables on the I/O.
Title: All things G1176 - the new "repost" thread.
Post by: imo on September 27, 2006, 12:01:33 AM
I hope everyone is well, recording, building, etc.
I just got back from another short tour and had a couple of continued questions/ queries about the 1176 threshold. Brad, apologies in advance, but it seems that i still haven't solved my threshold issues.
Jakob had suggested a mod putting a 100k trimpot in series with the sidechain input: one side to the top leg of the output pot, the wiper to the 56k(r26) at input and the other side of the trimpot to ground. When i originally connected the trimpot i accidentally connected the wiper to the other side of R26( between it and the 68k(R25)). When i connected it to the correct side and put the unit on a scope i wasn't able to see any alteration of threshold at all through the whole run of the trimpot. Ironically connecting the wiper between R26 and R25 gave me exactly what i was looking for(being able to take the threshold to a more usable level). This has left me a bit baffled as to what is going on. Am i missing something here??
I have also read a bit about some of the 1176 variations using a 2:1 stepdown transformer, which would seem to offer a more usable threshold.
Using the trimpot the way i am, the ratios seem pretty close, the only problem being the 4:1 is closer to 5:1. The other ratios are almost spot on..
Brad, did you ever put the unit on the scope while turning the trimpot? I am wondering if you possibly hooked it up the same way i did by accident, or if i am simply completely turned around.
Ian
Title: All things G1176 - the new "repost" thread.
Post by: mnats on September 27, 2006, 08:18:46 AM
Quote from: "dukasound"
Excuse me if I missed :oops:
Phase on output transformer (Lundahl) of Mnats and Jacobs project are diferent.

I'm not sure if I understand correctly, but then I don't have Jakob's board in front of me either. But what I do have are my own boards and the Lundahl and OEP output transformers that fit in them.

Here are two images of a 1kHz sine wave at the input and output of a working 1176 using my boards. First with the OEP:
(http://www.geocities.com/m_natsume/images/1176_io_oep.jpg)
The smaller trace is the input and the larger is the output of the OEP with the probes on the + side.

Next the Lundahl:
(http://www.geocities.com/m_natsume/images/1176_io_lundahl.jpg)
It looks correct to me and seems to agree with the designations on my boards. Are you saying that Jakob's boards work differently? Can you show us?
Title: All things G1176 - the new "repost" thread.
Post by: Greg on September 27, 2006, 09:25:47 AM
Those look in phase to me  :thumb:

Except one of those sine waves in the second shot seems to be "bulging" a little.
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on September 27, 2006, 02:17:27 PM
OK
Bad english :sad:
I ask this:
If we used Lundahl on out and wired 1:2 or 2:1. Both primary and secondary are wired in series.
On both Jakobs and Mnats boards C15 ? 470uF is connected to minus of Lundahl transformer (pin 1 for 2:1 and pin 10 for 1:2) and plus of windings (pin 4 and can 3 for 2:1 and pin 7 for 1:2) goes to ground.
On Jakobs pcb Bal. Out plus goes to pin 9 who is positive.
On Mnats board (1:2 ratio) Bal out plus goes to pin 5 who is negative.
It is it.
Title: All things G1176 - the new "repost" thread.
Post by: mnats on September 28, 2006, 06:35:08 AM
I get it now - you're saying the polarity of the output is reversed on Jakob's layout. Can anyone who has built one confirm with a simple test?

Anyway, it's an easy fix - just switch the wires.
Title: All things G1176 - the new "repost" thread.
Post by: Greg on September 28, 2006, 07:55:17 AM
I'll grab my G1176 in the coming days and see if the polarity is being inverted.
Title: All things G1176 - the new "repost" thread.
Post by: dukasound on September 28, 2006, 12:57:45 PM
Quote from: "mnats"
I get it now - you're saying the polarity of the output is reversed on Jakob's layout. Can anyone who has built one confirm with a simple test?

Anyway, it's an easy fix - just switch the wires.

OK.
We discuss here to learn anything :grin:
Title: 1176 stuck in the canal:
Post by: W DeMarco on September 28, 2006, 10:26:13 PM
Hiya folks,

Lookin forward to gettin my G fired upp but I am experienceing a couple of problems.  First thing is that my VU is pegged full right in GR.  Its a sifam 29, brand new, with the 24 volt light box!!.  It seems to fuction well in VU mode and really extra well in Bypass.  Here are a couple of things i've attempted that are suggested in the forum.  

replaced VU fet.  
pulled a bunch of resistors and replaced.  
replaced tl071

I know the trim is working cause if I put enough input it compresses enough to where I can trim it up and down.  although the trim doesnt affect the VU when no compression is happening.  Im not sure I need a resistor attached to the VU.  I have a 3k6 on that bastard right now but noticed that the 1k test tone on my small 2 channel shure field mixer is about -3 db with the resistor attached. Without it its measuring a hair above zero.  Im geussing for +4 db I wont need it.


2nd problem is that I can't seem to get the Q bias to do a darned thing.  Im setting it up like I have seen mentioned on Gyrafs site and in the 1176 manual.  I saw someone talk about attaching DMM to the output pot but Im a bit confused about this one.

When a resitor take forever to creep up to almost spec on my DMM should I replace. A few of them are real slow others show their value immeadiatley.  

If someone could enlighten me or direct me to a good post on the technique!  It seems to pass audio well no problems yet although all its heard is a sine wave yet :green:

Thanks

William
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 28, 2006, 11:08:44 PM
hey william...   do you have a 3k6 resistor directly on the VU meter??

If so, and you are using jakob's or mnat's pcbs, it's unnecessary as there is a 3k6 mounted on the meter switch board for just the purpose.

Also, when you talk about measuring resistors, is it slow while measuring resistors on the board, or just on loose resistors?

You can, and often do, get different measurements when measuring resistors soldered on to the board.  If you're using the DMM to make sure the resistors are correct, a much better way is to print off a resistor color code chart and start checking against a print out of the pcb layout from the gyraf or mnats website.

Also, are your FETs socketed?  I've had problems using non-machined sockets for the FETs.  You may want to try wiggling the FET in place, and watch for correct meter movement....

but again, if you indeed have an extra 3k6 resistor in addition to the 3k6 that's on the meter switch pcb, that is most likely the problem.

Regarding the setup, I wouldn't even attempt it until the meter is behaving, but once you get the meter issue sorted out, the setup procedure should probably be done a few times....  honestly, once you've done it 7 or 8 times, you will have it down.

Also, 2 accurate AC millammeter or a dual trace scope is honestly the only good way i've found to set up the GR Tracking.

With a dual trace scope it becomes no problem...  with just a single DMM, you will want to slit your wrists.  At least I did anyway...  it's really a very hands on experience.

Billy

how bout that, it looks like you're about 5 miles north of my hometown ;]
Title: Reply to Billy
Post by: W DeMarco on September 28, 2006, 11:23:36 PM
Thanks Billy,

I do indeed have a resistor on the sifam but only put it there after I noticed the vu was pegged.  I was hoping it was the problem solver.  Guess not huh?  So Ill remove and try again.  I soldered the FET in directly.  So its not mechanical, unless i roached it. The slow dmm reaction was ocurring measuring on board resistors.  

Ill print a chart and go through them again.  

I do have a dmm and a dual trace but lets wait like you said on the Q bias!

Last time I was in Kent I stopped in at woodsies where they had two Spectra 610's ridin low in a rack on the floor.  We asked what they we're doin there and he said that they have been for sale on the floor for 10 years or something like that.  I quess they we're the final pieces left from the old studio there.  Get this he sold em both to me for 500 bucks!!

I love that town


William
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 28, 2006, 11:41:24 PM
man, i never saw those in there!  i wouldn't have bought them, but i'd be proud of finding them, and i'd have asked to plug em in ;]

i honestly wish i could remember why my vu's pegged on my units... it happened just as you have happening, but i dont remember what fixed it for me.

what i do remember doing, however, is going through and checking every single resisitor with the chart on two units.  and it solved something.....

and then i had the magic fet, that would begin to indicate GR on the meter when, and only when, a finger or metal probe was in close proximity to, but not touching, the fet....  it was some loose spot somewhere, no ground, something like that....  i think that may have been the socket i used....  i think i replaced the sockets and had much better luck.

if you dont decide to put some in, solder them high, so you can get in there and clip em quick n easy and replace.

I went through around 10 or 20 FET's, but i was attempted to stereo match...  which ended up not working as well as i hoped ;]

but alas, i have two great working units here.... now to try this alternate input tranny i wound, find out what its made of ;]

with the qbias, first get your signal, something steady and sinuous, in the neighborhood of 850mV rms (multimeter) or 1.2 Vpeak to peak on the oscope.  Approximately that ballpark.  Plug the output of the g1176 into a daw input and meter in PT or something that works for you....  adjusting input and ouput, and get it to +1db on the DAW meter.

then, go ahead and and turn the qbias all the way down, counter clockwise.  eventually, you'll get nothing.

then you can turn it up until you get 0db on the DAW meter.

Try and let the unit warm up for a good bit first, 30 mins at the least.
Title: All things G1176 - the new "repost" thread.
Post by: W DeMarco on September 28, 2006, 11:47:57 PM
Right on,

I'll go through the resistors again and report back the results..  Shouldnt be to tough.  I already checked all the interconnects as well.  So whats hot down in Kent these days.  Any good bands out there?>

Will
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 28, 2006, 11:51:36 PM
there's some cool stuff going on...  there always seems to be a secret coalition of amazing music going on beneath the small college town veneer.

beaten awake is doing real well for themselves, play a fine show if you get a chance to see it.

i saw you recorded finless brown, very cool...  used to play some shows with them before they moved....  i was in low in the sky and kind of honeypot and had played some shows with them.

to g1176 builders: sorry for getting Off Topic, espeically if this is the year 2010 and whoever's reading this is digging seriously deep down to find an answer....  sadly, I don't have it....
Title: Gettin there
Post by: W DeMarco on September 29, 2006, 01:09:19 PM
So I found a few problems that I had hoped would clear up my GR mode peg,  things like installing the ratio switch reversed,  a couple of lame solder points...  

The ratio switch probably solved my problem with the Q bias but it didnt help my gr mode vu problem.

Heres a big discrepancy I found between Gyrafs scheme and a bom I used.  For the tracking Gyraf calls for a 500 k trim.  In my bom I have a 100 k called for.  That sounds like a big difference to me.   At least if it was money it would be big diff!   Im gonna hit the surplus shop and pick up a 500 k if their cool enough to stock it.  

By the way I saw a killer weller solder station at hgr industrial surplus that the had listed for 90 bucks.  However everythings on sale.  I live about two miles away from the warehouse so if anyone ever finds something of use there I can check it out.

W
Title: Update
Post by: W DeMarco on September 29, 2006, 07:57:38 PM
I got a 500 k trim pot and installed which didnt help to much if at all.  Meter is still pegged.  This morning I did the resistor check which went, for the most part well.  I have a led spelunkers light that complicated the issue.  Playing tricks with my eyes.l;  BTW what type of light works best for id'ing resistors?


So I picked up a bunch of FET's at electronic surplus:  They are the 2n5457 type that Gyraf has listed for the substituted original.  Noob alert:  is it alright to use these?                    If it is and they are rare there are probably 100 more there!!

Anyone have a suggestion.  Im real excited to get this monster up just a couple of gremlins to go!!

W
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 29, 2006, 09:33:06 PM
i think i used the 100k, but i cant remember for sure....  the 500k will be just fine, may be a little less range for the 'sweet spot' but it covers 0-100k, plus and extra 400 more k!  will be fine.

for the meter, check the ratio board very carefully, and check the wiring to the ratio board......  the ratio board has quite a few things that affect the meter when set to GR mode.  if there's a short on the ratio board, there are quite a few places that would cause the meter to peg one direction or the other.  same goes of course for the meter switch, but since you started posting, i started remembering issues on my ratio board... i actually believe it turned out to be a little strand of wire wisping into another.  gotta watch those guys.  are you hard wired or using crimp pins to the frontpanel?
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on September 29, 2006, 09:38:35 PM
my folks are in town for the weekend, but i think i'll probably get a chance late tonight ( ;] ) to do a couple mods to one of my units for an A/B, which will require a recal

so that'll freshen me up, i can be a bit more helpful....
Title: No Luck yet,
Post by: W DeMarco on September 30, 2006, 01:44:48 PM
I've been checking rechecking swapping things out and I still have a pegged VU in GR mode.  I think its the only problem anymore.  

I went through both switch pc's continuity is in place.  Im gonna go through my pot connections again and see if that might be a factor.  

Any other suggestions.  

William
Title: All things G1176 - the new "repost" thread.
Post by: byoung on October 02, 2006, 02:57:20 AM
I have a question about using OEP's on Mnats board, the two R* and R*1  resistors are only changed from 10K to 12K if you use Lundahl wired 1:1, so for OEP's in either orientation I should use 10K, is this correct?

Also I'm curious, since this is my first project with transformers, what do I get from wiring them reverse, ie do I get more headroom, gain etc. on the input if wired 2:1 compared to 1:1 or how about on the output, less gain, more gain, less headroom?  I'm just curious how the wiring of the transformers affects the unit and sound.  If this has been talked about somewhere else can you point me too it?  I couldn't find it via the search engine.

Thanks
Brian
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on October 02, 2006, 04:53:33 AM
hey brian...  go for a 10k there.

the original revisions of the 1176 that the g1176 is based on had a 10db step up at the output, and this is why, on mnats board, the output transformer is wired 1:2, to get 6db extra gain to closer match the original.

to do that, on the output, just install the oep as it is on the board.  If I remember correctly, the input transformer is wired 1:1.  On the original, there was no input transformer.  On previous revisions that *did* have an input transformer, it was wired 500:200.  There are a lot of posts about all this, but basically, try it out as is....  see how you like it.  If you feel you need to hit the compressor a bit lighter, you can try wiring the oep off board with a stepdown.

If you want, you can also install a couple pins on to the board so that you can use alligator clips on an upside-down oep while you try different windings and experiment before commiting with the soldering-iron.

its a picky issue, and you have to decide what you like and how you prefer to use the tool.  if you haven't yet, print all the relevant material, like the schematic, the pcb layout from mnats site, and the oep datasheets from the oep site.  these are invaluable while you are working on it, especially if you experiment with windings amd ratios

billy
Title: All things G1176 - the new "repost" thread.
Post by: mnats on October 02, 2006, 05:05:18 PM
Quote from: "byoung"
so for OEP's in either orientation I should use 10K, is this correct?

Quote from: "enthalpystudios"
hey brian...  go for a 10k there.

You've tested this in both configurations?
Quote from: "enthalpystudios"
to do that, on the output, just install the oep as it is on the board.  If I remember correctly, the input transformer is wired 1:1.  

My last revision of my boards has options for different ratios on both the input and output transformer including 1:1 and 2:1 on the input; 2:1, 1:2 and 1:1 with the OEP on the output and the original 2:1 and modified 1:2 on the output. I did that to encourage experimentation, hoping that my fellow Lab Rats would try it out and post some results.
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on October 03, 2006, 12:38:27 AM
Quote from: "mnats"
My last revision of my boards has options for different ratios on both the input and output transformer including 1:1 and 2:1 on the input; 2:1, 1:2 and 1:1 with the OEP on the output and the original 2:1 and modified 1:2 on the output. I did that to encourage experimentation, hoping that my fellow Lab Rats would try it out and post some results.


sorry, didn't know that!  i seem to only be able to pc-mount an oep in one direction at both input and output on my board.

so, if the oep is installed any other way at the input, i'm out of my element  :oops:

sorry about that.....
Title: switches
Post by: glide 1 on October 06, 2006, 11:03:38 AM
Sorry if this has been asked before.. Would these switches from ITT Cannon work on the Mnats 1176?

farnell order code 1701605 and 1701629


Also, i'm also looking for alternative pots to the Alpha (Taiwan) type used on Greg's BOM. 5M, 25k, 100k, 10k all from the same range and brand, just wanting them to all have the same feel /tension when turned. Thanks
Title: switches
Post by: W DeMarco on October 06, 2006, 12:48:37 PM
Make sure that you read the tech sheets.  I noticed that the switches your asking about have solder lugs,  youll want pc mount for Gyraf or MNATS boards. Basically the z in the manufacturers product number should be a c. Also you'll need to be able to program the switch to different position amounts.  This is usually a small washer with a tab on it that you drop into the appropriate slot on the switch.  The ones on the BOM that your using should give you some insight to what the paticular needs are.
Title: All things G1176 - the new "repost" thread.
Post by: glide 1 on October 06, 2006, 01:25:54 PM
Thanks for pointing that out W DeMarco.

I see also that a 2pole 6pos switch is used on the 1176 but effectively only has 4 selectable ratios.... Is this what you mean by being "able to program the switch" so that only the 4 positions are used?
Title: VU Meter
Post by: glide 1 on October 06, 2006, 02:06:29 PM
I found a pair of VU Meters from an old Denon tape deck, it has 4 terminals; 2 for the meter (i believe, - have'nt tested), and 2 for the light (i know because i checked if the bulbs work with a 9V battery).

My question is, What can i do to check if it works and how do i know if it is the type that can be used for this project. Resistance on the meter terminals is 7.6kohm and on the light 6.6ohm. I'd post a pic of it but don't know how to do it here.
Title: Slide reply
Post by: W DeMarco on October 06, 2006, 07:30:54 PM
Exactly what I meant by programming the switch.  Check the early pages in this thread for info about the VU meter.  The G1176 board uses 3.6 K on the meter if I remember correctley.  Its the one resistor on the meter switch pcb.  Heres a good vu thread http://www.groupdiy.com/index.php?topic=7628

W
Title: All things G1176 - the new "repost" thread.
Post by: W DeMarco on October 06, 2006, 07:33:52 PM
Also beware of the voltages coming off the meter light output.  You don't want to go through bulbs if its to high for the light you mentioned.
Title: correct part for C6 ?
Post by: gevermil on October 13, 2006, 11:44:44 AM
Anybody know the correct part for the 10V/1WZenor Diode
The parts list # dosent come up on mouser search Yet a bunch of others do ?
I think I ordered the wrong one
Title: Re: correct part for C6 ?
Post by: W DeMarco on October 13, 2006, 12:09:23 PM
Quote from: "gevermil"
Anybody know the correct part for the 10V/1WZenor Diode
The parts list # dosent come up on mouser search Yet a bunch of others do ?
I think I ordered the wrong one



Try this, taken from the parts sourrcing thread  10V/1W ZENER DIODE search 1N4740A at mouser when I did it came up with several options.

Will
Title: All things G1176 - the new "repost" thread.
Post by: gevermil on October 13, 2006, 06:38:50 PM
Yeah .... I wasnt sure which one to pick and in my haste I got a ZM4740A
It dosent have the solder leads
would rat shack have this ?
Title: Zener diode
Post by: W DeMarco on October 13, 2006, 06:51:59 PM
Pretty sure your diode will work.  It claims that its a cross ref for the 1N4740A.  If your nervous about usin it you could order a few of this
 512-1N4740A.
Title: Lorlin Switch Orientation on PCB
Post by: glide 1 on October 20, 2006, 06:00:24 PM
Quote from: "Rob Flinn"
Quote
With the pcb in what I believe the normal orientation/position
how should the switch be orientated/placed in the holes?


It will operate the same in either position.



Ok i searched and read a few posts concerning this but still not quite sure. Is this for the ratio switch and/or is this true for the meter switch aswell?

I noticed however that on mnats' meter pcb, there is an "A" mark, so i assume A on the lorlin leg goes to A marked on the board?.. can anyone confirm this, thanks in advance.
Title: All things G1176 - the new "repost" thread.
Post by: sintech on October 20, 2006, 06:48:03 PM
The lorlin switches will work with any orientation in the pcb, A or B or A, B, C and D types.

If it fits in the holes.. It will work  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: glide 1 on October 21, 2006, 01:38:44 AM
Quote from: "sintech"
The lorlin switches will work with any orientation in the pcb, A or B or A, B, C and D types.

If it fits in the holes.. It will work  :thumb:



Got it, thanks sintech
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on October 24, 2006, 05:26:58 AM
i bought a toroid from avel lindberg---a model that is not on their website (it's 25va) and I thought they said it was 25+25 output...I'm reading that it's 28+28....will this be ok or should I return it?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 24, 2006, 08:26:28 AM
transformers measure different with different load
Title: Rbaker Tran issue
Post by: W DeMarco on October 24, 2006, 09:29:39 AM
RBaker,  go ahead use it,  Sounds perfect!  The whole power supply is gonna treat this voltage and prepare it for the power rail.  And like G said under load your trans will put out differnet voltages.  

Dub
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on October 24, 2006, 02:26:54 PM
oh ok that makes sense.

learn something new everyday!   :grin:
Title: All things G1176 - the new "repost" thread.
Post by: byoung on October 26, 2006, 04:09:56 AM
I am in the final stages of my dual mono/stereo 1176, using mnats boards and psu---- should I just use an spst switch and connect the two "stereo interconnect" pads together for "linked" operation?  Should I use sheilded wire----if so where should I connect the shield?

Also what should I expect once they are connected and the switch is engaged?  Will they just behave like two mono comps with the same signal in the sidechain---ie, I will still have the ability to tweak attack/release on each board separately, or will certain controls affect the other? Which board controls which?

I would love to figure out a way in which when the link switch is engaged that one set of controls could control both L/R channels, I was thinking maybe relays, but seems like I'd need quite a few...any ideas?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 26, 2006, 04:44:55 AM
Quote
should I just use an spst switch and connect the two "stereo interconnect" pads together for "linked" operation?


Look up the information about the 1176SA stereo adapter.

Don't expect too much from the stereo operation - 1176's were never good at that.

Jakob E.
Title: my 1st 1176 working!!!
Post by: glide 1 on October 26, 2006, 05:54:40 AM
Hi all, just like to thank everyone here and most of all Mr. Gyraf and Mnats for a wonderful 1176 project. I now have my 1st 1176 working!! This is also my very first DIY project - so i'm stoked!!

I began to stuff the boards, being very carefull with resistor values especially, double, triple checking everything bofore soldering. Then did voltage checks of the board as to the 'reversed check plot' someone provided. All looked good so proceeded to connect everything up. Mnats' site on wiring the 1176 is so detailed it made wiring a breeze. i fired it up for the 1st time yesterday and much to my surprise - it worked right off....meter, all thr pots, everything!!

After 'calibrating' (not sure if i did this right) I had a chance to use it last night in a session i had recording bass and vocals mainly, and it worked like a charm, all 6 hrs non-stop. My first impression of the sound is that it seems that this compressor rolls off the high freq's a lot, bass freq's a little too but not as much as the highs. Another thing i noticed was with decent levels coming from the pre, i was consistenly at the 3 'oclock (sometimes more) position on the input pot and about the same for output going to my soundcard.

Questions:

*Are the rolloffs in the high frequencies that evident on these units or is there anything i could check on?

*Are my input pot positions (3 o'clock) normal? I also noticed while doing the voltage checks that my voltages were generally about .6-.8V lower than what was on there, could this be perhaps the reason my input seems a little low?

Anyways, i'm very happy with it right now and will probably use it a little more on different sources before doing any major adjustments or anything....

Again, A BIG THANK YOU to all here...



glide 1
Title: Re: my 1st 1176 working!!!
Post by: astrovic on October 26, 2006, 06:34:48 AM
Quote from: "glide 1"
Hi all, just like to thank everyone here and most of all Mr. Gyraf and Mnats for a wonderful 1176 project. I now have my 1st 1176 working!! This is also my very first DIY project - so i'm stoked!!


:thumb: :sam:

Quote from: "glide 1"
Mnats' site on wiring the 1176 is so detailed it made wiring a breeze.


Isn't he a gem?

Quote from: "glide 1"
i fired it up for the 1st time yesterday and much to my surprise - it worked right off....meter, all thr pots, everything!!


Ok, now you're just showing off :wink:

Quote from: "glide 1"
Questions:

*Are the rolloffs in the high frequencies that evident on these units or is there anything i could check on?

*Are my input pot positions (3 o'clock) normal? I also noticed while doing the voltage checks that my voltages were generally about .6-.8V lower than what was on there, could this be perhaps the reason my input seems a little low?


The gurus around here might do with a little more information. Did you go a transformer or non-transformer for the input? If a transformer, which one? What trannie on output?

Happy squishing, man...oh, any pics?
Title: All things G1176 - the new "repost" thread.
Post by: glide 1 on October 26, 2006, 08:32:28 AM
Quote
The gurus around here might do with a little more information. Did you go a transformer or non-transformer for the input? If a transformer, which one? What trannie on output?


Hi Astrovic, ok non-transformer input and an OEP output for this 1. The next one will have both OEP's input and out. I did voltage check it already and i'm seeing the same results as the 1st, lower voltages of about .8V across the board. Is this normal or should i be closer to those on the check plot?

Sorry no pics as of now but will take some when both units are done and i'll post. Man just so happy i got this working. I remember 2 years ago, reading the threads, wishing i could build 1 but was so intimidated not having any electronic skills and knowledge to tackle a project like this.  It was only when i started to build that i got to appreciate ten fold what Gyraf and Mnats have done here, very gateful for that.

I hope my story will encourage newbies and future DIYers who are still on the fence as i was 2 years ago. Just do it, be meticulous about it, check, double check, triple check....If i can do it (of all poeple), so can you!!!  :wink:
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on October 26, 2006, 10:08:00 AM
edit:  
nevermind, I found it earlier in the thread...the ratio changes the threshold. :oops:

I think I'm going to have to try adding that extra trimmer pot.  :)
Title: All things G1176 - the new "repost" thread.
Post by: on October 26, 2006, 11:26:50 AM
I fancy feeding my own PSU into this- so I have taken mnats advice on his website and jumpered allt he PSU connections

However - I want to feed my VU lamp manually and not via the board - so which components on the board can I leave out?

I am taking a uneducated guess at taking out the
10uf
220R
7824
and then jumper the 1k1 1 watt resistor
Title: All things G1176 - the new "repost" thread.
Post by: byoung on October 26, 2006, 02:14:54 PM
Quote
Look up the information about the 1176SA stereo adapter.


So even if I match my FET's I should still use this box? I'm really confused...there are people here on the forum who seem to just use a cable and switch and then others that say to use the box???  Which way is easiest or best or right?

In looking at this box it requires sheilded cable to and from, so I guess I need to find a point at which to ground the sheild of my stereo interconnect link...is this correct?

Also for a stereo unit would it be more beneficial---or even possible--- to control two 1176 boards from one set of pots?
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on October 26, 2006, 05:13:49 PM
I have a question about the attack release pots.  I followed Mnats directions to determin cw/ccw (using the dmm etc) and wired them up.  

The attack and release settings seemed to be "backwards".  I fliped the 2 wires (cw and ccw) on each and thought I fixed it.

Then I just read that I had it right at first---ie: that slow is to the right and fast is to the left.  While that might be the original way, that throws me off.

They are linear pots---can I leave them backwards to save myself headaches or is that going to interfere with something else??

oh yeah...that's CUSTOM! :shock:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on October 27, 2006, 05:44:48 AM
..original units had fast at cw..
Title: Some questions about part for the Mnats G1176.
Post by: API on October 31, 2006, 05:00:17 PM
Hi.

Spent a few hours today in the Farnell catalog shopping for the last parts for my two Mnats boards that i am going to finish this weekend.
But i am unsure about a few things.
Can anyone help??

1. How large power transformer do need?  Is 25va enough?

2. The BC 107´s should these be NPN or PNP.
Also, should they be "just" BC107, or the A or B version??

3. The BC560, these should be PNP, right?

4. Does the 1K1 carbon resistor need to be 1w and 1k1 exactly??
Could only find 1/2 watts in the Farnell catalog, does anyone know a source in Europe?

5. Does anyone know where i can find the 1N4740A Zener diode in Europe?
Farnell did not have that either.

6. The switches, should these be shorting or non-shorting??

Sorry if some of these questions seems a bit stupid, just want to get everything right!

Would appriciate any help, want to order stuff tomorrow!

Regards,
Dennis
Title: All things G1176 - the new "repost" thread.
Post by: louder on October 31, 2006, 05:11:53 PM
alo Dennis
as for the 1k1 resistor,i paralleded two 2k2 resistors.
as for the 1n4740A,musikding.de carries them.
as for the BC560,get the BC560c.
anyway just read all the 1176 pages.there`s everything there.
best regards
pedro
Title: All things G1176 - the new "repost" thread.
Post by: API on October 31, 2006, 05:27:30 PM
Hi Pedro.

Thanks for the info!
Great to paralell two 2k2 resistors, why didnt i think of that!

I am going to read through all the pages, was just looking for some quick answers since i am going to order all the stuff tomorrow and need to go to bed!

Thanks,
Dennis
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on October 31, 2006, 05:56:29 PM
I'm having the same threshold performance as described in this thread by some.   I've seen both possible solutions (extra trimmer to adjust the threshold or the replacement 2n5457 fets)

I just placed an order for the addition trimmer and the fets so I'm planning on messing around with both of them...in the interim, who else has done what? Anyone found either solution to be more effective than the other?

Also are some people just building it stock and not noticing that it's compressing A LOT :grin:  or is it just dependant on the consistency of the fets as jakob has suggested?
Title: All things G1176 - the new "repost" thread.
Post by: imo on October 31, 2006, 10:17:19 PM
I had the best success with the 5457. It increases the threshold a decent amount. Just out of curiousity are you using the input transformer? I have built three of the units, and the only one that had this issue used the Lundahl on the input. The trimmer seemed to work well for a couple of people
Ian
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on October 31, 2006, 11:10:15 PM
yes I am using the lundahl input transformer.  On your others did you use the electronically balanced or the oep?

I really like do like the sound of the unit overall.  Maybe I'll mess around with the oep.  They are cheap, thats for sure.

I tracked vocals and bass for a little while but it just needed more output level.  In bypass there's level FOR DAYS so I know it's just compressing too much.

Will the 5457 change the sound at all?
Title: All things G1176 - the new "repost" thread.
Post by: imo on November 01, 2006, 10:42:24 AM
For more output you can mod the output transformer for 1:2. You can find info on this in this thread.
I used the Lundahl on input as well, also made an electronically balanced version. I have more headroom before compression kicks in on that unit.
Ian
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 01, 2006, 11:55:18 AM
I have mnats board.  I believe it's already wired 2:1
Title: All things G1176 - the new "repost" thread.
Post by: enthalpystudios on November 03, 2006, 02:28:58 PM
Quote from: "dukasound"
OK
Bad english :sad:
I ask this:
If we used Lundahl on out and wired 1:2 or 2:1. Both primary and secondary are wired in series.
On both Jakobs and Mnats boards C15 ? 470uF is connected to minus of Lundahl transformer (pin 1 for 2:1 and pin 10 for 1:2) and plus of windings (pin 4 and can 3 for 2:1 and pin 7 for 1:2) goes to ground.
On Jakobs pcb Bal. Out plus goes to pin 9 who is positive.
On Mnats board (1:2 ratio) Bal out plus goes to pin 5 who is negative.
It is it.


i just checked over the lundahl 5402 datasheets and mnats and jakobs pcb layouts.

my jakob/gustav board doesn't have any labels for -/0/+ on the molex output header, but as they are marked in the pdf file on gyraf.dk, it does appear that the output of the darlington pair drives the (-) output, after the lundahl is all said and done.  a quick flip of the molex would fix that, as long as it doesn't matter whether or not you actually use the (+) markings for windings as indicated on the lundahl datasheet.  i don't see a phase reversal happening there, just at the molex header.

seems to be correct on the mnats board, but i have a feeling that this is just a matter of the silkscreening/labelling, of which there actually isn't any on my jakob/gustav board.

just some thoughts...   so if you use the jakob/gustav layout, it may be a good idea to scope the output pins just to double check which is actually in phase and which is out.


i just realized these things while looking at how to hook up an output transformer off board, as i'm building a pair with b11148 copies, and a pair with ll1517's
Title: Lorlin CK1040
Post by: Magnus Lindberg on November 06, 2006, 12:23:53 PM
Nevermind, I solved it.... :grin:
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 06, 2006, 12:46:57 PM
Quote from: "imo"
I had the best success with the 5457. It increases the threshold a decent amount


I put the 5457's in and finally got around to testing it out.  It definitely helped with the threshold level---I can get a better level out of it, but it's still compressing pretty hard.  

Has anyone listened to the difference?  This might be totally psychological, but I just remember the 245's being a little more....buttery...if that makes any sense.  I'm not going to say that the 5457 sounds bad, AT ALL, I just remember thinking that I'd use the 1176 more than my distressor when I had the 245s in and now I'm not so sure.

I ordered the trim pots, so now I just have to figure out where and how to put them in.  I'm definitely curious if people who are using the oep input are having this problem and just not realizing it?[/i]
Title: Finally found the problem!!
Post by: W DeMarco on November 08, 2006, 03:57:19 PM
So If your searchin for the answer to my problem with the VU pegged meter in GR Mode here it is.

This post started on page 72 and went on for a few pages.  

After I checked voltages on transistors and other places, finding no problems I finally started retracking my interconnects.  If your using the MNATS Boardset, this could be a problem for you.  I found an unused hole labeld 18 next to another 18.  Mnats board version takes many different trimpot sizes.  Hole 18 is set next to a trimpot and connects to it through a trace.  I was using the hole for a larger trimpot, unfortunatley I was using a smaller trimpot.  Ergo, no connection to the trimpot.  

After making this correction GR mode works like a charm.  Thanks for all the help !!  

All thats left is a bit more calibration and this baby ll be in service.  

 :guinness:  :green:  :guinness:
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 09, 2006, 04:20:28 AM
:thumb: Thanks, DeMarco!
Title: Re: Some questions about part for the Mnats G1176.
Post by: API on November 09, 2006, 05:48:57 AM
Hi again.

I think I solved most of my problems, but would love to get an confirmation on some of the stuff.

Quote from: "API"
1. How large power transformer do need?  Is 25va enough?

I bought a 30va toroid, this should be enough, right?

Quote from: "API"
2. The BC 107´s should these be NPN or PNP.
Also, should they be "just" BC107, or the A or B version??

I got the NPN BC107 transistor.

Quote from: "API"
3. The BC560, these should be PNP, right?

Here i am still in the blue.
Someone suggested to get the BC560C version, is this crucial??
And they should be PNP, right??

Quote from: "API"
4. Does the 1K1 carbon resistor need to be 1w and 1k1 exactly??
Could only find 1/2 watts in the Farnell catalog, does anyone know a source in Europe?

I am still looking for this!

Quote from: "API"
5. Does anyone know where i can find the 1N4740A Zener diode in Europe?

Found this.


Quote from: "API"
6. The switches, should these be shorting or non-shorting??

I got non-shorting switches, but i am not sure if they are the right ones.

Thanks,
Dennis
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 09, 2006, 06:34:10 AM
Quote
1. How large power transformer do need? Is 25va enough?

I bought a 30va toroid, this should be enough, right?


yes

Quote
2. The BC 107´s should these be NPN or PNP.
Also, should they be "just" BC107, or the A or B version??

I got the NPN BC107 transistor.


BC107 is only a NPN, that's why we do not specify further.

Quote
3. The BC560, these should be PNP, right?

Here i am still in the blue.
Someone suggested to get the BC560C version, is this crucial??
And they should be PNP, right??


BC560 is only a PNP, that's why we do not specify further.

Quote
4. Does the 1K1 carbon resistor need to be 1w and 1k1 exactly??
Could only find 1/2 watts in the Farnell catalog, does anyone know a source in Europe?

I am still looking for this!


Please read this thread (again?). Yes, it needs to me 1K1, and at least 1W. As suggested several times before, use two 2K2, 0.6W, connected in parallel.

Quote
6. The switches, should these be shorting or non-shorting??

I got non-shorting switches, but i am not sure if they are the right ones.


If it was important, we would have mentioned it. non-shorting are fine.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: jlearman on November 10, 2006, 09:39:14 AM
This is probably a dumb question, but I just built a dual 1176 with the mnats boards (including the separate psu board).  As you know, when you're using the mnats psu, you have to jumper a section on the main board.  My problem is that my VU lights aren't turning on...they're not getting any power from the main board, so I'm wondering if by jumpering the power section of the main board, I jumped the vu lamp output?  If so, what do you guys reccommend for powering the VU and on/off light?  I can I take something off the output of the PSU board (the +30 side, I imagine) If so, what kind of resistor would I need (wattage & resistance)?

Thanks for helping a newbie!  I'll post some pics of the new comp later this week when my front panels arive.
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 10, 2006, 12:41:23 PM
Are you sure the vu lamp isn't getting power?  I'd test it with a dmm to see if there's voltage.

I'm not sure if you used a series resitor when you first hooked up the vu lamp, but depending on the voltage bulb you got, you probably need one.  If you didn't use one, it might have turned on and blown really quickly.  That is something that would have normally happened to me.

But yeah I'd check it to make sure there's voltage (ruling out that the lamp is not working)
Title: All things G1176 - the new "repost" thread.
Post by: gevermil on November 10, 2006, 09:58:44 PM
Can anyone email me  a DETAILED photo of their stuffed PCB board
 :oops:  I know its a cheeseball request , but I made a bone head mistake and burnt a part or two and Im going nuts over this
Any help guys would be great .
G
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 11, 2006, 01:34:18 AM
Gever,

Why is it not enough to look at the component overlay in the layout?

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: gevermil on November 11, 2006, 10:24:34 AM
Thanks Gyraf .
I worked my way back and fixed the problem
 :roll:  Chimay ale sure is strong stuff
Title: All things G1176 - the new "repost" thread.
Post by: Mr. Dave on November 11, 2006, 03:27:16 PM
Would this power transformer work for the G1176, it's 35-0-35.
I'm using the Mnats pcb.
http://www.halted.com/commerce/ccp20783-toroidal-transformer-70-vct-20691.htm
Thanks,
Dave.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 11, 2006, 03:29:24 PM
2x35V is a on the high side - you'd probably be facing problems with too much heat - and probably also with electrolytic voltages. I'd recommend 2x30V maximum.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Mr. Dave on November 11, 2006, 03:34:07 PM
Too much heat from the xformer itself? What  if I used higher voltage caps in the power supply section and had a larger ventilated case?
Dave.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 12, 2006, 02:31:19 AM
Quote
Too much heat from the xformer itself?


No, dissipated heat from the zener and the regulator. Better to stay at 30V max.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: gevermil on November 13, 2006, 12:30:13 AM
So after my recovery from the explosion and fire I am getting good input and output  gain yet no compression . After page searching in this thread I read this -
" I had a similar problem of no compression in my 1176. I used sockets for the bf245a's and i found that the connection was intermittent. When i soldered these parts in it works fine. "
Is this a step I should take ?
Sorry for the lame questions
gary
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 13, 2006, 01:53:52 AM
of course it's possible----but you shouldn't have a problem using sockets, just make sure they are in securely.
Title: All things G1176 - the new "repost" thread.
Post by: API on November 13, 2006, 04:26:30 AM
HI Jakob.

Thanks for the help above!
I was trying to do my homework, but could not find the answers i was looking for.
But now i know!

Regards,
Dennis
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 13, 2006, 04:53:15 AM
:thumb:
Title: All things G1176 - the new "repost" thread.
Post by: Magnus Lindberg on November 13, 2006, 04:37:14 PM
Quote from: "gyraf"
Brad,

Yes, I see that now.

Unfortunately I do not have a G1176 around to experiment on.

A better approach will probably be to install a 100K trimmer pot at the input to the sidechain, as a simple attenuator/voltage-divider (from the top of the output level pot at the ratio subboard) and keep the 56k as-is.

If you try this, please let us know how it turns out!

Jakob E.


Hi

My two G1176's are in the testing stage now before going into rock action. Works great.
BUT
I also think the threshold levels are way too low...not optimal gainstructure at all. The 100k pot sounds like a brilliant idea. I looked at it, and i must say I am not completely sure of where exactly this should be installed despite Jakob's instruction.

Can anyone help?

/M
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 14, 2006, 02:44:04 AM
Magnus,

Look at the schematic - find the place where signal is tapped off for use in the sidechain (around the top of the output level pot). At that spot, simply install the 100K trimmer as a voltage divider to ground, taking sidechain signal off the trimmer's wiper.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: imo on November 14, 2006, 02:51:56 AM
Yes, if looking at the schematic, you take the high side of the 100k output pot to the high side of your new trimpot, the lowside goes to ground, and the wiper(of new trimpot) goes to the sidechain, which would be into R26, the 56k. It is a really helpful modification. Also, using the 5457 fet gives you a bit more headroom
Best
Ian
Title: All things G1176 - the new "repost" thread.
Post by: Magnus Lindberg on November 14, 2006, 02:57:54 AM
Yeeah, it works!

Totally brilliant fix, I raised the threshold by exactly 10dB, much better.Will post pictures soon.

/m
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 14, 2006, 03:39:09 AM
Quote from: "Magnus Lindberg"
Yeeah, it works!

Totally brilliant fix, I raised the threshold by exactly 10dB, much better.Will post pictures soon.

/m


That would be awesome if you could post pictures.  I think I understand but my trimpot has really flimsy legs and I'm wondering how you implemented it without worrying that it would fall apart.
Title: All things G1176 - the new "repost" thread.
Post by: Magnus Lindberg on November 14, 2006, 03:45:35 AM
I actually used a ordinary pot and soldered cables from the ratio board to it. I just gotta find a neat way of attaching it to the bottom plate. Will post pictures tonight maybe.
Title: All things G1176 - the new "repost" thread.
Post by: imo on November 14, 2006, 08:08:58 PM
I wanted to expound on this, as the way i implemented it may be a bit different than others. I mounted the trimmer between the high of the 100k output pot and ground, with the wiper going to the 56k. I cut the trace between 100k out high the 56k, as well as from the 56k to the #15 input (and then rebridged the 100k output pot high to #15) This way the only input to the 56k would come from the wiper of the new trimpot and  allow for control of the input signal to the sidechain. I am assuming this is the only way to do it, as wouldn't the signal simply bypass the trimmer without these changes?
Ian
Title: some lights
Post by: EEMO1 on November 15, 2006, 01:37:13 PM
i got a unit ready. just some finishing touches: lights.

 i got a 12v light for power indication and the meter has got some bulbs (?) in it too. don't know nothing about the lights inside the meter... i can change them to leds if needed.

 where would be the best place to implement these? the vu lamp on the pcb? i can manage the calculations for resistors to make it work, i just need a place to connect them with minimal interference to the circuit.

 any help?
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 15, 2006, 01:43:58 PM
Did you buy a sifam meter or something else?  My sifam meter had 3 choices for lamps.  I got a 12v.  Anyway I think I remember there being 36v from the vu lamp connection, so there's enough for both.  Just calculate the resitance from there, but you need to figure out the specs of the lamp in your meter.
Title: All things G1176 - the new "repost" thread.
Post by: Magnus Lindberg on November 15, 2006, 07:05:23 PM
Quote from: "imo"
I wanted to expound on this, as the way i implemented it may be a bit different than others. I mounted the trimmer between the high of the 100k output pot and ground, with the wiper going to the 56k. I cut the trace between 100k out high the 56k, as well as from the 56k to the #15 input (and then rebridged the 100k output pot high to #15) This way the only input to the 56k would come from the wiper of the new trimpot and  allow for control of the input signal to the sidechain. I am assuming this is the only way to do it, as wouldn't the signal simply bypass the trimmer without these changes?
Ian


I just unsoldered the 56k on the out-pot side, attached the wiper to that and the top to where the 56k was...works fine for me. this way the trim is in series with the 56k.

We might be talking about the same thing but with different words, not sure.

/m
Title: All things G1176 - the new "repost" thread.
Post by: imo on November 15, 2006, 08:00:51 PM
Magnus,
Yes, this is how i did it as well. Makes things more usable!
Ian
Title: thanks!
Post by: EEMO1 on November 16, 2006, 03:23:42 AM
Quote from: "rbaker"
Did you buy a sifam meter or something else?  My sifam meter had 3 choices for lamps.  I got a 12v.  Anyway I think I remember there being 36v from the vu lamp connection, so there's enough for both.  Just calculate the resitance from there, but you need to figure out the specs of the lamp in your meter.


 hey thanks! i figured something like that myself, but wasn't sure about the location. the meter is not a sifam. there were 2 small bulbs in the meter, so i guess it's 3 12v lamps. should i do it in series or parallel?
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 16, 2006, 11:23:03 AM
don't assume it's 12v just because mine is.  Sifam sells 3 kinds, one is 24 one is 12 and one is 6?
Title: no no
Post by: EEMO1 on November 17, 2006, 04:05:06 AM
no, i planned to buy new bulbs. there's 2 bulbs in series inside the meter...
Title: All things G1176 - the new "repost" thread.
Post by: byoung on November 22, 2006, 02:44:16 AM
I just finished up my Dual g1176, it seems as though it is working properly though I have yet to fully calibrate it.  I am curious...I have used OEP in and out on Mnats board and it seems that the unit has about a +6db output ceiling. What I mean by that is that nothing goes over about +6db(haven't measured it yet, just going by my pro tools meter) it's a limiter in the truest sense....no matter how hard or soft I drive the input it limits output to the same range when fully maxed out to 10----about 6db.  Is this right?  I get quite a bit more output from my GSSL and my LA2a so it struck me as kind of low.

Maybe I could reverse my Output transformer for more output or swap a resistor? Anybody know?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 22, 2006, 03:28:54 AM
try calibrating it first. then maybe add the threshold trim mentioned above.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: W DeMarco on November 22, 2006, 09:12:25 AM
Beware of monitoring by ProTools.  O DB ANALOG on my system equals around -14 db DIGITAL.  Remember that you have it set up for headrooms sake.  My G is a bit short on the output but there are several mods concerning this.  One is in current discussion right above your post. I have chosen to leave it be for now and see if its something I can work with.

Will
Title: All things G1176 - the new "repost" thread.
Post by: rbaker on November 22, 2006, 12:22:30 PM
What if you bypass the unit.....is there plenty of gain then?

If so, then you'll want to do the mod discussed above.



I actually have a question about that for jakob or anyone else.

I ended up just replacing the 56k resistor as it was originally described before the trimpot suggestion came up.  I put a socket in so I could change out resistors quickly.  (the trimpot thing, no matter what I did was flimsy...I was going to put in a small perfboard in it but I think this was easier)

I ended up with 560k (10 times the normal) Is there anything wrong with doing it this way as opposed to the trimpot way?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 22, 2006, 12:56:30 PM
Quote
Is there anything wrong with doing it this way as opposed to the trimpot way?


I don't think it can cause any problem..
Title: All things G1176 - the new "repost" thread.
Post by: raysolinski on November 29, 2006, 11:44:22 AM
Okay guys..I need to call in the "big boys"...My G1176 is passing audio..nicely. I can zero the meter and the q bias changes the sound (if I turn the trimmer I can eventually get silence meaning the fet is closed)..but she's not compressing :(..I read this thread and starting hunting...my voltages are way off in the control amp section...I checked and pulled every resistor..made sure the caps were right...Before r70  I have 30.1V After R70 I get 27.4 volts..perfect drop...after r62 I should get 15V or so but I get 25V..I checked r62...put in different verified 47k's....no change...My volts on Q15 are low by 10 volts....I get nothing on r61 (470k) at all..r62 (1meg) has the 25 volts one one side and O on the other....kirchoff's law,  perfectly... but I can't find anything that throws the circuit off by 10 volts...obviously Q12 isn't functioning..it's has no voltage on the collector....could it just be a bad Q12? No shorts around it....??


puzzled as usual..

Ray
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 29, 2006, 01:03:41 PM
Replace parts under suspicion?
Title: All things G1176 - the new "repost" thread.
Post by: raysolinski on November 29, 2006, 04:32:31 PM
I replaced resistors but they all were right to spec anyway..I am waiting for some replacement transistors..I think I will pull the transistors in that section and check voltages..it is almost like I don't have enough , or too much, current..I can't think of how else to explain dropping resistors that don't drop.
27 volts-47k resistor-24.5 volts makes no sense...(and the 47k is verified with two different dmm's)

Ray
Title: All things G1176 - the new "repost" thread.
Post by: raysolinski on November 29, 2006, 08:23:46 PM
I found it! A bad resistor in the gr amp section...put in a new one and voila..I have compression...now I have to bias adjust and set the tracking (which at this point is way off)...thanks Jacob!

Ray
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on November 30, 2006, 02:51:07 AM
:thumb:  :sam:  :sam:
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on December 03, 2006, 08:46:39 PM
Quote from: "rbaker"
Quote from: "imo"
I had the best success with the 5457. It increases the threshold a decent amount


I put the 5457's in and finally got around to testing it out.  It definitely helped with the threshold level---I can get a better level out of it, but it's still compressing pretty hard.  

Has anyone listened to the difference?  This might be totally psychological, but I just remember the 245's being a little more....buttery...if that makes any sense.  I'm not going to say that the 5457 sounds bad, AT ALL, I just remember thinking that I'd use the 1176 more than my distressor when I had the 245s in and now I'm not so sure.



Any more on this :?:

I know that different "Brand" components aren't equal... what brand did you use?

What BRAND 5457 did the "ORIGINAL 1176" use :?:

Thanks,
Kevin
Title: electronically balanced input IC question
Post by: keefaz on December 04, 2006, 01:01:48 PM
Hi,

In the G1176 electronically balanced circuit, I see that
the pin 4 (V-) of 5532 IC is connected to 0V rail and pin 8 (V+)
is connected to 30V rail.

Does that mean that we can power the IC with 0/30V
instead of -15/+15 V ? If yes, why does the manufacturer
datasheet say the maximum voltage is -22/+22 V ?

(sorry for the stupid question :))
Title: All things G1176 - the new "repost" thread.
Post by: joe-electro on December 04, 2006, 01:25:37 PM
Quote from: "khstudio"
Quote from: "rbaker"
Quote from: "imo"
I had the best success with the 5457. It increases the threshold a decent amount


I put the 5457's in and finally got around to testing it out.  It definitely helped with the threshold level---I can get a better level out of it, but it's still compressing pretty hard.  

Has anyone listened to the difference?  This might be totally psychological, but I just remember the 245's being a little more....buttery...if that makes any sense.  I'm not going to say that the 5457 sounds bad, AT ALL, I just remember thinking that I'd use the 1176 more than my distressor when I had the 245s in and now I'm not so sure.



Any more on this :?:

I know that different "Brand" components aren't equal... what brand did you use?

What BRAND 5457 did the "ORIGINAL 1176" use :?:

Thanks,
Kevin


The "original 1176" used a Teledyne FET marked "U2244".  I'm lucky enough to have five original FETs. I've done exhaustive research trying to find any data on this part and the closest I can come is an FET made by Teledyne with the part number "U224-4".  I'm guessing it's the same part.  Point is, to my knowledge, original 1176s never used the 2N5457 (or 5458 or 5459) at all.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on December 04, 2006, 01:27:06 PM
Quote
Does that mean that we can power the IC with 0/30V
instead of -15/+15 V ? If yes, why does the manufacturer
datasheet say the maximum voltage is -22/+22 V ?


Yes, this is quite standard - the opamp dosen't care what we reference the voltages to, as long as it's in- and outputs are kept somewhere between the rails..
 
The -22/+22V simply means that you will have to stay below 44V max.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: keefaz on December 04, 2006, 02:59:41 PM
Thanks Jakob !
Title: All things G1176 - the new "repost" thread.
Post by: Miska on December 06, 2006, 04:45:32 PM
Hi,

can I use Lundahl LL1521 as an input transformer instead of LL1540? Apparently, there is no ground pin on LL1521...

Cheers,
Miska
Title: All things G1176 - the new "repost" thread.
Post by: edanderson on December 06, 2006, 05:11:14 PM
Quote from: "joe-electro"

The "original 1176" used a Teledyne FET marked "U2244".  I'm lucky enough to have five original FETs. I've done exhaustive research trying to find any data on this part and the closest I can come is an FET made by Teledyne with the part number "U224-4".  I'm guessing it's the same part.  Point is, to my knowledge, original 1176s never used the 2N5457 (or 5458 or 5459) at all.


http://jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-1176LNmanual.pdf

if you look at the various 1176 schematics, you can see that they changed from what they called the "DF60214Q" (which was usually a U2244) to the "urei 13-0027" which was either a U2244 or a house selected 2n5457/8/9 type part.   i have a repair bulletin from urei that called for a 2n5457/8/9 as a replacement part for 13-0027, so it could be that most of the 1176s with 2n5457s were ones that had been repaired.

ed
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on December 07, 2006, 03:34:08 AM
Our Rev#F's - purchased around 1987 - came with 2N5457 from factory..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Miska on December 07, 2006, 05:14:03 AM
Bump

Quote
Hi,

can I use Lundahl LL1521 as an input transformer instead of LL1540? Apparently, there is no ground pin on LL1521...



Cheers,
Miska
Title: All things G1176 - the new "repost" thread.
Post by: on December 12, 2006, 03:20:53 PM
I wonder if anybody can help me as I am completely confused and can't figure out whats going on wih my 1176.

It works great as a line amp but I can't get it to compress - did a search and theres lots of advice on how to check points 21 and 19 for Qbias voltage and to check voltage changes according to signal changes - the thing is as soon as I connect my digital multimeter to pins 28 (convienient 0v) and the other probe to either pin 21 or pin 19 the 1176 starts to behave strangely.

By strange I mean the meter (in GR mode which is normally still at 0db) drops to zero and can be moved by moving the release pot to CCW??!?!?

Passing audio through it gives a lower level distorted sound.

Removing the DMM or borrowed oscilloscope probes from the circuit bringsme back to normal operation (albeit without compression which is what I was trying to solve in the first place)

The voltages on the pins that I was supposed to measure  are only moved by the action of the release pot.

So I'm confused - I checked that I have a proper ground and it was ok (getting 0 volts from mnats PSU as welll  as +30 - 10)

SoI'm doing something very basic very wrong - any tips - before I tear out the little hair I have left.

I've built other stuff before - baby animal mic pre, Bo hansen DI, lots of guitar effects but I've never expeirenced this before.

/Taz
Title: All things G1176 - the new "repost" thread.
Post by: keefaz on December 13, 2006, 09:22:05 AM
Just in case, check if pin 18 in the main board is connected to
the QBias trim pot (R81) wiper.
With some trim pots, you have to make a jumper here
Title: All things G1176 - the new "repost" thread.
Post by: W DeMarco on December 13, 2006, 09:45:21 AM
Slow down Buddy,

Dont tear your hair out,  it won't help your 1176,  don't speak to it either, it won't hear you.

I would check all those interconnects and make sure their going to the appropriate spots.  If your using the MNats board there are 2 hole 18's wich accomodate different size trimmers directly next to it.  I was plugged to the wrong hole 18, this played havoc with me for a few weeks.  My G acted horribly until I plugged her to the right hole.  Now its in a rack at the studio!!

It sounds like a bad connection to me.  Make sure your pcb is elevated enough not to ground on the chasis as well.  

Will
Title: JLM111DC for output
Post by: glide 1 on December 18, 2006, 12:50:16 AM
Hi all,

I have built 2 of Mnats' board using OEP A262A2E trafos on both, a little coloured but generally happy with them. I've got 2 more almost fully stuffed and i'de like to use a different trafo for a different "flavor".

I recently emailed Joe at JLM asking him if i could use his JLM111DC on the output and this is his reply:

Our JLM111DC on the output of the 1176 will make a huge difference allowing heaps of headroom and cleaner pure tone instead of the distortion and unbalanced tone of the A262A2E which cannot handle pro level output at all.

So i decided to try this out..  

http://www.jlmaudio.com/JLM111DC_Output_Transformer.htm

Can someone please tell me how to wire this up to the board. I think i've got the secondary output pads on the JLM ok going to the output XLR but i'm not sure which pads to use for the input to the primary of the JLM111DC.
I'm thinking pad "(1)" on the mnats board comming from the negative leg of C15 (the 470uf capacitor) to "+1" on the JLM trafo primary (marked "+ out BA" on the JLM pic above) can someone confirm this please. Thanks in advance


glide 1
Title: All things G1176 - the new "repost" thread.
Post by: mnats on December 18, 2006, 04:43:06 AM
glide 1,

That's correct - with my boards the pad marked 10 and (1) [parenthesis denoting the 2:1 configuration] of the Lundahl LL5402 footprint or S1 of the OEP primary is output of the line amplifier. If you use Jakob's Rev 7 boards use Pin 1 of the Lundahl footprint. Be sure to hook up the transformer's primary to the ground as well. It looks like the -1 pin on the JLM transformer is ground.

Find out from Joe what load resistor, if any, his transformer requires. The G1176 boards upon which mine are based have a resistor, R84, that sits across the Lundahl secondary. This might not be necessary or may need to be a different value for the JLM transformer.

Depending on how you have wired your unit, you may want to return the transformer secondary to the board. If you have wired it as per normal the X and Y pads go to the meter board. Without the secondary connected to the board you will lose your output metering function.

Return the +2 on the JLM to pad 5 of the Lundahl footprint and -3 of the JLM to pad 2 of the Lundahl. This will ensure your meter works correctly. You can wire the output XLR to the BAL OUTPUT pads on the board as normal.

Seems a pity to use a gapped transformer here since no DC gets through the output capacitor, but please let us know how it works in this application when you get it going.

On a side note, have you had any problem with the output levels of your first two units? Joe had mentioned this in another thread but I wasn't too clear on what his criteria was...
Title: All things G1176 - the new "repost" thread.
Post by: glide 1 on December 18, 2006, 05:46:08 AM
Hi Mnats,

Thanks for the reply.

Quote
Find out from Joe what load resistor, if any, his transformer requires. The G1176 boards upon which mine are based have a resistor, R84, that sits across the Lundahl secondary. This might not be necessary or may need to be a different value for the JLM transformer.


I will email joe about this, it will be a week or so befor the trafo arrives but i'm eager to try this based on what he said.

Quote
Depending on how you have wired your unit, you may want to return the transformer secondary to the board. If you have wired it as per normal the X and Y pads go to the meter board. Without the secondary connected to the board you will lose your output metering function.


1:2 was recommended by joe. I have taken note of this too, did not think of the X and Y pads for metering.

Quote
Seems a pity to use a gapped transformer here since no DC gets through the output capacitor, but please let us know how it works in this application when you get it going.


Can you explain this further, i'm not sure what the difference is with gapped transformers. The "headroom, clear tone, and less distortion" part of joe's post is whats making me curious.

Quote
On a side note, have you had any problem with the output levels of your first two units? Joe had mentioned this in another thread but I wasn't too clear on what his criteria was...


I have'nt had any problems with output levels per se but the output pot is almost always at the 3 'oclock position, and more sometimes, to get decent levels to my converters.

I also read that post from joe somewhere saying that the OEP A262A2E saturates very easily. Not sure but he mentioned something about that it is because of its physical size that it distorts easy thus giving that percieved color, having less headroom and so on..

I will definitely post comparisons here when i get everything going.


glide 1
Title: All things G1176 - the new "repost" thread.
Post by: on December 18, 2006, 07:51:10 AM
DeMarcoand keefaz -thanks for your help - it turned out to be a faulty Lorlin rotary on the meter board - prevented the signal continuing over to the ratio board when i GR mode - think I overheated it when i was soldering. So I have 2 1176's in one 2U rack working - and sounding fantastic - going to tidy up some of the wiring.

I'm using Mnats PSU and the -10v regulator gets very warm (i have a small heatsink on it) it hasn't shut down but it's very hot. i'm using the -10v rail after the regulator to power 4 relays for True bypass.

I'm using four omron relays for true bypass and the combined power draw of these is 4x 280mw = 1,12 watt. P=IV so current draw should be I=P/V = 1,12/10 = 0,11 amp. i have a big 50va 24 - 0 -24 torroid. This shouldn't be a problem should it?

/Taz
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on December 18, 2006, 09:38:54 AM
Quote
i'm using the -10v rail after the regulator to power 4 relays for True bypass


Don't do that.

That is about the worst place to draw extra current.

Better to use 48V relays (or coils in series), and power it from the +30 before regulation (there will be some 35-40VDC there)

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: on December 18, 2006, 10:59:29 AM
Ok - i'll try powering them from before the regulator.

/Taz
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 06, 2007, 08:07:31 AM
On page 1 of this thread, a working 1176 had the following measurements:

Q8 14.01 14.61 30.29
Q9 13.94 13.33 0.002

I got this:

Q8 13.61 29.88 14.22
Q9 13.52 0.001 12.92

Is it possible that I've soldered those two transistors in reverse?
Title: All things G1176 - the new "repost" thread.
Post by: King_Cruiser on January 06, 2007, 08:21:33 AM
Index Thread>Meta
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 06, 2007, 09:13:16 AM
It seems that I've forgotten to solder on the two jumpers, the short ones "behind" Q8 and Q9...Actually, I saw them for the first time right now. hehe.

Ok, now the jumpers are in place. No difference, just some slightly higher voltages on all pins of Q8 and Q9.  :mad:
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 06, 2007, 12:34:12 PM
Should I have ~10vDC at pin 2 and 3 to ground on the xlr input? wtf I'm going insane...
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on January 06, 2007, 01:23:38 PM
Quote from: "ChrioN"
Should I have ~10vDC at pin 2 and 3 to ground on the xlr input? wtf I'm going insane...


No, you shouldn't !  Both input terminals are connected to the rest of the circuit by capacitors which should block any voltages to the input XLR. This suggests that you have a short somewhere.

Also have you connected your i/p XLR to the right terminals for the transformeless i/p.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 06, 2007, 01:59:46 PM
I've scratched the back of my head so much, there is a big hole in it now. Luckely I got a calming phone conversation, from a forum member, just in time  :green:   :thumb:

Could it be that I've added some of the *-components? Its not (I think) the ones used for the input transformer option, its the ones Mnats says this about: (quote) The components marked * on the board are optional components not included in the original unit or schematic.

Here is a pic:

(http://i51.photobucket.com/albums/f374/ChrioN/1176.jpg)

Any clues?
Title: All things G1176 - the new "repost" thread.
Post by: mnats on January 06, 2007, 06:32:32 PM
Surely the problem is more likely to be on the solder side of the board. We (and you) would probably know more by having a look there...
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 07, 2007, 03:42:52 AM
Every pin on IC2 (NE5532) has 15vdc except 4 and 8 (pin 4 is ground, 8 has 30vdc).
Ain't that pretty wierd?

They don't short when power isn't applied.

Looking at the schematic, only pin 5 and 3 should have 15vdc (30vdc from the power supply, through the 100kohm voltage divider)

I've also noticed that there is a second "E" hole next to the ordinary "ECB" on Q9. Should I move Q9 a step and try using the second "E" hole instead?
Title: All things G1176 - the new "repost" thread.
Post by: Rob Flinn on January 07, 2007, 06:00:48 AM
Quote from: "ChrioN"
Every pin on IC2 (NE5532) has 15vdc except 4 and 8 (pin 4 is ground, 8 has 30vdc).
Ain't that pretty wierd?

They don't short when power isn't applied.

Looking at the schematic, only pin 5 and 3 should have 15vdc (30vdc from the power supply, through the 100kohm voltage divider)


Maybe the NE5532 is duff !
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 07, 2007, 06:35:40 AM
:oops:

One problem is gone: every transistor DO measure right. I might have had solder smoke poisoning last night, and messed up the values...because now they are all good. (and most definentely was all the time...)
The thing that made me measure again was, that according to last nights measurements, I would have tons of vDC at ground, which I knew I didn't have.

Still, I got issues with the ~12vdc at the xlr input, which seems to be connected with the wierd NE5532 readings...
I've switched ne5532 but I get the same readings

Tips? (and thanks you guys for all the help so far)
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 07, 2007, 09:02:50 AM
I replaced both input caps (better ones, BC), but I still get ~12vdc at the input xlr (pin 2 to ground and pin 3 to ground) It drops slowly, 0.1vdc per 20 seconds or so. Its not "stable" at all.

No shorts between the both soldered legs.

I think this seems impossible. Rule number one is that a (working and healthy) capacitor doesn't allow dc voltage flowing through it. :?

Its like Ethan Hunt is staring this mother.. :green:

I've taken a pic, but the flash of the camera makes the "solderblobs" look like crap, which they ain't.

(http://i51.photobucket.com/albums/f374/ChrioN/11-1.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on January 07, 2007, 09:33:17 AM
Quote
It drops slowly, 0.1vdc per 20 seconds or so. Its not "stable" at all.


My guess it that once you've connected something to the input, the DC will go away. What you see now is input capacitors discharging through your voltmeter..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 07, 2007, 10:26:54 AM
Gyraf: you were 100% right. My unit works great btw  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on January 09, 2007, 04:27:07 AM
My 1176 is now calibrated and works fine. I'll post some pics when I get a nicer looking front panel.
Until then, here is a filmclip of the vu meter in action. (I've not installed the light yet).

The movie is compressed with Xvid. Windows media player is recommended for viewing. Filesize: ~2.5mb :green:

http://hem.bredband.net/b237697/vu.avi

 :sam:
Title: Where to find teh 1N4740A diode in Europe??
Post by: API on February 12, 2007, 12:35:57 PM
Hi.

The only part i am now missing to complete my Mnats G1176´s is the 1N4740A diode.
Does anyone know where i can find one Sweden/Europe??
I have tried the usual places but have only found them in the US so far.

Thanks,
Dennis
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 13, 2007, 04:36:49 AM
..that one isn't present in the G1176 - look at the old layout for reference..
Title: Re: Where to find teh 1N4740A diode in Europe??
Post by: Jim50hertz on February 13, 2007, 05:03:48 AM
Quote from: "API"
Hi.

The only part i am now missing to complete my Mnats G1176´s is the 1N4740A diode.
Does anyone know where i can find one Sweden/Europe??
I have tried the usual places but have only found them in the US so far.

Thanks,
Dennis


PM me an address and i'll send you one
Title: All things G1176 - the new "repost" thread.
Post by: API on February 13, 2007, 06:08:00 AM
Now I am a bit confused!

Quote
..that one isn't present in the G1176 - look at the old layout for reference..


Was this directed to me??
The part is on the Mnats BOM.

Will PM you Jim.

Dennis
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 13, 2007, 09:51:36 AM
Might be the 10V Zener? In Europe we do not have christian-names for the individual voltages like the US-people..?
Title: All things G1176 - the new "repost" thread.
Post by: W DeMarco on February 15, 2007, 04:29:02 PM
I have a Q on my 1176,

I noticed that it has no bottom end compared to my Gssl.  I figure its such a difference that something must be wrong.  I changed to the same wiring that the ssl used out of the patch bays and still had the problem.  I also noticed this same occurence on my almost finished Passive tube EQ.  Again used known good wiring and the same problem.  Has anyone encountered this problem.  I tried searching the forums but can't find anything.  
Thanks
Will
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on February 16, 2007, 04:13:26 AM
probably a balanced/unbalanced issue. gssl is electronically balanced, where the g1176 is transformer balanced.
Title: Point 7 voltage not changing
Post by: lumpylipton on February 27, 2007, 10:33:07 PM
Hi,

I have completed my 1176, and it is passing audio, and I was able to set the Q-bias.  However, my unit does not appear to be compressing.  Looking through the troubleshooting guides here, all my voltages look fine, and my DC voltages are changing at point 21 with ratio changes.  However, they are not changing at point 7.  They jump a bit when I switch ratio, but then they settle back to -1.3VDC.   Also, my VU doesn't work in GR mode (it goes nowhere near 0VU and the zero and tracking doesn't appear to do anything).  The VU works fine in output mode.

Any tips on where to start looking?
Thanks,
Warren
Title: All things G1176 - the new "repost" thread.
Post by: bubba_b on March 01, 2007, 02:12:30 PM
All of a sudden, my 1176 stopped working. It was fine, then the next day, nothing. Here's the problem:

I can see the unit getting input signal and the meter reacting to it, but the output is inaudible. If I crank up the volume on my monitors and set In & Out to full, I can barely hear signal and it is compressing. Any ideas?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 02, 2007, 02:44:21 AM
..output stage and output transformer..
Title: Re: Point 7 voltage not changing
Post by: Holger on March 04, 2007, 12:10:53 PM
Quote from: "lumpylipton"
Hi,

I have completed my 1176, and it is passing audio, and I was able to set the Q-bias.  However, my unit does not appear to be compressing.  Looking through the troubleshooting guides here, all my voltages look fine, and my DC voltages are changing at point 21 with ratio changes.  However, they are not changing at point 7.  They jump a bit when I switch ratio, but then they settle back to -1.3VDC.   Also, my VU doesn't work in GR mode (it goes nowhere near 0VU and the zero and tracking doesn't appear to do anything).  The VU works fine in output mode.

Any tips on where to start looking?
Thanks,
Warren


Same with my 1176. At point 7 I read -1.414V. No compression, passes audio, VU works (quite well) for output. Maybe someone here can give us a hint...please...
Title: 1176 input distortion
Post by: mata_haze on March 09, 2007, 01:26:57 PM
Hi everybody,
I just got my second 1176 ready to be calibrated (the first one is up and running).
I do have a question regarding it which came up while I was trying to set right Q bias.
this is what I have got:
with the unit in bypass mode I can see on my scope a distortion (only on the negative side of the sinewave) when the input pot is set on a position less than half.
so I traced it back and that distortion appears on the input stage right after the input pot on the Drain of the first FET Q1.
all the static voltages look perfect (referred to Jackob scheme) but I can't push the input gain more than 1/4 otherwise this weird distorion appears.
I tried paying about with the Q-Bias settings, but of course that just changes the level at which the distortion appears, but it does not fix it..
any suggestion anyone?
any help will be much appreciated.

BTW= I am using OEP IN and OUT trannies.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 10, 2007, 09:29:07 AM
I've just built a fully working G1176, the problem is there is too little gain. I'm using a lundahl input transformer and a JLM111DC (wired as 1:2) output transformer. Even when the output pot is turned fully CW there isn't enough gain for the AD's on the soundcard. The input on my soundcard is turned to +4dBu btw..

This isn't even one bit higher gain than with a OEP output transformer.

This is how I hooked up the output trannie:

(http://i51.photobucket.com/albums/f374/ChrioN/JLM111DC.jpg)

This problem was solved with the R26 mod: http://www.groupdiy.com/index.php?topic=21491
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 10, 2007, 09:36:10 AM
there should be plenty gain. could be the fet gives too low threshold - see earlier posts about this.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 13, 2007, 04:36:06 AM
There is plenty gain and then some, but only in -10dBv in -10dBv out...but not with +4dBu in and out.
Seems like it starts to compress too early. Is this a "Q bias" issue?
The compressor is useless with input pot turned 12 o'clock or further. Way too much compression
Title: All things G1176 - the new "repost" thread.
Post by: emtee on March 13, 2007, 06:13:12 AM
Look here for posts about resolving the G1176 threshold problems...

http://www.groupdiy.com/index.php?topic=646&postdays=0&postorder=asc&highlight=threshhold+threshold+trim&start=1140
Title: 1176 cant hear it...
Post by: muz on March 14, 2007, 06:26:00 PM
I have a similar type of problem as previous posts...but a little different...
Ive fired it up...everything seems to be working...but I cant hear any compression...
By working I mean...It passes signal...the VU shows the out signal in +4...after tweeking the trim pots, It shows gain reduction in GR mode...and according to the VU the ratio push buttons and attack and release pots work as they should...

Just no compressed audio signal from the xlr output...

So This should make it easier to isolate prob..?

Im using lundahl in and out, mnats rev j and pushbutton boards...

Im a tad green and could do with a couple of hints on this...

Ive been reading heaps of posts...and initially wondered if my imput signal was too low...cause i had to give it heaps of signal to get the GR to meter and set the trims in hard right and left respectivly...
But the more common problem is too much from the input...can I use the  same kind of sidechain/trimpot to fix this?

I suspect it could be the same/related prob..?

please help me on my way...
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 15, 2007, 03:48:42 AM
Quote
Just no compressed audio signal from the xlr output...

So This should make it easier to isolate prob..?


Most of the circuit is working correctly - only you have a problem with the FET at the audio attenuator, or the components just around it.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 15, 2007, 02:59:04 PM
I have 2 problems with my 1176, the first is, the waveform is not centered around "0" when the input pot is used to gain up the signal. Its no biggie, but still a bit annoying.

Here is a screendump of the waveform, you can see that it's clearly "unbalanced":
(http://hem.bredband.net/b237697/waveform.JPG)

The second problem is a bigger one, the unit lacks bass!
I've checked the in and output wiring, everything is good.
I'm using a LL1521 input and a JLM111DC wired as 1:2 on the output.
I don't know where to look :sad:

Here is an audiosample, the first part is the source and the second is the source through a bypassed 1176.

http://hem.bredband.net/b237697/1176.mp3
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on March 15, 2007, 03:17:24 PM
That doesn't sound right :?
I don't have any answers though, sorry.
Title: All things G1176 - the new "repost" thread.
Post by: Arrigotti on March 15, 2007, 05:10:21 PM
I hate to start another troubleshooting thread in the middle of an already existing one, but here it goes.

I am building a Dual Channel G1176.  Both channels pass audio just fine.  One works perfectly.  The other one does not compress, nor does the meter show anything at all.  It will swing all the way right if I turn it to GR mode, and all the way left if it is in Bypass or +4 mode, but the zero adjust does nothing.

I am using the cheap Modutec/Jewell meters from Mouser with the mod than one of the Lab Members described.

I think the problem may be the little goo-covered bridge rectifier that comes with the meter.  In the mod described somewhere in this thread, you have to run the rectifier from the X and Y points on the main board to the X and Y on the meter.

So my question is, if the X and Y weren't hooked up correctly, would you see the symptoms I am having (i.e. no compression, and meter not working)?

Thanks,

Arrigotti
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 16, 2007, 07:05:50 AM
Here is how the low end rolls off. (check my previous post)

I deleted the somewhat nada saying picture and replaced it with a proper frequency respose diagram, some posts down in this page.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on March 16, 2007, 08:01:35 AM
.."roll of point" is somewhat undefined. Comparable figures should rely on -3dB or -6dB points..
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 16, 2007, 08:07:04 AM
this was a bullsh*t post  :oops:
Title: All things G1176 - the new "repost" thread.
Post by: Arrigotti on March 16, 2007, 01:27:51 PM
Quote

 
I hate to start another troubleshooting thread in the middle of an already existing one, but here it goes.

I am building a Dual Channel G1176. Both channels pass audio just fine. One works perfectly. The other one does not compress, nor does the meter show anything at all. It will swing all the way right if I turn it to GR mode, and all the way left if it is in Bypass or +4 mode, but the zero adjust does nothing.

I am using the cheap Modutec/Jewell meters from Mouser with the mod than one of the Lab Members described.

I think the problem may be the little goo-covered bridge rectifier that comes with the meter. In the mod described somewhere in this thread, you have to run the rectifier from the X and Y points on the main board to the X and Y on the meter.

So my question is, if the X and Y weren't hooked up correctly, would you see the symptoms I am having (i.e. no compression, and meter not working)?

Thanks,

Arrigotti
 


Well, I guess I'll answer my own question, which I am actually glad that I can do.

......No silly, look at the schematic!  The X and Y are taken of the main output just to give you signal for the +4 reading.  When the meter is in GR mode, the X&Y are not connected.

(So I say to myself, "Hmnnn, what could be the problem then?"

After probing through volatges, I was able to trace a voltage problem back to the -10V section.  I actually started with the  meter selection switch, and worked my way back from the 28 pad, which had a different voltage than my other 1176.

There ended up being a pad that pulled up right after the rectifier section connected to the -10V.  I fixed the disconnect and all is well.

So I guess the moral of the story is, check all your solder joints, and build up the circuit is sections.

Hope this little issue might help someone else.
Title: All things G1176 - the new "repost" thread.
Post by: khstudio on March 16, 2007, 04:00:55 PM
:thumb:
Title: All things G1176 - the new "repost" thread.
Post by: muz on March 17, 2007, 12:43:00 AM
Quote
Most of the circuit is working correctly - only you have a problem with the FET at the audio attenuator, or the components just around it.

Jakob E.


Thanks for this...

So I replaced Q1 and Q10...it seems that I am now getting compression of audio...but only at maximum compression ratios (all buttons in) and input on full and using my neve pre to hit it with a hot signal...

It seems to me that I need more from the input..?

Ive tested the voltages from scematic...and they seem good...
replaced some resistors...

Im obviously missing somthing...what exactly do you mean by audio attenuator? is this the Q bias trim pot?

Im learning at 100mph...but dont quite know enough to isolate the problem furter...
Title: All things G1176 - the new "repost" thread.
Post by: muz on March 19, 2007, 01:47:36 AM
OK...Ive hooked up a wire so I can touch on points on the board and listen to audio being passed into the input of my 1176...
Should the audio at 1* be about half the volume than before LL1540?

Is the input transformer bung?

anyone?
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 23, 2007, 04:20:40 AM
I've switched the JLM111DC output transformer for an OEP, and now the bass is back. Problem found. This clearly shows that there are components that needs to be changed in order for the JLM111DC transformer to work correctly.
The question is just which component or components. Could this be a load related issue? Maybe change the zobel network resistor?
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on March 23, 2007, 01:03:17 PM
Note: +2.5dB at 5000hz, and -5.5dB at 100hz. Thats almost 9dB.

(http://i51.photobucket.com/albums/f374/ChrioN/111-1.jpg)

Note: I've found the sourse of this wierd frequency response. It is my input transformer, LL1521. I've used the same load resistors as with a LL1540 (12k ohms)
Title: Control section wire
Post by: living sounds on April 06, 2007, 09:39:23 AM
Hi everyone,

I was just starting to hook up the controls for the 1176 and wondered if there is any need to use shielded cable. I couldn't find anything in search or Meta and I'm not a good enough reader of schematics (yet), so: Is there passing audio through those wires or is it only "control data" (like in the GSSL)?

Thanks alot!

Gregor
Title: All things G1176 - the new "repost" thread.
Post by: astrovic on April 06, 2007, 09:47:37 AM
There is audio passing through at some points - have a look at mnats' wiring guide, http://www.geocities.com/m_natsume/1176-wiring.html where he talks about where shielded cable should be used.

FWIW, I used shileded cable on my first build, and didn't on my second, and I have not noticed any appreciable difference.
Title: All things G1176 - the new "repost" thread.
Post by: living sounds on April 06, 2007, 09:49:45 AM
Astrovic,

wow, that was quick! Thank you very much!
Title: All things G1176 - the new "repost" thread.
Post by: syn on April 11, 2007, 01:37:57 PM
Could this   VU be used with germanium diode bridge+resistor for the 1176
project?

Sensitivity (±20%)- 0-500uA   
Resistance  (±15%)-  600Ω
0VU- 270microA

http://www.anders.co.uk/meters_products.asp?prodFamID=2042

thanks
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 11, 2007, 03:28:39 PM
..probably, yes..
Title: All things G1176 - the new "repost" thread.
Post by: syn on April 11, 2007, 05:20:18 PM
thank you
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on April 18, 2007, 12:11:47 PM
This might be a pretty obvious question, but should I calibrate the unit before or after this "mod"?

Quote from: "gyraf"

Look at the schematic - find the place where signal is tapped off for use in the sidechain (around the top of the output level pot). At that spot, simply install the 100K trimmer as a voltage divider to ground, taking sidechain signal off the trimmer's wiper.

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on April 18, 2007, 12:59:58 PM
..it shouldn't matter at all..

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: ChrioN on April 19, 2007, 01:42:07 AM
Thanks alot Jakob
Title: voltage on the board
Post by: maalexx on April 25, 2007, 07:54:05 PM
Hi all,
I'm desperate. I've posted a thread in The Lab, but somebody said me that all things related to 1176 must be here.

Ok. Sorry, but I'm really a newbye.  :roll:
I'm building a couple of G1176 on mnats board rev H.

Anyway, I'm using the onboard PSU. The resistors and components are ok in both pcb's.

In one board, i have +34.7 and -11; in the other board, I have +34.5 and -10.9... it appears to be the same.

I used this transformer:

http://rocky.digikey.com/WebLib/Amveco-Talema/Web%20Data/62000%20Series%20Low%20Profile%20Miniature%20Transformers.pdf

Its name's 62085, digi-key part no. is TE62085-ND. It's 22V 2.272A.

What can I do?
I measured the voltage, then I entirily stuffed the board. Now I'm worried to feed the circuit again, in the case the voltage is too high.
These are the pictures:


(http://www.hitsardinia.com/12.jpg)
(http://www.hitsardinia.com/13.jpg)

From CENTER TAP to either LEFT TAP or RIGHT TAP the voltage is 27.7 / 28VAC, with the transformer disconnected from the board. From LEFT TAP to RIGHT TAP the voltage is 56.2VAC.

There's something going wrong?  :?

maalexx
Title: All things G1176 - the new "repost" thread.
Post by: Purusha on May 14, 2007, 04:31:33 PM
Hello,

I am building two 1176s with Mnats J ver. boards for the first time. One will have OEPs
and another Lundahls... I am trying to understand what ratios should I use here?

I soldered the Lundahl input 2:1 and output 1:2 as suggested in Mnats web page.
One thing I don't know yet, should I use the 10K or 12K for the Lundhals in?

Regarding the OEPs I am not sure what ratios should I use. Any suggestions?
Title: QBias?
Post by: stefan on June 20, 2007, 12:42:13 AM
I´m confused about the "QBias" adjustment, what does "adjusting the trimmer until a level drop of 1dB is achived" mean? Should it say "start with the trimmer fully CCW" or "1dB drop when the unit is turned on" or something like that?
Title: Re: QBias?
Post by: mnats on June 20, 2007, 03:32:17 AM
Quote from: "stefan"
Should it say "start with the trimmer fully CCW"

Isn't that what the manual does say?
Quote from: "UREI 1176LN Manual"

5.3.2 "Q" BIAS ADJUSTMENT...
Q-Bias Adjust = full CCW

I've thought about rewriting the calibration procedure and posting it to my site, but there's nothing in the manual that can be said any clearer IMO.
Title: Re: QBias?
Post by: stefan on June 20, 2007, 01:12:54 PM
Quote from: "mnats"
Quote from: "stefan"
Should it say "start with the trimmer fully CCW"

Isn't that what the manual does say?
Quote from: "UREI 1176LN Manual"

5.3.2 "Q" BIAS ADJUSTMENT...
Q-Bias Adjust = full CCW

I've thought about rewriting the calibration procedure and posting it to my site, but there's nothing in the manual that can be said any clearer IMO.
You are absolutely right, It´s just that I never read the original manual :oops: I just read the instructions on the Gyrafsite.
well that´s how I did it anyway so everything should be fine then. Thanks
Title: All things G1176 - the new "repost" thread.
Post by: Lasselakken on June 27, 2007, 02:58:51 AM
I know this is a bit OT, but I couldn't find a better spot.

I would like to use the Mnats little PSU board to power up a few old modules I'm racking up. If I want to make a +15/-15V supply do I just connect a 2x15V transformer to the mnats psu and tweak the variable resistors to the wished output? And do I do the same for +24/-24 (using a 2x24V transformer)?
Title: All things G1176 - the new "repost" thread.
Post by: dissonantstring on June 27, 2007, 04:09:23 PM
hi Lasselakken,
yes you can.  or use the variable resistor/trim pot option and dial in the exact +/- voltage you need.  
regards,
grant

edit: you could use a 22V-0V-22V xfrmr and still get the +/- 24VDC you need with less heat disapation from the regulators.
Title: All things G1176 - the new "repost" thread.
Post by: Lasselakken on June 27, 2007, 04:53:24 PM
Alright - thanks a lot  :thumb:
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on June 29, 2007, 11:40:10 AM
Hey guys,

I talked to Andrew Brown after purchasing his pushbuttons with mnats pushbutton boards on how to attach them to the rear of the front panel.  He said he uses:

"They are called PEMS and they are pressed in to the aluminium."

Does anyone know where I can get this?  Or a way that I can connect these specific switches?

Thanks so much,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on June 30, 2007, 05:06:24 AM
Quote
"They are called PEMS and they are pressed in to the aluminium."


means that you can't retrofit the switches this way, if your front panel is'nt specially manufactured for this.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on July 01, 2007, 12:22:28 AM
Hmmmm, ok.   Well, is there some kind of a metal bond or glue that I can attach a screw to just so I can make these work somehow??  What are others doing?

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on July 01, 2007, 04:05:10 AM
Countersunk screw through the front plate, and then a "cosmetic" outer-front-plate.

Or try with epoxy glue from the inside

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on July 13, 2007, 04:43:18 PM
Does anyone know what the values of C*, C*1 and C*2 are on the MNATS boards?  Also, where can I obtain the BD135 and BD136 transistors?  Digikey has none, and Mouser lists them, but they're called BD135G ad BD136G, and even these aren't available.  What is everyone else using?

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: josh on July 13, 2007, 11:15:42 PM
Quote from: "Siegfried Meier"
Does anyone know what the values of C*, C*1 and C*2 are on the MNATS boards?  


http://www.geocities.com/m_natsume/1176.html

Read through the wiring guide.  It explains just about everything about this board in great detail, and pictures showing each step.  Very nice.  It will tell you these values and whether you even need them depending on how you are wiring yours.

Always check ebay when you can't find parts.  More than likely you will get a bunch of them for cheaper than you would have bought just the 1 from Mouser or somewhere...

Also, search for your item here and find that you can sub the BD139 and 140 which is what I did, but I'm not finished with mine yet.

Item number: 190131582538 131/135/136
Item number: 170123024244 139's
Item number: 120079340196 140's

It only took me about 5 minutes to write and find all this.....

 :wink:
Title: All things G1176 - the new "repost" thread.
Post by: kazper on July 14, 2007, 12:05:16 AM
Quote from: "Siegfried Meier"
where can I obtain the BD135 and BD136 transistors?


futurlec.com

There $0.20 EA for BD135/BD136 buy a couple bucks worth. You can also use something else on Mnats board (read the docs) BD139 I think? There is a Jumper for the other Transistors.

Note they have 1% MF in under 10 ohm and above 1M Ohm in general. They also have a more expanded 1% MF section for say a 7.68K. There is 4 resistors on the 1176 that call for 1% specific values.

I've had 2 orders from them and everything has been ok. Definitely not as fancy as the other distributors in packaging but it's cheap. Part's have been from Micro, fairchild, TI, Wima, and well who knows. I got lucky on the wima's.


Kevin
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on July 14, 2007, 03:19:51 AM
Thanks for all the help Kazper - here and for the Pultec values.

Now, I've read and reread the 1176 info on MNATS page, and he says:

"The values for the other optional components are listed on Jakob's PDF located at http://www.gyraf.dk/gy_pd/1176/1176.pdf. As the components marked * are not part of the original unit you do not have to use them in order to get a working clone."

I see the values from Gyraf, but I still don't understand, nor can I find, when and why I should use these components.  I'm sure I've missed something, but am I safe to say that I can just leave these out?

EDIT - ok, I've figured out the values from Jakob's original and I understand now, after talking to him that they are there for extra stability.  So I'll stick them in.

Thanks a bunch,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on July 21, 2007, 03:49:04 PM
Alright, the epoxy screw thing is no good.  The stuff never gets quite hard enough, and the screw, or even the nut, always breaks off with even the slightest amount of pressure.

So, here is another way that you could mount these pushbutton switches.

(http://www.siegfriedmeier.com/electronics/Pushbutton%20Mounting%20Alternative%201.jpg)
(http://www.siegfriedmeier.com/electronics/Pushbutton%20Mounting%20Alternative%202.jpg)

Siegfried
Title: All things G1176 - the new "repost" thread.
Post by: Purusha on July 21, 2007, 04:05:45 PM
Using additional panel helps also...

(http://www.tat-purusha.net/2ndpanel.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on July 25, 2007, 03:07:42 PM
Ok guys, this may be basic, but I'm just not understanding this.  I've got the Amveco 62065 for the 1176.  Wiring goes from the IEC, to the switch to the toroid - all is good there.  I've got the secondary wired in series, meaning that the red and brown wires go together to give the 0V, and the blue should give 27V and the green should give 27V, correct?

Now, I've measured, and on one unit I get 27V for the green wire, and nothing on the blue, and the other unit I get 27V on the blue wire and nothing on the green.  Is this normal, that I shouldn't have any voltage on the opposite wire??

EDIT - now none of the leads work.  I've noticed that I've broken off the silver ends, and now only the copper lead is exposed, which, does not allow solder to connect.  However, even just checking the leads, I have no voltage.  Something wrong with the Amveco's?  Perhaps they're not as good as I thought.

EDIT AGAIN - it seems there's a coating on the Amveco leads and not copper.  Have never seen this before on Transformers.  Scraped the coating away, and all is well.

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: Purusha on July 25, 2007, 05:42:33 PM
Quote
EDIT AGAIN - it seems there's a coating on the Amveco leads and not copper. Have never seen this before on Transformers. Scraped the coating away, and all is well.


Happened to me too :shock:  I was also thinking my toroid was gone ... :grin:
Title: --
Post by: gerardmanvuca on July 29, 2007, 09:22:18 PM
---
Title: All things G1176 - the new "repost" thread.
Post by: gerardmanvuca on July 29, 2007, 10:02:27 PM
It's cool , I'm looking at Greg's BOM and it specifies the voltage for each component.

 :idea:
Title: 1176 Thread compressed
Post by: gerardmanvuca on August 05, 2007, 11:33:32 PM
Hey everyone,
I've condensed the ''All things G1176 - the new repost thread'' to 2 pages, if anybody has hard time searching through the whole post, this might
make your life a little easier.

enjoy.

http://www.buythebeats.com/1176%20Thread%202%20pages.rar


peace.
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on August 06, 2007, 04:23:24 AM
Great initiative!!  :thumb:

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on August 31, 2007, 08:17:35 PM
Ok, I finally finished a pair of these and am on to Calibration.  Lots of info, lots of posts and I'm still trying to work out exactly what to do.  However, I have noticed that in +4 mode of my Mnats Rev J versions, I don't get a VU signal (on either unit).  I was under the assumption that +4 was output level, and the +8 was removed and the switch used as an attack off button.  I've checked and rechecked, and I don't think I've wired anything wrong - at least if I did, I did it to both units.

Otherwise, the units seem to be working really well, and no serious noise issues that I can immediately tell.

Thanks for everyone's help on these (too many people to mention), and on the Pultecs as well.  It's taken a while to finish it all, but well worth it.

PS - Gerard, your link doesn't work.

thanks,
Siegfried

(http://www.siegfriedmeier.com/electronics/1176%20Front.jpg)
(http://www.siegfriedmeier.com/electronics/1176%20Inside.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on August 31, 2007, 11:05:55 PM
Also noticed tonight, that along with the VU not working on +4, the second unit I finished, when bypassed, is probably around 5-6 dB quieter than the first unit.  Everything was built identically, with the same lundahl ins and outs.  What would cause the decrease in volume?  Could the input and output pots really have that much tolerance?

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 02, 2007, 12:44:28 PM
Ok, I see now that the Mnats pushbutton boards are reversed, and +4 is actually in the +8 location on the front panel, and +4 is actually GR Disable.  Still have a small level discrepancy, but I think it is just potentiometer tolerance now, as it's not that huge.  Working on calibration, and I realize that I need a real millivolt meter, not just the inexpensive guys for general work.

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 02, 2007, 08:49:16 PM
Hey guys. Need some help getting my G1176's up and going. I built 4 units side by side, and all 4 have the same problem... No compression.
Input and output appear to be working properly. Meter (sifam AL29WF) works properly when set to +4, and it even rests at 0VU when I set it to GR. All voltages seem to match the schematic. I just checked all of the resistors around the ratio switch and everything seems to be in order.
When I check the voltage at the Gate of Q10 with my multimeter, I hear gain reduction, and the meter starts to show gain reduction. When I remove the leads from the gate, the gain reduction stops. And the recovery of gain reduction after I remove the leads even seems to follow the position of the release knob.
I cant imagine it being a solder bridge somewhere since it does the exact same thing on 4 units. It almost seems to be that the threshold is just set too high.
I can get thru the Q Bias adjustment when calibrating, but moving the attack knob to "fast" and adjusting the Tracking pot does nothing. These FETs have been matched using the PRR rig.
Thanks for any help
Dan
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 02, 2007, 09:39:03 PM
Dan,

What exactly is your test and setup procedure? I haven't seen one that requires the attack pot in the 'fast' position (ie fully CW).

Geoff
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 02, 2007, 10:03:13 PM
That sounds pretty odd, and I would say it's definitely something you've done, because you've done it 4 times.  Is the meter completing the circuit somehow, and is it possible you've forgotten to solder something in place?  Just a thought.

I have a strange issue with the output pot on my second unit, and it's not the pot as I swapped it with the good one and it still happens.  It sounds kinda scratchy, and the output level shoots out a burst at over +4 vu, and the speakers just push like mad when it happens - seems like maybe some kind of a DC problem?  Any ideas what to check?

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 03, 2007, 12:12:45 AM
Quote from: "gswan"
Dan,

What exactly is your test and setup procedure? I haven't seen one that requires the attack pot in the 'fast' position (ie fully CW).

Geoff

Hey Guys. Thanks for the replies!
Turning the attack pot CW is actually the 3rd step in doing the tracking calibration (according to the original manual)
-apply 1K and switch meter to +4
-turn output level CW until meter reads 0VU
-turn attack control ON (CW) and observe drop in meter
-adjust input level till meter reads -10

Thats as far as I can get cause turning the attack control ON causes no gain reduction, and neither does adjusting the input level.

Whatever I have done I did in all 4 units. I'm using BF245A FETs... these are the proper ones to use, right? It seems to have the ability to compress but I'm not quite hitting the threshold yet.
Quote from: "Siegfried Meier"
Is the meter completing the circuit somehow, and is it possible you've forgotten to solder something in place?  Just a thought.

Interesting thought... not exactly sure what to look for though. Would the meters actually affect the compression?
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 12:14:38 AM
A scratchy sounding pot is a good sign of DC across it. Check your coupling capacitors (you didn't use tantalums, did you).

Also check your wiring on the ratio switch. If you crossed some of them then it's possible to feed the bias DC onto the output pot.

Geoff
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 12:23:19 AM
Quote from: "dustbro"

Turning the attack pot CW is actually the 3rd step in doing the tracking calibration (according to the original manual)
-apply 1K and switch meter to +4
-turn output level CW until meter reads 0VU
-turn attack control ON (CW) and observe drop in meter
-adjust input level till meter reads -10


Dan, turning the attack pot 'on' means turning it in a CW direction until the switch turns on. BTW, it doesn't really matter what setting the attack pot is at during calibration since we are dealing with a steady-state input anyhow.

Quote from: "dustbro"

Thats as far as I can get cause turning the attack control ON causes no gain reduction, and neither does adjusting the input level.

Whatever I have done I did in all 4 units. I'm using BF245A FETs... these are the proper ones to use, right? It seems to have the ability to compress but I'm not quite hitting the threshold yet.


If you get no gain reduction the you have either not setup the FET into conduction yet (the Qbias step), or your input signal is too low (lower than the threshold) or the input control is too far CCW. Start with the input control at around half way.
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 03, 2007, 01:35:18 AM
Quote from: "gswan"

If you get no gain reduction the you have either not setup the FET into conduction yet (the Qbias step), or your input signal is too low (lower than the threshold) or the input control is too far CCW. Start with the input control at around half way.

I'm sending 1K @ 0dB from a sine wave generator for the Qbias adjustment. Would you suggest sending +6dB or more?
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 01:39:57 AM
No, 0dBu is fine. The threshold is around -20dB. Where's the input pot set at? The input pot needs to be up around halfway or so to  have enough signal at the GR amp to trigger compression.
Title: All things G1176 - the new "repost" thread.
Post by: syn on September 03, 2007, 02:20:54 AM
Quote from: "dustbro"
...and all 4 have the same problem... No compression...
Dan



O.K.,  this is probably not the case, but have you connected your fets  properly (pinout wise)? I've read somewhere around, that if you do that the wrong way ,  audio will still be passed, but no compression will occur...

cheerz
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 03, 2007, 03:28:43 AM
Quote from: "gswan"
A scratchy sounding pot is a good sign of DC across it. Check your coupling capacitors (you didn't use tantalums, did you).

Also check your wiring on the ratio switch. If you crossed some of them then it's possible to feed the bias DC onto the output pot.

Geoff


Which coupling capacitors are you referring to?  I may have used Tantalums, so what would the problem be with that?

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 03:45:50 AM
Quote from: "Siegfried Meier"

Which coupling capacitors are you referring to?  I may have used Tantalums, so what would the problem be with that?

Thanks,
Sig


The stage coupling caps pre and post the output pot. These ensure that there is no DC across the pot.

Tantalum caps are horribly fragile and often fail s/c. If they do you will have DC across your pot.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 03, 2007, 04:10:34 AM
You're referring to C9 and C11, both electrolytic 47 uF/40V, correct?  Those seem to be ok.  I guess next would be rechecking the ratio pushbutton board, which I've done at least a hundred times now.  The answer must just be eluding me.

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 04:18:02 AM
You could measure the DC voltage across the pot and see if there is any. Then isolate the source of the DC.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 03, 2007, 04:49:33 AM
Yep, I've got 8.75 vdc across the output pot pads 15 and 16 (the other unit has nothing).  A little bit of searching reveals that it appears I put C9 in backwards!!

Thanks so much for the help.  This is really the first time I've ever had the chance to use a schematic to search these kinds of problems out, and it feels good to have figured it out.

Thanks again!
Sig
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 05:10:56 AM
That would definitely cause a lot of scratching sounds!

You should check that C9 is still OK. If it's an electro they don't usually like being in backwards. Use an ESR meter to check it or junk it and put in a new one.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 03, 2007, 04:24:40 PM
Yeah, I checked it and it seems fine, but I'll scrap it and put a new one in anyway, while I have it open.

Thanks again!
Sig
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 03, 2007, 09:06:47 PM
Quote from: "syn"
have you connected your fets  properly (pinout wise)? I've read somewhere around, that if you do that the wrong way ,  audio will still be passed, but no compression will occur...

Here's the datasheet for the FETs I got. Looks like it's a direct match.
(http://i101.photobucket.com/albums/m48/dustbro/BF245A_Page_1.jpg)
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 03, 2007, 09:18:44 PM
If you managed to get through the Qbias adjustment OK then the FET is in the correct way around.
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 04, 2007, 12:00:17 AM
now that I think about it, my first mistake may be that I've been setting my meter to VU when doing the Qbias and not Bypass.... well, back to the shop in the morning.
thanks for the help so far.
Dan
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 04, 2007, 12:16:23 AM
I have noticed some things regarding the input and output pots that I just wanted to ask about.  It appears that there is a very sensitive working level that seems to work best.  Outside of this, the unit emits a strange kind of buzz/hum.  For instance, when the output is set to about 12 o'clock - 2 o'clock, and the input is set to 2 o'clock - 3 o'clock, the unit is the quietest, and beyond that this hum and buzz occurs.  Both of my units do it (although not at the exact same settings), so I'm almost simply assuming it is the nature of the circuit and just the way it is.  Can anyone confirm this?

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 04, 2007, 12:28:51 AM
I can't confirm this, since both of my units are quiet over the entire travel of both pots.

Could be PSU or layout.
How much noise are you getting? Even at fully CCW positions?
Title: All things G1176 - the new "repost" thread.
Post by: gyraf on September 04, 2007, 09:34:57 AM
Try moving your power transformer outside the box - If this helps, the hum comes from radiated transformer noise, and can be helped with appropiately shielded wireing and/or box space usage..

If you use the original Gyraf layout - i.e. not the mnats version - be sure to do the macic trace-cuts as mentioned several times earlier!

Jakob E.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 04, 2007, 09:48:54 AM
Using the Mnats boards.  There is zero noise with both input and output pots CCW, only in certain positions for each.  All wiring is shielded with 2 conductor (and 1 shield) mogami wiring.  I'll try the toroid thing, but it doesn't feel like that's the problem.  The fact that both units do it makes me wonder.

Thanks,
Sig
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 04, 2007, 03:29:37 PM
hmmm. I get no action with my meter when it's set to bypass. Is that normal?
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 04, 2007, 03:41:04 PM
Yeah, I'm pretty sure that's normal.  Neither of my 2 units show metering at all when in bypass.

Sig
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 04, 2007, 04:54:33 PM
Quote from: "Siegfried Meier"
Yeah, I'm pretty sure that's normal.  Neither of my 2 units show metering at all when in bypass.

Sig

so... when calibrating the Qbias I assume that I have to use an external meter now? In the original manual it says to have the output cranked all the way up and then adjust input to what you need. On Gyraf's site its a bit more obscure...

[edit]
Ok... while going thru the GR meter tracking on Gyraf's site I see that no matter what I do, I have 5V at my output (measuring between ground and pin 1 of the xlr).
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 04, 2007, 05:59:44 PM
5Vrms? Probably picking up local mains noise (ie it's probably 50/60 Hz).

You should be measuring between pins 2 and 3 of the xlr (ie across the transformer output) since that's where the signal is.

I don't know the version you have constructed, however you should be able to use the meter as stated in the calibration procedure. Bypass mode simply shuts down the GR amp. Are you switching on bypass with the switch on the attack pot or have you put in another switch to do this?
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 04, 2007, 06:04:29 PM
Quote from: "Siegfried Meier"
Yeah, I'm pretty sure that's normal.  Neither of my 2 units show metering at all when in bypass.

Sig


If you are metering GR and switch to bypass, you should see zero GR (ie meter at 0dB). Otherwise you should see signal activity if metering +4 or +8 from the outputs.
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 04, 2007, 06:21:35 PM
Well, I'm using the Mnats pushbutton boards, and I have an original looking front panel.  The way the boards are laid out, it's GR on top, then +4, then bypass, then off.  The front panel shows GR, +8, +4 and then off.  So, at GR I see the meter resting at 0 dB, at my +8 position I see VU level out, at +4 it's bypass, and then off.  A little backwards, but it's fine.  I assume because I don't see level, at Bypass there is no level on the meter.  Yes no?

Sig
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 04, 2007, 07:31:11 PM
I don't have a circuit of that switch module so I'm not sure what the meter is connected to when the GR disable switch is pressed.
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 04, 2007, 07:50:19 PM
Quote from: "gswan"

If you are metering GR and switch to bypass, you should see zero GR (ie meter at 0dB).

If you mean 0dB and not 0VU, then you must use another meter for the Qbias or else the 1176 meter will just rest all the way to the left and just sit there... right?
I'm using Gyraf's 1176 boards over here.
Title: All things G1176 - the new "repost" thread.
Post by: gswan on September 04, 2007, 08:09:49 PM
No, I use the unit's meter to do Qbias calibration. However my switch arrangement is different, since I have the GR disable switch on my attack pot. Are you using the interlocking switch set for metering and GR disable?

Since GR disable just removes the signal to the GR amp, if you press this switch and also the GR metering switch together you should see the GR on the meter at 0 (0VU) since there is no GR. It should not change with signal input until the GR disable switch is released and signal now feeds into the GR amp.

For Qbias calibration, you need to start with the Qbias trimmer fully CCW, which should have the FET turned fully off. Now you need to monitor the signal using the +4 setting and the GR disabled. With the pushbutton switches is may be possible to press both the GR disable and the +4 together to do this. Now apply your 0dB 1KHz signal and perform the calibration.
Title: All things G1176 - the new "repost" thread.
Post by: dustbro on September 04, 2007, 08:22:51 PM
Quote from: "gswan"
No, I use the unit's meter to do Qbias calibration. However my switch arrangement is different, since I have the GR disable switch on my attack pot.

That'll do it
Title: All things G1176 - the new "repost" thread.
Post by: Siegfried Meier on September 04, 2007, 09:20:09 PM
So, can anyone figure out the strange noise/buzz that's happening in both my un