[BUILD] 1176LN Rev D DIY

[dbonin]

Hi leitrim_lad

Please carefully plug the unit in, and as per mnats instructions and CAREFULLY check your DC voltages at the test points on the PCB.
Once that's done, you need to trace the signal - work from the input xlr and make sure signal is getting from there all the way to the PCB.
No point in doing any additional tests until you know your power supply is good and your input signal is getting to the pcb.

Grounding is very important as well - make sure you have done all the continuity tests around the case as mnats has outlined in his step by step guide.

[quote author=leitrim_lad link
=topic=20058.msg707407#msg707407 date=1393681070]
havent connected it to the mains yet as i was waiting to calibrate it before i plugged it in.. is this correct?
[/quote]

 

[leitrim_lad]

Hi there.. i plugged it in originally and checked my power and was getting the correct voltage there perfect.. Ill try plugging it in with the unit completed now shortly and see what i get.. apologies for confusion, i thought you had to calibrate the unit with no power (using the 1k tone) before plugging it in.. doh!!! ;-)

Also the reading i was getting with the 1k tone was between pin 2 and 3 not pin 2 and 0 and pin 3 and 0...

I followed the build instructions to a tee so i checked my power supply voltages 1st before continuing with build and i checked all my earths thoroughly. Even went back last night and re-checked earths twice just to be sure..

checked solder joint and re-soldered any suspect looking ones also..  Checked and doubled checked all my wiring also..

Something i did notice was i was getting a short just after the input transformer on the cable going into the pcb.. is this normal? Isnt in the cable.. seems to be coming from the input transformer itself..


Thanks again

Leitrim_lad

Hi leitrim_lad

Please carefully plug the unit in, and as per mnats instructions and CAREFULLY check your DC voltages at the test points on the PCB.
Once that's done, you need to trace the signal - work from the input xlr and make sure signal is getting from there all the way to the PCB.
No point in doing any additional tests until you know your power supply is good and your input signal is getting to the pcb.

Grounding is very important as well - make sure you have done all the continuity tests around the case as mnats has outlined in his step by step guide.

[quote author=leitrim_lad link
=topic=20058.msg707407#msg707407 date=1393681070]
havent connected it to the mains yet as i was waiting to calibrate it before i plugged it in.. is this correct?

[/quote]

 

[dbonin]

The complete calibration needs to be done with power on, yes. 

Is there continuity between the metal case of the input transformer to the case?  Make sure before going any further.  I have seen lots of issue there.

Just to be sure that your input wiring stage is correct, apply your test signal, disconnect your wires from the PCB where the input is connected and measure AC voltages as you sweep the input knob - you should see signs of life.

Let us know!
-Don

Hi there.. i plugged it in originally and checked my power and was getting the correct voltage there perfect.. Ill try plugging it in with the unit completed now shortly and see what i get.. apologies for confusion, i thought you had to calibrate the unit with no power (using the 1k tone) before plugging it in.. doh!!! ;-)

Something i did notice was i was getting a short just after the input transformer on the cable going into the pcb.. is this normal? Isnt in the cable.. seems to be coming from the input transformer itself..

 

[leitrim_lad]

Hey don, twp i already done that with the input transformer and i was getting a change in voltages when i swept the knob.. Ill test with power now shortly and see im in getting anything at the output..

Thanks a million

The complete calibration needs to be done with power on, yes. 

Is there continuity between the metal case of the input transformer to the case?  Make sure before going any further.  I have seen lots of issue there.

Just to be sure that your input wiring stage is correct, apply your test signal, disconnect your wires from the PCB where the input is connected and measure AC voltages as you sweep the input knob - you should see signs of life.

Let us know!
-Don

Hi there.. i plugged it in originally and checked my power and was getting the correct voltage there perfect.. Ill try plugging it in with the unit completed now shortly and see what i get.. apologies for confusion, i thought you had to calibrate the unit with no power (using the 1k tone) before plugging it in.. doh!!! ;-)

Something i did notice was i was getting a short just after the input transformer on the cable going into the pcb.. is this normal? Isnt in the cable.. seems to be coming from the input transformer itself..

 

[leitrim_lad]

ok so i turned unit on and presto i have voltage correctly at output.. however a new problem.. when i try to adjust the q-bias it doesnt change the voltage.. any ideas? Tried the 2nd way also of putting the meter to +1 and using qbias to drop to 0 and it didnt move the needle either..

thanks again

leitrim_lad

 

[hymentoptera]

ok so i turned unit on and presto i have voltage correctly at output.. however a new problem.. when i try to adjust the q-bias it doesnt change the voltage.. any ideas? Tried the 2nd way also of putting the meter to +1 and using qbias to drop to 0 and it didnt move the needle either..

thanks again

leitrim_lad

There IS a good portion of adjustment where you'll see no movement at all. You're looking for that sweet spot. Explore the full range of movement of the trim pot, some 20 turns I think there is in these multi-turn ones, but be careful not to over-extend and break it.

Also, are you sure the trimmers are installed correctly? If you used the trim pots from Mouser they'll need to be installed perpendicularly to the screen print.

Some ppl need more than 2k and instead install 2k2, 2k5, or more commonly a 5k pot, but I think this is for people who's meter moves too much, not too little. But I could be wrong about this last part.

 

[leitrim_lad]

Cheers for that, will give it a go now and see if i get a change..

Regards

ok so i turned unit on and presto i have voltage correctly at output.. however a new problem.. when i try to adjust the q-bias it doesnt change the voltage.. any ideas? Tried the 2nd way also of putting the meter to +1 and using qbias to drop to 0 and it didnt move the needle either..

thanks again

leitrim_lad

There IS a good portion of adjustment where you'll see no movement at all. You're looking for that sweet spot. Explore the full range of movement of the trim pot, some 20 turns I think there is in these multi-turn ones, but be careful not to over-extend and break it.

Also, are you sure the trimmers are installed correctly? If you used the trim pots from Mouser they'll need to be installed perpendicularly to the screen print.

Some ppl need more than 2k and instead install 2k2, 2k5, or more commonly a 5k pot, but I think this is for people who's meter moves too much, not too little. But I could be wrong about this last part.

 

[leitrim_lad]

Turned the whole 20 turns clockwise and no change unfortunately. . Would I have broken the trim pot?

ok so i turned unit on and presto i have voltage correctly at output.. however a new problem.. when i try to adjust the q-bias it doesnt change the voltage.. any ideas? Tried the 2nd way also of putting the meter to +1 and using qbias to drop to 0 and it didnt move the needle either..

thanks again

leitrim_lad

There IS a good portion of adjustment where you'll see no movement at all. You're looking for that sweet spot. Explore the full range of movement of the trim pot, some 20 turns I think there is in these multi-turn ones, but be careful not to over-extend and break it.

Also, are you sure the trimmers are installed correctly? If you used the trim pots from Mouser they'll need to be installed perpendicularly to the screen print.

Some ppl need more than 2k and instead install 2k2, 2k5, or more commonly a 5k pot, but I think this is for people who's meter moves too much, not too little. But I could be wrong about this last part.

 

[dbonin]

hymentoptera  brings up some great points - common issues there for sure. 

After checking those things try why I describe in this video and let us know how what happens:
https://www.youtube.com/watch?v=9yECKyklD0o

Turned the whole 20 turns clockwise and no change unfortunately. . Would I have broken the trim pot?

 

[leitrim_lad]

OK so another update. .seem to have made it through all the calibrations.. ended up I was being timid with the trim pot, I was afraid of breaking it. Once I turned it more the needle dropped as expected.  No problem with any of the next 2 calibrations either. However when I turn on unit there's a bad hum out of it.. like an earth hum. Checked all my earth's again and they seem to b all perfect.  What's the best way of checking the earth to the input transformer? It's padding signal with this hum, can't really tell if it's compressing. . When I move the output know it seems to be doing strange things also.. bit jumpy or noisy . Any ideas?

Thanks again

Leitrim lad

hymentoptera  brings up some great points - common issues there for sure. 

After checking those things try why I describe in this video and let us know how what happens:
https://www.youtube.com/watch?v=9yECKyklD0o

Turned the whole 20 turns clockwise and no change unfortunately. . Would I have broken the trim pot?

 

[tomas1808]

Hi

Planning on building a mnats 1176 Rev D that would be powered by a x51 PSU (±16V & ±24V outputs).

I know the original PSU gives +30V and -10V. I was wondering if I could use one +24V and a -16V rail to power a 1176.

Would this work? Would I need to make any modification? I dont want to get a DC/DC converter like Don's U76

Thanks!

 

[leitrim_lad]

Hey there so another update.. all hum sorted out. ended up earting the frontpanel by scraping away some paint under the output pot and hum disappeared.. however im getting an awful scratchy noise from the output knob.. here is a link to a recording of it

https://dl.dropboxusercontent.com/u/12155948/1176%20noise.mp3

I also noticed the 1176 seems to be running REALLY hot as in loud.. i have a 6167 and the level of the 1176 on it isnt half as loud as this one.. is that normal?

I also seem to be getting intermittent compression and sometimes none at all on 4 and 8 ratios..

Any help would be greatly appreciated.. I can feel the finishing line hopefully ;-)

Thanks in advance

hymentoptera  brings up some great points - common issues there for sure. 

After checking those things try why I describe in this video and let us know how what happens:
https://www.youtube.com/watch?v=9yECKyklD0o

Turned the whole 20 turns clockwise and no change unfortunately. . Would I have broken the trim pot?

 

[TreyDay]

Hey don thanks fpr getting back to me.. Im on calibration step 1.. iv put on my 1k tone, getting 0.775v on pin 2 and 3 on the input xlr, followed the instructions to a tee (tried both methods) but not getting any voltage on the output pins 2 and 3. my voltage seems to drop to about 0.095v at the point where it connects to the pcb after the input transformer.. I havent passed any audio through it.. havent connected it to the mains yet as i was waiting to calibrate it before i plugged it in.. is this correct?

Thanks

Leitrim_lad

Has anyone else had this problem before? any halp at all would be greatly appreciated.. pulling my hair out checking all res values and everything seems to be good..

Hi leitrim_lad,

Can you give a quick rundown on where you're at with the three calibration steps, please?
Am I correct in thinking you are not passing any audio?

Thanks,
-Don

Sorry for my late reply.

But have you checked all the settings like below?:

Input = “24″ mid rotation
Output = “24″ mid rotation
Attack = full CCW (switched to off position)
Release = full CW
Compression ratio = 20:1
Meter mode = “GR”
Q-bias adjustment = full CCW
Shorting pin in “normal position”  connecting the two pins closest to Q13

Apply a 1 KHz O dBu signal to the input and confirm with your DMM between pin 2 and 3 of the input XLR.  Now move your DMM to the output XLR and measure AC between pin 2 and 3.  Adjust the output control to read +11dBu (2.75 VAC) on your DMM at the output. Slowly turn the Q-bias adjust (R59) CW until a drop of 1 dB occurs, and your DMM reads +10 dBu (2.44 VAC).  This places your gain reduction FET Q1 slightly into conduction.

I got my problem solved I thought it was something with the Q-Bias I didn't set to CCW (I thought 200Ohm).

So make sure your Qbias is correct. And also make sure you are getting the +-0.775VAC on the input. If you are getting this reading move your DMM to the output XLR (pin 2-3 Make sure its in VAC mode) Adjust the output knob on the front of the compressor to read 2.75VAC +11dBu. After you get that readin on your DMM you got to adjust the QBias until a 1dB drop occurs, and your DMM reads +10 dBu (2.44 VAC)

Follow these steps carefully I made my mistake there too. And make sure you triple check everything!!

You could also measure your 2k trimpot to show how many Ohms it's giving. It might be possible that you're turning the trimpot the wrong way. Because it depends on how you installed it.

Good luck bro.

And let us know if this helped.

 

[dbonin]

Are you driving the signal hot on the input? in order to hit the compression ratios the input sometimes need to be hotter than the output - so to speak.

Hey there so another update.. all hum sorted out. ended up earting the frontpanel by scraping away some paint under the output pot and hum disappeared.. however im getting an awful scratchy noise from the output knob.. here is a link to a recording of it

https://dl.dropboxusercontent.com/u/12155948/1176%20noise.mp3

I also noticed the 1176 seems to be running REALLY hot as in loud.. i have a 6167 and the level of the 1176 on it isnt half as loud as this one.. is that normal?

I also seem to be getting intermittent compression and sometimes none at all on 4 and 8 ratios..

Any help would be greatly appreciated.. I can feel the finishing line hopefully ;-)

Thanks in advance

hymentoptera  brings up some great points - common issues there for sure. 

After checking those things try why I describe in this video and let us know how what happens:
https://www.youtube.com/watch?v=9yECKyklD0o

Turned the whole 20 turns clockwise and no change unfortunately. . Would I have broken the trim pot?

 

[leitrim_lad]

Yep was driving the input signal very hot.. it would work for  12 and 20 perfect (compressing heavy) but it didnt work and sometimes was intermittent for 4 and 8..

Are you driving the signal hot on the input? in order to hit the compression ratios the input sometimes need to be hotter than the output - so to speak.

Hey there so another update.. all hum sorted out. ended up earting the frontpanel by scraping away some paint under the output pot and hum disappeared.. however im getting an awful scratchy noise from the output knob.. here is a link to a recording of it

https://dl.dropboxusercontent.com/u/12155948/1176%20noise.mp3

I also noticed the 1176 seems to be running REALLY hot as in loud.. i have a 6167 and the level of the 1176 on it isnt half as loud as this one.. is that normal?

I also seem to be getting intermittent compression and sometimes none at all on 4 and 8 ratios..

Any help would be greatly appreciated.. I can feel the finishing line hopefully ;-)

Thanks in advance

hymentoptera  brings up some great points - common issues there for sure. 

After checking those things try why I describe in this video and let us know how what happens:
https://www.youtube.com/watch?v=9yECKyklD0o

Turned the whole 20 turns clockwise and no change unfortunately. . Would I have broken the trim pot?

 

[rosestudios]

Hi all, first post here,

I've already searched through here and on the internet, but I'm having trouble with the last step of calibration.  I am using the complete Hairball 1176 Rev D kit and as such I was only given two FETs which I were to assume were matched by hairball.  All other transistors have been tested for appropriate hFEs and the meter transistors are within 5% of each other.

I have already successfully performed the Q-bias and Null set, and I can pass audio through and have audible compression.

Can you do this for me please and confirm what readings you get:

1.) Apply a 1 KHz, 0dBu signal, confirmed with your DMM at pin 2 and 3 of the input XLR (0.775 VAC).
2.) Move your DMM to pin 2 and 3 of the output XLR.
3.) Set output control for 0dBu (0.775 VAC) at the output.        <----      (My input sits now at 24 and my ouput at the dot between 48 & 36)
4.) Set attack full CCW (off position) set release to 7 or full CW for fast release. Set the Meter to GR mode.
5.) Set input control for +10dBu (2.44 VAC) at your output XLR.        <---------------- NOTE THAT NOW THE ATTACK IS OFF!! (My input sits now at the dot between 24 & 18, and my ouput knob sits between 48 & 36) (Measuring 2.44VAC on my DMM on the output xlr, pins 2/3)

6.) Turn the attack control ON (full CW) and observer the voltage drop at each of the ratio settings

For each of the ratios, on a rev D, you should be seeing something close to this, shown with attack on:
Ratio:
20 (Att On .788VAC)
12 (Att On .679VAC
8 (Att On .642VAC)
4 (Att on .585VAC)

Hey so I've done an official test here, an analysis would be helpful.  My unit is compressing but I have to pull the output down quite far to get the gain properly for my API 3124s, also there's a bit of noise but not sure if this is the normal level.  I looked through the forum and found that in response to the extreme output trimming, it's meant to act as a makeup gain control so it's ok and someone found noise earlier by using a signal tracer (how would I go about doing this if I were to proceed down this route?  I know how to use a signal tracer but not to find noise).

My results of dbonin's test:

My output is at 48 to get .775 at the output.  My input is at a little above 12 to get 2.44 VAC at the output.

Ratio Results-
20 = .383 VAC
12 = .340 VAC
8 = .333 VAC
4 = .330 VAC

These results appear to be very different from your's, clarification would be great.

Thank you again all, it's been very helpful. 

 

[evanbradford]

First post, so first and foremost, thanks to Hairball and the DIY community for making all these projects available!

I finished my first 1176 rev D yesterday, and it is being used on a vocal, along side a couple of vintage UREIs, as I'm typing this. Sounds phenomenal! The reason for this post is that the only problem is that the release knob is not working. I know 1176s are never super slow, but this one is definitely only functioning with what seems to be the fastest release time and not changing at all when turning the knob. I double checked the wiring and resistor soldered to the pot and it looks correct.  I searched and can't find any info or anyone else that's encountered this, so I was wondering if anyone might have ideas as to what would be causing this.

Thanks!

-Evan Bradford

 

[dbonin]

make sure your release pot it the 5M pot...

First post, so first and foremost, thanks to Hairball and the DIY community for making all these projects available!

I finished my first 1176 rev D yesterday, and it is being used on a vocal, along side a couple of vintage UREIs, as I'm typing this. Sounds phenomenal! The reason for this post is that the only problem is that the release knob is not working. I know 1176s are never super slow, but this one is definitely only functioning with what seems to be the fastest release time and not changing at all when turning the knob. I double checked the wiring and resistor soldered to the pot and it looks correct.  I searched and can't find any info or anyone else that's encountered this, so I was wondering if anyone might have ideas as to what would be causing this.

Thanks!

-Evan Bradford

 

[leitrim_lad]

on closer look i seem to be having the same issue as well.. release time always seems to stay very fast. i also seem to be getting a very high output.. i have to turn the input up to start the compression and then my output know is hardly turned up at all.. is this normal? as i said previous iv got an 1176 off a 6176 and it doesnt seem to be half as loud? any help or thought would be greatly appreciated..

First post, so first and foremost, thanks to Hairball and the DIY community for making all these projects available!

I finished my first 1176 rev D yesterday, and it is being used on a vocal, along side a couple of vintage UREIs, as I'm typing this. Sounds phenomenal! The reason for this post is that the only problem is that the release knob is not working. I know 1176s are never super slow, but this one is definitely only functioning with what seems to be the fastest release time and not changing at all when turning the knob. I double checked the wiring and resistor soldered to the pot and it looks correct.  I searched and can't find any info or anyone else that's encountered this, so I was wondering if anyone might have ideas as to what would be causing this.

Thanks!

-Evan Bradford

 

[Unit7]

Implies that you've mixed up the output and release pots, which was what dbonin pointed out above. Those pots look the same but they are not.

on closer look i seem to be having the same issue as well.. release time always seems to stay very fast. i also seem to be getting a very high output.. i have to turn the input up to start the compression and then my output know is hardly turned up at all.. is this normal? as i said previous iv got an 1176 off a 6176 and it doesnt seem to be half as loud? any help or thought would be greatly appreciated..

First post, so first and foremost, thanks to Hairball and the DIY community for making all these projects available!

I finished my first 1176 rev D yesterday, and it is being used on a vocal, along side a couple of vintage UREIs, as I'm typing this. Sounds phenomenal! The reason for this post is that the only problem is that the release knob is not working. I know 1176s are never super slow, but this one is definitely only functioning with what seems to be the fastest release time and not changing at all when turning the knob. I double checked the wiring and resistor soldered to the pot and it looks correct.  I searched and can't find any info or anyone else that's encountered this, so I was wondering if anyone might have ideas as to what would be causing this.

Thanks!

-Evan Bradford