[BUILD] 1176LN Rev D DIY

[Echo North]

Yes Q1 and Q11 on the A/D and Q1 and Q10 on the F/G or matched by me.

Q12 and Q13 are matched by the user.  See here:

http://www.hairballaudio.com/blog/d_assembly/revd/populating-the-pcb/

 

[the groke]

Ah, OK. I suppose it was Q1 and Q11 that came pre-measured. But I did match one pair - I forgot that it was Q12 Q13. I picked the two closest values after checking for a lot with a high enough HFE for the other functions. Sorry for spacing on this a bit. Whether or not my meter is accurate enough to have done a good job with HFE is another question I suppose. I do remember that the values were not exactly steady - they drifted around a bit. That probably is not a good sign, right?

I think I will borrow someone else's meter and redo those two transistors. If I change them, will I need to redo all the earlier calibration steps?

Thanks - D

 

[Echo North]

Ah, OK. I suppose it was Q1 and Q11 that came pre-measured. But I did match one pair - I forgot that it was Q12 Q13. I picked the two closest values after checking for a lot with a high enough HFE for the other functions. Sorry for spacing on this a bit. Whether or not my meter is accurate enough to have done a good job with HFE is another question I suppose. I do remember that the values were not exactly steady - they drifted around a bit. That probably is not a good sign, right?

I think I will borrow someone else's meter and redo those two transistors. If I change them, will I need to redo all the earlier calibration steps?

Thanks - D

I should only change the meter calibration.  Never hurts to recalibrate though.

 

[the groke]

OK, thanks.

I sent pics of my front panel buckling to your email account.

best,

D

 

[the groke]

Hm…. both of my 2n2708 transistors (Q12 and Q13) were matched pretty nicely ~321 HFE. I swapped in another pair anyway. Same problems as before. I can't bring R44 up to -10.

I'm going to try a 5k pot in R71, not that I really understand why it would even help…

D

 

[deveng]

Just completed the first build for two of my 1176's last night.  Everything worked first power-up and the calibration was completed without a hitch.  Ran it through RightMark analyzer and measures were all good (a bit better than the specs in the original manual).  I just have a mocked up front panel for now so I won't post any pictures.  Since its just another of many it isn't much different anyway.  I built the rotary version using the Rev. D boards.  I've also got the stereo link boards installed.

The trick, I believe, with this build (or any kit build for that matter) is careful attention to all build details "as you go".  Its easier to spend a little extra time to make sure each part is correctly installed and wiring is right.  There's no reason it shouldn't work if this is done.  Circuit debug after the build is not always an easy task, especially for someone not experienced doing it.  Mistakes may be made, and I've made some,  but taking the extra time will usually save you headaches later.

Hats off to Mnats & Hairball for their efforts to document all steps of the build.  Nicely done gents!  Now its time to make some music.

Regards,
Jeff

 

[Fenderbender]

Hi guys.... I have the same problem as The groke... No matter what I do, it seems impossible to do the 3 and final step.. The other to steps Went Well... I swapped the 2 k trimpot (r44)with a 5 k... It didn't help. Voltages according to the schematics  provided by Mnats are within 10%. I read in another post that if you turn the input and output up to 12 o'clock, then you Should be able to messure 2.75vac at pin 2 and 3 on the output, and if you turn the input up higher Then up to 10vac. I get 5.88 vac in the 12 o'clock position and if I max the input i get 28.8vac... It distorts and pops like crazy. I Can get the compressor to work, but I really have to be careful with the input... I like distortion, but not that kind...
To sum things up: impossible to do the last calibration step and it distorts pretty quickly.
Hope that someone have an idea, because i'm lost...

 

[the groke]

AHHHHHHHHHH - FINALLY - IT WORKS!!!!!!!

I'm insanely happy right now. Why does it now work? I don't really know…. My only obvious mistake out of this entire build was the red/orange wire mixup…

But, I did actually go back and redo all of the calibrations. One thing I noticed was that on the Q bias step, it is really tricky to get the trimmer to settle into the correct value. When I just barely passed the sought after value, going back a hair on the pot did not bring the value back a hair - rather, I had to go a number of turns back - very strange. I have no idea if this sort of response is normal. Perhaps my unit was still warming up? It is possible that this my issue the whole time (maybe I was too hasty on the first round of calibrations). I'm not sure. Anyway, it works… I'm not going to question it

Hairball's new calibration instructions on his 1176 page are super clear and effective. Thanks SO MUCH for updating step three in particular.

And a big thank you to everyone else who offered suggestions.

Fenderbender - I'm obviously not the one to look to for good answers - but if you haven't seen the instruction updates, go to the hairball site and check them out.

I'm still curious if something can be done about my buckling front panel. Mike/Hairball, did you get the pics I sent OK?

-D

 

[rafta]

Hi everybody
I'm building an Hairball kit but I have some trouble with 1 resistor.
I have a resistor of 570 ohms on my attack potentiometer instead of a 470 ohms.
It can be a problem?
Thank you
Rafta

 

[hymentoptera]

Hi everybody
I'm building an Hairball kit but I have some trouble with 1 resistor.
I have a resistor of 570 ohms on my attack potentiometer instead of a 470 ohms.
It can be a problem?
Thank you
Rafta

I can't imagine where in the world you found a 570R resistor, but the 470R is a very common part, and any wattage or tolerance will do. Try to keep it within 5% of 470.

With too high of a value at R54 I would expect slightly slower attack time, probably most noticeable with attack fully clockwise (fastest), you might not attain much faster than 50μS attack, but I must admit I don't fully understand what's happening at that point in the circuit. Perhaps someone else could explain exactly what the wrong value at R54 will do.

 

[EstockAudio]

With input and output set at noon with a 0dB signal feeding the input I'm getting 8.28V AC!  Increasing the input doesn't lower the voltage.  I've checked everything with the schematic and can't find an issue. 

If your GR off is ok, did your bias go well?

The Q-Bias step went fine.  Step three is where things got quirky.

With the input and output at 12 o'clock and GR OFF.  what are you seeing between XLR output 2 and 3 feeding a 0dB signal into the input?  You should see something like 10dBu ish which would be about 2.25V AC.  If you continue to crank the output to max you should see as much as 10V.  If increasing the input lowers it your GR OFF in not working. 

Otherwise your gain stage is messed up and we'll start exploring down that road.  Start by checking agains the schematic with voltages on the MNATS site.

Mike

 

[maxathys]

1176 (hairbal) Rev D Calibration step 3 no drop, on any of the 4 ratio settings

I passed the calibration step 1 & 2.  But I have no drop in step 3. when I turn the attack button from off to fully CW nothing happens, (tested on the 4 ratiosettings). I've triple checked the wiring. On the first eye the pcb looks fine too. Does someone know where to look? I've no idea where to look.
(the tracking trimpot works: tested with my DMM). So my compressor isn't compressing :/

+ is it normal that i can actually hear the 1khz tone in the compressor when pushing the output and input?   (i think its the output transfo, not sure though)

thx in advance!!

 

[deejaywhite]

Hi,

I've built the Power Supply in about 4 hours, soldered clean and with care

When I want to measure the R87 with the beginning of the pcb, I measure 45V in place of 30V (CR6 measures -9,7, which is ok!)

Does this has something to do with my Rectifier, where a capacitor isn't working? (noted that I have the right transformator)

I triple tested all my components before and after soldering and everything worked perfectly...

Can someone please help me, I'm pulling my hair out for 48 hours now...  :-[


THANKS!

 

[EstockAudio]

You and I are having the EXACT same issue.  I can hear the 1K tone when pushing levels as well.

1176 (hairbal) Rev D Calibration step 3 no drop, on any of the 4 ratio settings

I passed the calibration step 1 & 2.  But I have no drop in step 3. when I turn the attack button from off to fully CW nothing happens, (tested on the 4 ratiosettings). I've triple checked the wiring. On the first eye the pcb looks fine too. Does someone know where to look? I've no idea where to look.
(the tracking trimpot works: tested with my DMM). So my compressor isn't compressing :/

+ is it normal that i can actually hear the 1khz tone in the compressor when pushing the output and input?   (i think its the output transfo, not sure though)

thx in advance!!

 

[Echo North]

Audible tones can happen when the output is loud enough.

No Compression, but passing signal:

Something is wrong with your side chain.  Things that can cause this:

- Improper QBias adjustment.
- Component error on the Ratio PCB
- Component error on the Attack/Release Pot
- Component error on the side chain section of the PCB
- Wiring between all of those parts.

After checking all of that troubleshoot.

Troubleshooting:
Feed a 1K 0dB signal into the compressor.  In/Out/Att/Rel all set half way. Confirm that you see 0.775 VAC between input pin 2 and 3.

Post your AC voltage between pad 22 and ground for:
20:1 -
12:1 -
8:1 -
4:1 -

Post your DC voltage between pad 21 and ground for:
20:1 -
12:1 -
8:1 -
4:1 -

Post your DC voltage between pad 19 and ground for:
20:1 -
12:1 -
8:1 -
4:1 -

Mike

 

[maxathys]

First off all, Thx for the fast reply!! great service! 

I checked the components on the ratio pcb and i noticed something strange, all the resistors decreased in Ohm.
Also I can't check R5 because my DMM only goes to 2000k.

Component error on the Ratio PCB

1.  146 ohm 2.  432 ohm 3.  510 ohm 4.  1164 ohm
5 cant measure 6. 49,7k ohm 7.  49,8k ohm 8.  58,8k ohm

9. 42k 10. 49k


- Component error on the Attack/Release Pot

452 ohm Cant measure caps


224k ohm


What is the sidechain section of the PCB??

 

[dbonin]

First off all, Thx for the fast reply!! great service! 

I checked the components on the ratio pcb and i noticed something strange, all the resistors decreased in Ohm.
Also I can't check R5 because my DMM only goes to 2000k.

Component error on the Ratio PCB

1.  146 ohm 2.  432 ohm 3.  510 ohm 4.  1164 ohm
5 cant measure 6. 49,7k ohm 7.  49,8k ohm 8.  58,8k ohm

9. 42k 10. 49k


- Component error on the Attack/Release Pot

452 ohm Cant measure caps


224k ohm


What is the sidechain section of the PCB??

Checking resistors in circuit is going to give you readings that are off the mark - google will explain why. 

To add to Mikes suggestion, check the component values using the color codes on the resistors to visually verify they are correct - for other components just check the values printed on the part.
If you have to check a resistor you'll need to de-solder one leg before testing.
I would do it visually first then take the measurements Mike suggested for the different ratio settings. 
It is unlikely that a resistor is "bad", but highly likely one is incorrectly placed somewhere - if it is related to that at all...

 

[Echo North]

What is the sidechain section of the PCB??

Labeled "Gain Reduction Amp" I believe.

 

[Echo North]

Also there is a good bit of wiring to and from the sidechain that can be messed up.

 

[maxathys]

Okay So i checked the whole GR control amp section, the ratio section, the wiring, everything was okay, so i re-did the calibration and
suddenly I have a -17 drop with the calibration, but the r44 trimmer does nothing to get it on -10db drop. 

Note; I think there is something wrong with the T input attenuator. its very sensitive, when i move for example from -48  to -36db my VU meter jumps into full red (in VU mode) all the time while  i only moved it for 12db. but when i give a little knock to it its back normal. I think this might be the problem, when the t attenuator is in error mode there is no jumping, when i knock it it jumps again to -17 db with the 3th calibration step.
So i think it was in error mode when i did the calibration and i lowered the output till it was on 0db on the vu meter, thats why it didn't move (I think).

So forget the previous problems.

New problems:

unstable t attenuator, and r44 is doing nothing.

Thx guys for helping me out!!