[BUILD] 1176 Rev A - Back to the beginning...

[blackartmixing]

ok well i am still absolutely no closer to fixing my build.  i have checked the wiring so many times now and cannot find anything wrong.  just to re-cap, i checked all the voltages and all seems ok except maybe Q4

"the only place where is seems to be a bit suspect is Q4.  i get 1.76 on the pin nearest the front panel, 4.18 on the middle and 12.73 on the far pin.  according to the schematic it should be 6.6V and 13.72V so my values seems pretty low"

when i put a signal through the compressor is comes out clean with no distortion.

release and output knobs don't seem to be working as expected

i would like to avoid sending the whole thing back to the USA if possible but i'm running out of options.  is ANYONE able to give me some support here?  i'm desperate!  this forum is really not very efficient although i do appreciate the help so far.  if its not totally clear already i'm a complete noob with this stuff.  thanks

 

[Echo North]

ok well i am still absolutely no closer to fixing my build.  i have checked the wiring so many times now and cannot find anything wrong.  just to re-cap, i checked all the voltages and all seems ok except maybe Q4

"the only place where is seems to be a bit suspect is Q4.  i get 1.76 on the pin nearest the front panel, 4.18 on the middle and 12.73 on the far pin.  according to the schematic it should be 6.6V and 13.72V so my values seems pretty low"

when i put a signal through the compressor is comes out clean with no distortion.

release and output knobs don't seem to be working as expected

i would like to avoid sending the whole thing back to the USA if possible but i'm running out of options.  is ANYONE able to give me some support here?  i'm desperate!  this forum is really not very efficient although i do appreciate the help so far.  if its not totally clear already i'm a complete noob with this stuff.  thanks

Are positive the release and the output knobs are not swapped?

If you send it in for repair, you don't send the whole thing, just the guts.  See here:
http://www.hairballaudio.com/build-support-services

Mike

 

[blackartmixing]

yes unless they are labelled wrong

"the output pot has  A250K on it so i assume that one is correct"

should i swap them over anyway just to check?

another thing about the knobs, they don't really line up very well with the case.  of example the attack pot, fully secured to the case, full CW pointing at 7 and then CCW it clicks off around the 2 mark and end up on 1 and not in the off position i would expect.  also the input and output don't go fully around the dial.  CW at 0 but CWW one dot before infinity. 

 

[tata]

thanks Mike.

* is 29.1VDC enough on the 30V rail when loaded? (w/the VU lamp too) if not which components should i check/replace?

* Q6 is very,  very hot. even with a small heatsink on it. is that totally OK? any good substitutes for that 2N3053?

* can you please link me some info about how to make the 1176 "more symmetrical" in GR? i saw many 1176s doing the same asymmetry, so its not only in my build. those short peaks going thru on one (or the other) phase is not too useful, it just eats up headroom, clipping the next inputs earlier. also on vocals, bass - it can go "flat" on one side and "alive" on the other.
ugly looking waveforms.

* would you please check the Rev.F schemo and tell if that C27 is correctly wired there? (see my previous post / screenshot).

* is there any way to fine tune the distortion as there is in rev. F/G, etc? i know theres no trimmer for it in rev.A, but maybe a resistor?

 

[Echo North]

yes unless they are labelled wrong

"the output pot has  A250K on it so i assume that one is correct"

should i swap them over anyway just to check?

another thing about the knobs, they don't really line up very well with the case.  of example the attack pot, fully secured to the case, full CW pointing at 7 and then CCW it clicks off around the 2 mark and end up on 1 and not in the off position i would expect.  also the input and output don't go fully around the dial.  CW at 0 but CWW one dot before infinity.

The original pots were 320 degree rotation. Modern pots are 295 degrees mostly.  All modern clones are like that. You can't really change the scale.  I line them up in the full CW position to get the classic settings. Line up the attack in the off position.

 

[Echo North]

thanks Mike.

* is 29.1VDC enough on the 30V rail when loaded? (w/the VU lamp too) if not which components should i check/replace?

* Q6 is very,  very hot. even with a small heatsink on it. is that totally OK? any good substitutes for that 2N3053?

* can you please link me some info about how to make the 1176 "more symmetrical" in GR? i saw many 1176s doing the same asymmetry, so its not only in my build. those short peaks going thru on one (or the other) phase is not too useful, it just eats up headroom, clipping the next inputs earlier. also on vocals, bass - it can go "flat" on one side and "alive" on the other.
ugly looking waveforms.

* would you please check the Rev.F schemo and tell if that C27 is correctly wired there? (see my previous post / screenshot).

* is there any way to fine tune the distortion as there is in rev. F/G, etc? i know theres no trimmer for it in rev.A, but maybe a resistor?

1. Yes that voltage is ok.

2. Yes Q6 gets very hot.

3. Asymmetry is awesome. That's color. I think it's beautiful!

4. I didn't design the PCBs, but I'm sure it's fine. If you think it's incorrect you could always alter the PCB.

5. You can always experiment. That's what is great about DIY.

Thanks!

Mike

 

[tata]

4. I didn't design the PCBs, but I'm sure it's fine. If you think it's incorrect you could always alter the PCB.

Thanks!

Mike

Mike,

tho i know this is a rev.A thread, i meant this difference:

is this intentional?

thanks

 

[blackartmixing]

yes unless they are labelled wrong

"the output pot has  A250K on it so i assume that one is correct"

should i swap them over anyway just to check?

another thing about the knobs, they don't really line up very well with the case.  of example the attack pot, fully secured to the case, full CW pointing at 7 and then CCW it clicks off around the 2 mark and end up on 1 and not in the off position i would expect.  also the input and output don't go fully around the dial.  CW at 0 but CWW one dot before infinity.

The original pots were 320 degree rotation. Modern pots are 295 degrees mostly.  All modern clones are like that. You can't really change the scale.  I line them up in the full CW position to get the classic settings. Line up the attack in the off position.

ok i'll do that when its working   so any further ideas to help me troubleshoot this?

 

[Echo North]

yes unless they are labelled wrong

"the output pot has  A250K on it so i assume that one is correct"

should i swap them over anyway just to check?

another thing about the knobs, they don't really line up very well with the case.  of example the attack pot, fully secured to the case, full CW pointing at 7 and then CCW it clicks off around the 2 mark and end up on 1 and not in the off position i would expect.  also the input and output don't go fully around the dial.  CW at 0 but CWW one dot before infinity.

The original pots were 320 degree rotation. Modern pots are 295 degrees mostly.  All modern clones are like that. You can't really change the scale.  I line them up in the full CW position to get the classic settings. Line up the attack in the off position.

ok i'll do that when its working   so any further ideas to help me troubleshoot this?

I'm pretty stumped.  If you want to re-fresh me on the issues (I help lots of people at once and get mixed up) we can start over. How far did you get into calibration?

Mike

 

[Echo North]

4. I didn't design the PCBs, but I'm sure it's fine. If you think it's incorrect you could always alter the PCB.

Thanks!

Mike

Mike,

tho i know this is a rev.A thread, i meant this difference:

is this intentional?

thanks

Look at the PCB.  I think it's just an error on the schematic.

Mike

 

[Spencerleehorton]

Hi,

Been trouble shooting this build for sometime now and have several problems I needed advice for:
+8 on the meter doesn't show any level? GR and +4 show level fine.
Fair bit of hiss on output? Is this normal?
Audio sounds distorted when compressing? Makes funny overload sort of sounds when slammed and fast release attack, audio cuts out for split second!
Null adjust doesn't adjust? Have put MM on R75 and get 0.488v and it won't go down to 0.00v?
Would really appreciate getting some help with this please.

Regards

Spence.

 

[tata]

Spence,

i think the "fair bit of hiss" is normal, ive been asking this too - and seems others have it too. whats your noise level?
Audio can sound distorted, i can confirm - dont push too hard the rev.A (or we both made the same mistakes while building it..)

it was a nice experiment for me, but i think ill stay with the later models (already built a few F/G's).
im not a big fan of the rev.A anymore.

 

[Spencerleehorton]

well I haven't even setup mine properly yet and already I'm preferring the g1176 that I have.
The distortion is really bad when using fast release and attack,  I'm with you I think on moving toward rev d and after.

What is the difference between the Rev A and Rev D?

Ah I've just had a look, the preamp is different, 1 extra transistor, and the FET replaced with a transistor, a few values are different.
Has the Rev A pcb been successfully modded to a Rev D?

 

[Echo North]

well I haven't even setup mine properly yet and already I'm preferring the g1176 that I have.
The distortion is really bad when using fast release and attack,  I'm with you I think on moving toward rev d and after.

Hard to say if that's the normal rev A FET saturation charm or something more.

If you look at the later Revs there is a 10K resistor that sits between the source of Q1 and GND.  You can add that and it should tame that saturation of the FET. If that's what you're hearing.

Mike

 

[Spencerleehorton]

I suppose it's possible to put some more trimmers in to achieve these mods, the at least if I want to dial in some more distortion I can.
What the main difference between using the j309 as apposed to the 2n3391?

 

[Spencerleehorton]

Going to get the Rev A running as good as I can then I will do a little break out board and change values to Rev D. I count 30 components to change.

 

[Echo North]

I suppose it's possible to put some more trimmers in to achieve these mods, the at least if I want to dial in some more distortion I can.
What the main difference between using the j309 as apposed to the 2n3391?

Those are completely different types of transistors. One is a JFET one is a BJT. You can't just switch those.

I would just put a 10K resistor between the Q1 source lead and ground. Start there.

mike

 

[JulienB]

Hi, I finish the build, there is my voltage, cant you help with some tip, for calibrated the unit. Actually, it is not possible to calibrate the Zero ajust for 0.0 Volts across R74.
Thanks
JB

 

[Echo North]

Hi, I finish the build, there is my voltage, cant you help with some tip, for calibrated the unit. Actually, it is not possible to calibrate the Zero ajust for 0.0 Volts across R74.
Thanks
JB

The Rev A you measure across TP10 and TP 11, not R74.  See the guide:

http://www.hairballaudio.com/blog/resources/post/calibration

Mike

 

[JulienB]

Hi, I finish the build, there is my voltage, cant you help with some tip, for calibrated the unit. Actually, it is not possible to calibrate the Zero ajust for 0.0 Volts across R74.
Thanks
JB

The Rev A you measure across TP10 and TP 11, not R74.  See the guide:

http://www.hairballaudio.com/blog/resources/post/calibration

Mike

Sorry, yes across TP10 and TP11. It is not possible to have a 0,00v?
You cant see the attachement, they have all my voltage. In the Gr meter drvier section everything good. But, in the Gr control amp I have significat difference. Cant you help