[BUILD] 1176LN Rev D DIY

[RuudNL]

Did somebody ever measure the distortion at 40 Hz, with a gain reduction of 4 or 5 dB?
With a bass guitar I get audible distortion, even at longer release times.
Just curious...

(In the 'off' position, - so with the signal going through the circuit-, the distortion is very low.)

 

[Echo North]

Did somebody ever measure the distortion at 40 Hz, with a gain reduction of 4 or 5 dB?
With a bass guitar I get audible distortion, even at longer release times.
Just curious...

(In the 'off' position, - so with the signal going through the circuit-, the distortion is very low.)

I can do it, but it'll be a 1-2 weeks as our units are on loan at the moment.

Mike

 

[RuudNL]

That would be very kind of you!
No need to hurry anyway.
I can't imagine that it is a problem of my 1176.
I passes 'average audio' without any problems, (lots of headroom!)  but with bass-only signals I can hear distortion.
Also I noticed that the release time, even at the longest setting, must be rather fast, judging by the movement of the gain reduction meter. (Meter is calibrated and indicates the actual gain reduction.)

Many thanks in advance for your help!

 

[babaorum]

I had an  output signal's level pb that I solved (replace the wrong R9 = 56 k by the good one R9 = 560 k  8)).

Now I try to do the calibration.

But I can have 2.75V at the output but trim R59 (qbias) in all the route doesn't change the value so I can't have 2.44V (-1 dB) by the trimmer ....
Somebody told me to replace the 2k trim by a 5k do you think it could be cause that ? (at this time this is the 5k which is on pcb.)

Could you help me ?

Thanks,

Baba

Absolutely don't change the trimmer. If you can't get the 2K QBias to work something is wrong with your bias circuit.

Referencing 0V/CT what is your DC V at:
1. Either side of R35
2. Either side of  R60
3. Pad 18 when you turn the Qbias what is the highest and lowest?

Mike

R35 :  -9.6  /  -4.1
R60 : -4.1  / 0.0
Pad 18 : min=-4.1 max=0.0 (with trim 5k -> 25 laps between the two values)

Thanks for help .

 

[Echo North]

I had an  output signal's level pb that I solved (replace the wrong R9 = 56 k by the good one R9 = 560 k  8)).

Now I try to do the calibration.

But I can have 2.75V at the output but trim R59 (qbias) in all the route doesn't change the value so I can't have 2.44V (-1 dB) by the trimmer ....
Somebody told me to replace the 2k trim by a 5k do you think it could be cause that ? (at this time this is the 5k which is on pcb.)

Could you help me ?

Thanks,

Baba

Absolutely don't change the trimmer. If you can't get the 2K QBias to work something is wrong with your bias circuit.

Referencing 0V/CT what is your DC V at:
1. Either side of R35
2. Either side of  R60
3. Pad 18 when you turn the Qbias what is the highest and lowest?

Mike

R35 :  -9.6  /  -4.1
R60 : -4.1  / 0.0
Pad 18 : min=-4.1 max=0.0 (with trim 5k -> 25 laps between the two values)

Thanks for help .

That all looks good.

What is the min/max V DC at the Q1 gate when you rotate the bias?

Mike

 

[babaorum]

Stay always to 0.00 

Does it mean Q1 is dead ?

 

[useme2305]

quick question: is there any way to make the GR meter work for multiple buttons in?

i built a revD and it sound amazing on vocals with ratio 4+12. dialing it in by ear is fine. i just wish the meter worked.

 

[Echo North]

Stay always to 0.00 

Does it mean Q1 is dead ?

Hmmm if it was at 0 V DC you could not get 2.74V AC at the output.  Sure you're measuring DC at the Gate?

Mike

 

[Echo North]

quick question: is there any way to make the GR meter work for multiple buttons in?

i built a revD and it sound amazing on vocals with ratio 4+12. dialing it in by ear is fine. i just wish the meter worked.

No, that the way the original is as well. Part of the secret!

 

[babaorum]

Stay always to 0.00 

Does it mean Q1 is dead ?

Hmmm if it was at 0 V DC you could not get 2.74V AC at the output.  Sure you're measuring DC at the Gate?

Mike

yes I'm sure. I ordered 6 new 2N5457, as I plugged them on connector's supports I will be able to replace them as I want.

 

[Echo North]

I'd double check your attack/release/ratio wiring as well.  That get's the Qbias voltage from that trimmer to the gate.

 

[babaorum]

Do you want I give photos of them ?

 

[babaorum]

I just checked the ratio pcb , all seems ok excepted :
- the release cable is deconnected I don't know if it's when I unplugged the Ratio knob from the box.
- the R45 10M resistor show 0.00 to my Multi
- the R57 270k show values immediatly decrease to 0.00
- Only 19 and 4 are connected , I didn't connect the other OUT POT on this side of the pcb (15,16,17,OUT,POT) maybe there is a reason I didn't remember ...

 

[Echo North]

I just checked the ratio pcb , all seems ok excepted :
- the release cable is deconnected I don't know if it's when I unplugged the Ratio knob from the box.
- the R45 10M resistor show 0.00 to my Multi
- the R57 270k show values immediatly decrease to 0.00
- Only 19 and 4 are connected , I didn't connect the other OUT POT on this side of the pcb (15,16,17,OUT,POT) maybe there is a reason I didn't remember ...

Resistors are effected by other parallel circuits. What do you mean the "release cable"?

 

[Echo North]

Do you get a -DC V at pad 7? Does it change when you rotate qBias?

 

[babaorum]

What do you mean the "release cable"?

One of the release cables which are connected between release knob and the ratio pcb.

Ok I will check pad 7;

Thanks

 

[opkacz]

Hello everyone,

I have just finished building a Hairball Audio 1176 Rev D rack compressor and finished the calibration process. Everything is working properly with the exception of the Release knob which seems to have no effect whatsoever. The unit sounds good and I am almost positive that everything else is working correctly so how should I go about troubleshooting this issue? Thanks for your time!

 

[Echo North]

Hello everyone,

I have just finished building a Hairball Audio 1176 Rev D rack compressor and finished the calibration process. Everything is working properly with the exception of the Release knob which seems to have no effect whatsoever. The unit sounds good and I am almost positive that everything else is working correctly so how should I go about troubleshooting this issue? Thanks for your time!

The release or attack? The attack has little effect with it's 20-800vmicro sec timing.  If the release is not working, make sure that is indeed the 5M pot and it's wired correctly.

Mike

 

[RuudNL]

Just a reminder, in case you have a unit available!
FET bias is adjusted correctly, I suppose the distortion occurs because of a superimposed ripple on the control (gate) voltage.

Did somebody ever measure the distortion at 40 Hz, with a gain reduction of 4 or 5 dB?
With a bass guitar I get audible distortion, even at longer release times.
Just curious...

(In the 'off' position, - so with the signal going through the circuit-, the distortion is very low.)

I can do it, but it'll be a 1-2 weeks as our units are on loan at the moment.

Mike

 

[opkacz]

In response to Hairball Audio, thank you for the suggestion. That was the issue, because I had reversed the pots. I switched the pots and  went through the calibration process again.  I now have a fully functioning compressor.  This was my first electronics project of this magnitude and I have to say I am actually surprised that this was the only mistake I made.