[BUILD] 1176LN Rev D DIY

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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.)
 
RuudNL said:
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
 
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!
 
Hairball Audio said:
babaorum said:
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 .
 
babaorum said:
Hairball Audio said:
babaorum said:
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
 
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.
 
useme2305 said:
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!
 
Hairball Audio said:
babaorum said:
Stay always to 0.00  :eek:

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.
tulipe_transistors.jpg


 
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 ...
 
babaorum said:
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"?
 
Hairball Audio said:
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
 
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!
 
opkacz said:
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
 
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.

Hairball Audio said:
RuudNL said:
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
 
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.
 

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