[BUILD] 1176LN Rev D DIY

[Dr. Lessley]

please disregard last post....i figured it out...thanks for all your help mike, comp is working perfectly and sounding amazing!

 

[midwayfair]

Had a question about the input attenuator.

Is there a specific noise improvement by using the 3-gang potentiometer over the original's 2-gang+resistor (looks like maybe the original couldn't silence the input?)

OR

over using e.g. a 1K pot on the secondary as a voltage divider?

I guess I'm mostly just curious about this reasoning behind this design element -- it looks like it might be another thing snagged from the Purple Audio, who appear to have paid (and charged) an absolute fortune for the part when they first started using it. The Hairball price is a bargain compared to that but still ... :O

Also I'm cheap.

 

[Echo North]

Had a question about the input attenuator.

Is there a specific noise improvement by using the 3-gang potentiometer over the original's 2-gang+resistor (looks like maybe the original couldn't silence the input?)

OR

over using e.g. a 1K pot on the secondary as a voltage divider?

I guess I'm mostly just curious about this reasoning behind this design element -- it looks like it might be another thing snagged from the Purple Audio, who appear to have paid (and charged) an absolute fortune for the part when they first started using it. The Hairball price is a bargain compared to that but still ... :O

Also I'm cheap.

No it's just two different ways to achieve the same pot. The three deck pot is a lot easier to get manufactured.

Mike

 

[Bonsaimaster]

Ok I am on my 2nd 1176 build. Having an issue. I will call UNIT A working and UNIT B not working when I go to calibrate in step one I can hear the 1Khz signal but can only get the meter needle to move very slightly.  Since I have two units I have been swapping parts to see what might be the issue.

Swapped boards and both boards work in UNIT A and both do the same thing in UNIT B.
Took the  input transformer and attenuator in UNIT A and put into UNIT B - no change
Replaced the OUTPUT, RELEASE and ATTACK on UNIT B - no change
Swapped POWER BOARD both work in unit A - no change in UNIT B

Can the output transformer be the problem? Or any other suggestions?

Thanks
Daniel

 

[ln76d]

Try unbaalanced. If you are using original output or replica, did you linked properly yellow/orange wires?
You can also measure resistance of input and output windings on both transformers.

 

[Bonsaimaster]

Thanks.  Yes yellow and orange are connected and I get ohm resistance across each winding.

 

[ln76d]

So it's not transformer
If you are using several connectors for wiring pcb check all connections, even with a beeper.

 

[midwayfair]

You could also try audio probing. Alligator clip a cap to the tip of a 1/4" and plug the other end of the wire into an interface or something. Run a test signal or microphone through the input. Listen on headphones or monitors and each audio input and output point in the signal path and see where the problem first occurs. If you have signal up to the power transistor, you're probably good right up to the output transformer.  I'm not totally sure if you can probe at the output of the power transformer if there's a problem with the OT, though. Someone more knowledgeable about transformers will have to answer that.

It does sound like the only thing that HASN'T changed in unit B is the output transformer and the jack. You could, of course, move the output transformer leads to the other board to test that.

 

[Echo North]

Sorry, I haven't followed this too closely. But if you're sure everything is correct, try reflowing any suspect joints. It's amazing how many repairs we do come down to that.

Mike

 

[Bonsaimaster]

I did put another board into this wired box and it had the same problem. Transfer both boards to a working box and they both work. Seems to be in the wiring-transformer. I am going to try to re wire the whole thing tonight and see what happens.

 

[Bonsaimaster]

FIXED! Found a loose resistor connector on the release pot. Anyone having to use a 10k variable resistor to get the 3rd calibration?

 

[exiquio]

Hi guys, I created a new post but a user suggested I post in here to better find a possible solution to my issue. So here goes:

We have just finished the build of the compressor and started doing the calibration for the device. We have successfully set the q bias step but are having issues with the rest of the calibration steps. On the Discrete meter null adjust, we cant seem to zero out both the meter and the DMM. I keep bouncing around .5VDC. I wanted to know if you have some troubleshooting guides for us to check to make sure there was nothing wrong from the circuit build or maybe you can point us to the right direction as to why this is happening. Thank you in advance for your response.

 

[Echo North]

Hi guys, I created a new post but a user suggested I post in here to better find a possible solution to my issue. So here goes:

We have just finished the build of the compressor and started doing the calibration for the device. We have successfully set the q bias step but are having issues with the rest of the calibration steps. On the Discrete meter null adjust, we cant seem to zero out both the meter and the DMM. I keep bouncing around .5VDC. I wanted to know if you have some troubleshooting guides for us to check to make sure there was nothing wrong from the circuit build or maybe you can point us to the right direction as to why this is happening. Thank you in advance for your response.

-Possible the Q12/Q13 are too mismatched.  Did you HFE match them?

-Could try a different pair.  Double check all of the values in that section, and the wiring to it.  Re-flow and odd joints. 

-Set all the trimmers in that calibration step to middle and try again.

Mike

 

[exiquio]

Thank you very much for the quick reply Mike and forgive me since I'm a bit of a Noo-b, is it possible that they are mis-matched even if I'm strictly using parts in the Hairball Audio kit?

 

[Echo North]

Thank you very much for the quick reply Mike and forgive me since I'm a bit of a Noo-b, is it possible that they are mis-matched even if I'm strictly using parts in the Hairball Audio kit?

There is a section in the build guide where it mentions matching those particular FETs for HFE.  You have to do that part from the stack we send you.  Generally any 2 are ok. But not always.

Mike

 

[exiquio]

OK, I'll check and report back asap. Thanks again.

 

[mikey]

I've recently built my hairball 1176 rev D compressor without any major problems but with a lot of fun.

The calibration went alright although the needle and the ouput voltage are dancing a slight bit during calibration. I've read that it could be a wiring issue (antenna). Although, I don't think that the wires are too long...

I would be very grateful if the experienced community here could answer my questions below:

A) when changing the ratios it takes my compressor about 5-6 seconds (after pushing the ratio button) till the gain reduction (and so the sound volume) and the meter go up to about zero. Is this normal behavior? On some youtube videos I've seen changing the ratio works pretty immediately. Not so here...

B) When putting my compressor as an insert on a channel in my DAW I can see some fluctuating/dancing signal (noise) up to -36db on the meter in the DAW! (not on the compressor meter). I don't think I can hear it but is this normal that a ground noise floor appears on the channel when connecting external hardware? Maybe this comes from the dancing needle, antenna behavior?

Thanks a lot for any input!

 

[Echo North]

I've recently built my hairball 1176 rev D compressor without any major problems but with a lot of fun.

The calibration went alright although the needle and the ouput voltage are dancing a slight bit during calibration. I've read that it could be a wiring issue (antenna). Although, I don't think that the wires are too long...

I would be very grateful if the experienced community here could answer my questions below:

A) when changing the ratios it takes my compressor about 5-6 seconds (after pushing the ratio button) till the gain reduction (and so the sound volume) and the meter go up to about zero. Is this normal behavior? On some youtube videos I've seen changing the ratio works pretty immediately. Not so here...

B) When putting my compressor as an insert on a channel in my DAW I can see some fluctuating/dancing signal (noise) up to -36db on the meter in the DAW! (not on the compressor meter). I don't think I can hear it but is this normal that a ground noise floor appears on the channel when connecting external hardware? Maybe this comes from the dancing needle, antenna behavior?

Thanks a lot for any input!

A) Depends where your release knob is.  If it's on the fastest setting it should be fairly quick, but it still takes time...it's not instantaneous.

B) Hmmmm hard to say.  You should not get noise that high, but there are just so many variables to pin point it over the forum.  You're needle should not be twitching. Maybe look for loose wire connections and reflow wire solder connections.  Make sure BLK on the ratio PCB has a clear path to ground on the main PCB through the GR on/off switch.

Mike

 

[dgold]

I hope this is the correct location for this issue:
I have completed my build of the revD 1176 and have completed the first 2 calibration steps without difficulty but am unable to get the meter to work correctly.  In fairness, I was unable to match the HFE for the transitors so it may be related to that.  When setting up to calibrate, I am unable to get the meter to zero using the zero adjust pot.  When running the compressor, the meter does not deflect in either +4, or +8 settings with hot signal coming in input.  Thanks for any advice.
Dave

 

[Echo North]

I hope this is the correct location for this issue:
I have completed my build of the revD 1176 and have completed the first 2 calibration steps without difficulty but am unable to get the meter to work correctly.  In fairness, I was unable to match the HFE for the transitors so it may be related to that.  When setting up to calibrate, I am unable to get the meter to zero using the zero adjust pot.  When running the compressor, the meter does not deflect in either +4, or +8 settings with hot signal coming in input.  Thanks for any advice.
Dave

Is the needle moving at all?

Mike