Hairball Audio: 1176 Stereo Linking PCBs Support Thread

[mhuss]

Just (finally!) finished my dual mnats 1176 with the Hairball red link cards . Both channels seem to work fine in dual mode. When in linked mode, sufficient input on channel 1 causes both channel meters to indicate GR as I would expect. However, the same input on channel 2 causes that channel to show /more/ GR while the channel 1 meter doesn't move.

All the connections and voltages on the red cards look good. However, I noticed that when I put in in dual mode, the input to the link switch (coming from pad 15 on the ch. 1 ratio board) goes flat - the signal stops. This happens even when the wire is disconnected at the red board (loop) end! 

I checked the DPDT switch and wires carefully with an ohmmeter and the switch seems to be working fine, and nothing is shorted to ground.

Any ideas what I should look at next?

 

[joaofar]

Hey guys,

I hope there is still someone out there since this looks like a stalled post, but anyways...

I need your help, I'm stuck.
I built a stereo version of Mnats rev. J boards with Hairball's stereo link (the stereo link was home etched).
Like some here, it works perfectly in dual mode, but when I switch into stereo mode the 2 channels are around 3-5db off (I did ricothetroll's wiring)

I read all the posts I could find about stereo linking 1176 but nothing there has helped me fix it so far.

The stereo link boards were home etched, so the first thing I thought was that there was something wrong with them. I measured the input (loop) on both boards while feeding a sine wave into both channels and they were feeding very different values, something like ~0.3V vs ~1.1V. The value was the same at the XLR inputs, around 0.775V, which I used to calibrate them. The input knobs on both channels were matched for the purpose of this test.

I then connected the XLR inputs directly to the boards (via the loop input) to be able to test them without the rest of the circuitry and there everything appeared to work normally, the summing worked as advertised.
So I'm assuming the stereo link boards are fine.
If this test methodology is wrong would someone suggest a better way for me to test them?

Since the mono channels are working fine, and tracking quite close in dual mode, I really don't know what to do next. The closest thing I found was germoju's post about matching other transistors in the main boards, but it was for a version D which seems to use different ones. Is this something I should investigate? I really don't feel like unsoldering transistors for no reason...

So, any suggestions?



P.S.The fets were matched, and I think they are really close, I'll leave the numbers below:

Device VGS (V) VDS (V) ID (mA)
1 0.00 0.358 0.96
1 -0.25 0.50 0.95
1 -0.50 1.50 0.85
1 -0.75 5.87 0.41
1 -1.00 9.02 0.10
1 -2.00 9.94 0.01
1 -3.00 9.94 0.01
Device VGS (V) VDS (V) ID (mA)
8 0.00 0.37 0.96
8 -0.25 0.49 0.95
8 -0.50 1.45 0.86
8 -0.75 5.87 0.41
8 -1.00 9.04 0.10
8 -2.00 9.94 0.01
8 -3.00 9.94 0.01
Device VGS (V) VDS (V) ID (mA)
6 0.00 0.37 0.96
6 -0.25 0.50 0.95
6 -0.50 1.59 0.84
6 -0.75 6 0.85
6 -1.00 9.08 0.09
6 -2.00 9.94 0.01
6 -3.00 9.94 0.01
Device VGS (V) VDS (V) ID (mA)
12 0.00 0.37 0.96
12 -0.25 0.50 0.95
12 -0.50 1.55 0.85
12 -0.75 6.00 0.40
12 -1.00 9.09 0.09
12 -2.00 9.94 0.01
12 -3.00 9.94 0.01

 

[Mikolaj]

I have built a dual 1176 rev D compressor rotary version. Works perfectly.
Trying the to make the hair ball stereo link to work. Nothing happens on the meters? ( followed hairball instructions)
I read there is an alternative wiring diagram for the rotary version by  Ricothetroll And they say it works but the link is dead. The instructions seem simple enough but I’m stumped.
Is there a list somewhere of voltages or signal paths that I can start trouble shooting or is there something special to do for rotary versions?
Thank you

 

[Echo North]

I have built a dual 1176 rev D compressor rotary version. Works perfectly.
Trying the to make the hair ball stereo link to work. Nothing happens on the meters? ( followed hairball instructions)
I read there is an alternative wiring diagram for the rotary version by  Ricothetroll And they say it works but the link is dead. The instructions seem simple enough but I’m stumped.
Is there a list somewhere of voltages or signal paths that I can start trouble shooting or is there something special to do for rotary versions?
Thank you

Do you have the link wire in the PCBs?  You need to use a resistor lead or something.

Mike

 

[joaofar]

Hey guys,

Still haven't solved this one...  :'(
Any tips on how to troubleshoot why I'm getting a 2/3 dB difference between channels when in link mode?

They both work quite similarly in dual mode when fed the same signal.
When in link mode both channels react to audio even if only one is fed a signal.
I've switched the stereo boards around but the behaviour is the same, the left channel always compresses more than the right no matter what signal I feed where and what knobs I turn, so that leaves me thinking that the summing is working fine and then when each channel reacts to the signal they do it differently?! Even when very close in dual mode?

Any tips/suggestions on where to look are truly appreciated, I'm completely stuck.
Thanks!

Hey guys,

I hope there is still someone out there since this looks like a stalled post, but anyways...

I need your help, I'm stuck.
I built a stereo version of Mnats rev. J boards with Hairball's stereo link (the stereo link was home etched).
Like some here, it works perfectly in dual mode, but when I switch into stereo mode the 2 channels are around 3-5db off (I did ricothetroll's wiring)

I read all the posts I could find about stereo linking 1176 but nothing there has helped me fix it so far.

The stereo link boards were home etched, so the first thing I thought was that there was something wrong with them. I measured the input (loop) on both boards while feeding a sine wave into both channels and they were feeding very different values, something like ~0.3V vs ~1.1V. The value was the same at the XLR inputs, around 0.775V, which I used to calibrate them. The input knobs on both channels were matched for the purpose of this test.

I then connected the XLR inputs directly to the boards (via the loop input) to be able to test them without the rest of the circuitry and there everything appeared to work normally, the summing worked as advertised.
So I'm assuming the stereo link boards are fine.
If this test methodology is wrong would someone suggest a better way for me to test them?

Since the mono channels are working fine, and tracking quite close in dual mode, I really don't know what to do next. The closest thing I found was germoju's post about matching other transistors in the main boards, but it was for a version D which seems to use different ones. Is this something I should investigate? I really don't feel like unsoldering transistors for no reason...

So, any suggestions?



P.S.The fets were matched, and I think they are really close, I'll leave the numbers below:

Device VGS (V) VDS (V) ID (mA)
1 0.00 0.358 0.96
1 -0.25 0.50 0.95
1 -0.50 1.50 0.85
1 -0.75 5.87 0.41
1 -1.00 9.02 0.10
1 -2.00 9.94 0.01
1 -3.00 9.94 0.01
Device VGS (V) VDS (V) ID (mA)
8 0.00 0.37 0.96
8 -0.25 0.49 0.95
8 -0.50 1.45 0.86
8 -0.75 5.87 0.41
8 -1.00 9.04 0.10
8 -2.00 9.94 0.01
8 -3.00 9.94 0.01
Device VGS (V) VDS (V) ID (mA)
6 0.00 0.37 0.96
6 -0.25 0.50 0.95
6 -0.50 1.59 0.84
6 -0.75 6 0.85
6 -1.00 9.08 0.09
6 -2.00 9.94 0.01
6 -3.00 9.94 0.01
Device VGS (V) VDS (V) ID (mA)
12 0.00 0.37 0.96
12 -0.25 0.50 0.95
12 -0.50 1.55 0.85
12 -0.75 6.00 0.40
12 -1.00 9.09 0.09
12 -2.00 9.94 0.01
12 -3.00 9.94 0.01

 

[Echo North]

Hey guys,

Still haven't solved this one...  :'(
Any tips on how to troubleshoot why I'm getting a 2/3 dB difference between channels when in link mode?

They both work quite similarly in dual mode when fed the same signal.
When in link mode both channels react to audio even if only one is fed a signal.
I've switched the stereo boards around but the behaviour is the same, the left channel always compresses more than the right no matter what signal I feed where and what knobs I turn, so that leaves me thinking that the summing is working fine and then when each channel reacts to the signal they do it differently?! Even when very close in dual mode?

Any tips/suggestions on where to look are truly appreciated, I'm completely stuck.
Thanks!

2-3 dB ob the output? That would be your output pot tolerance.

 

[Potato Cakes]

2-3 dB ob the output? That would be your output pot tolerance.

That seems to be working correctly, as Mike suggested. Also, if you're testing this just tone, there will be some difference, but when using program material the stereo channels track very closely to each other. The stereo linking PCB doesn't match the input and output of the units, those still have to be tweaked for each channel. And also there is the tolerance factor as Mike stated. Even quality potentiometers are 20% tolerance. Try testing the stereo linking with a drum mix instead of tone and see how much difference you need between the output controls to get something more evenly matched.

Thanks!

Paul

 

[Reddbo]

Hello,

can anyone tell me how to connect the stereo link board to the +8 pushbutton?
Unfortunately, it is not written in the manual.

Thx 

 

[Echo North]

See below but you also need to cut/alter traces on the meter PCBs and I'm not sure what version of that you have. 

For the connectors you need the datasheet or DMM to figure out what is T R and S.  Super basic stuff.

Mike

 

[Reddbo]

Thx Mike.
I only took the picture from page 6 ( https://groupdiy.com/index.php?topic=35656.msg611260#msg611260 ).  I know wiring of connector.

 

[joaofar]

That seems to be working correctly, as Mike suggested. Also, if you're testing this just tone, there will be some difference, but when using program material the stereo channels track very closely to each other. The stereo linking PCB doesn't match the input and output of the units, those still have to be tweaked for each channel. And also there is the tolerance factor as Mike stated. Even quality potentiometers are 20% tolerance. Try testing the stereo linking with a drum mix instead of tone and see how much difference you need between the output controls to get something more evenly matched.

Thanks!

Paul

Hey guys, thanks for the feedback and suggestions.
Sorry for the late reply, but I don't seem to be getting notifications from this post, and also I left this issue "resting" for the past year since this stereo link was driving me nuts.

Did not know about pot tolerance, in all my noobice, was a bit shocked by that.
I tried a drum mix, and I sort of almost get them ok but it still feels like something is off.
One side will always compress more than the other. Previously when I meant 3-5db was not output, it was GR.
It's a lot and very noticeable.

In dual mono they track to around half a db up to 15db of GR in all ratios which is awesome, I'm really happy with that.
But as soon as that link is activated one channel start to compress a lot more and then of course the outputs get really unmatched. I can try and match them but the compression difference is always there.

So here are some things I noticed when in link mode:

• If I feed a sine to only one side the other one reacts but the 3-5db difference is still there. If only one side is being fed shouldn't the gain reduction be exactly the same on both channel meters?
• If I match them really well in dual mode and then switch to stereo sometimes the compression is canceled on both sides, and then as soon as I tweak one of the inputs the difference becomes huge very fast.
• In stereo, the release pot has a huge influence on the compression, something also along the lines of 3-5db. In fact, the only way I can get them to match the compression level is to tweak the release. But that just makes the release on both channels really different, one is really fast and the other really slow

Would you say this is normal when feeding a sine? Feels weird.

If not, how can go about and troubleshoot this?
My limited understanding of electronics makes following a schematic a bit hard, although I have tried.
I also read the stereo 1176 and the stereo link post again from beginning to end but couldn't find any answers to my issues.
The ones that were close to mine were ricktherolls which was solved by soldering the fets to the board and gemou that had a grounding issue, which I checked on mine, seems fine.

Since my link boards were home etched, how can I go about and be sure they are working properly?
Any suggestions on how to test them? I think that's where I should start.

Appreciate all your help, thank you so much

 

[Echo North]

Hey guys, thanks for the feedback and suggestions.
Sorry for the late reply, but I don't seem to be getting notifications from this post, and also I left this issue "resting" for the past year since this stereo link was driving me nuts.

Did not know about pot tolerance, in all my noobice, was a bit shocked by that.
I tried a drum mix, and I sort of almost get them ok but it still feels like something is off.
One side will always compress more than the other. Previously when I meant 3-5db was not output, it was GR.
It's a lot and very noticeable.

In dual mono they track to around half a db up to 15db of GR in all ratios which is awesome, I'm really happy with that.
But as soon as that link is activated one channel start to compress a lot more and then of course the outputs get really unmatched. I can try and match them but the compression difference is always there.

So here are some things I noticed when in link mode:

• If I feed a sine to only one side the other one reacts but the 3-5db difference is still there. If only one side is being fed shouldn't the gain reduction be exactly the same on both channel meters?
• If I match them really well in dual mode and then switch to stereo sometimes the compression is canceled on both sides, and then as soon as I tweak one of the inputs the difference becomes huge very fast.
• In stereo, the release pot has a huge influence on the compression, something also along the lines of 3-5db. In fact, the only way I can get them to match the compression level is to tweak the release. But that just makes the release on both channels really different, one is really fast and the other really slow

Would you say this is normal when feeding a sine? Feels weird.

If not, how can go about and troubleshoot this?
My limited understanding of electronics makes following a schematic a bit hard, although I have tried.
I also read the stereo 1176 and the stereo link post again from beginning to end but couldn't find any answers to my issues.
The ones that were close to mine were ricktherolls which was solved by soldering the fets to the board and gemou that had a grounding issue, which I checked on mine, seems fine.

Since my link boards were home etched, how can I go about and be sure they are working properly?
Any suggestions on how to test them? I think that's where I should start.

Appreciate all your help, thank you so much

Never test with a pure sine tone.  For whatever reason (phase probably) the link does not work well with it.  Just test with program material or white noise.

 

[Echo North]

Are your FETs fairly matched between units?

Same TPad type?

 

[joaofar]

Hey Mike,

I tried some white noise instead of a sine and it reacts in similar fashion, one side is always compressing 5db more than the other side when the link is on.

In case it matters, I built a dual mnats rev J rotary version in a single enclosure.
The tpad is the input, right? Well, I did match the 10K input pots recently after reading about pot tolerance, so they are very close now. Did not change the behavior almost at all.
I'll try to calibrate it again, don't know if changing the pots messed that up.

I did match the 4 fets as closely as I could, but there could have been mistakes.
Here are the numbers of the selected 4 I got from matching:

Device  VGS (V)  VDS (V)  ID (mA)
1  0.00  0.358  0.96
1  -0.25  0.50  0.95
1  -0.50  1.50  0.85
1  -0.75  5.87  0.41
1  -1.00  9.02  0.10
1  -2.00  9.94  0.01
1  -3.00  9.94  0.01

Device  VGS (V)  VDS (V)  ID (mA)
8  0.00  0.37  0.96
8  -0.25  0.49  0.95
8  -0.50  1.45  0.86
8  -0.75  5.87  0.41
8  -1.00  9.04  0.10
8  -2.00  9.94  0.01
8  -3.00  9.94  0.01

Device  VGS (V)  VDS (V)  ID (mA)
6  0.00  0.37  0.96
6  -0.25  0.50  0.95
6  -0.50  1.59  0.84
6  -0.75  6  0.85
6  -1.00  9.08  0.09
6  -2.00  9.94  0.01
6  -3.00  9.94  0.01

Device  VGS (V)  VDS (V)  ID (mA)
12  0.00  0.37  0.96
12  -0.25  0.50  0.95
12  -0.50  1.55  0.85
12  -0.75  6.00  0.40
12  -1.00  9.09  0.09
12  -2.00  9.94  0.01
12  -3.00  9.94  0.01

 

[Potato Cakes]

Any static noise is going to yield similar test results as a sine wave. Send a drum track through it or some known program material with a decent dynamic range and then set the controls to see how far off they are to match the compression. It will be much closer but there might still be some slight variation in the control settings.

Thanks!

Paul

 

[joaofar]

Thanks for the suggestions Paul.

I re-calibrated both units and while doing that I noticed there was something wrong with my soundcard outputs, they were sending really different levels, which were messing up with stereo. So odd. I changed to another stereo output and got a matched signal arriving at the unit.

Although a bit more minimized, around 2/3 db difference, I still get the same issue where one side is compressing more than the other.

In stereo link mode, when feeding a signal to only one side, shouldn't the compression be exactly the same on both sides? I mean the meters showing the same level of GR. And assuming they are fairly matched in dual mono.

Should also the release pots influence the compression level so much when changing them in stereo mode?

Thanks guys!

 

[joaofar]

Yeah, not getting closer to solving this one.

issue:
in stereo mode one channel is compressing a lot more than the other.
the difference is constant and it's of no avail to change the input to try and match it.
the difference gets larger if the compression is higher, feels like it's on a multiplier.
it doesn't matter what i feed in, sine, white noise, program material, the behavior is always the same.
release or attack changes can change the compression of the other channel in a dramatic way, almost 5 to 6dB.


I re-did the stereo boards on some perfboard with new components and they perform exactly the same as before,
Also switched the channels being fed into the stereo boards and the result is also the same, so I'm assuming the stereo link is ok.


It's hard to troubleshoot this since they are working correctly in dual mono, and are quite close to each other.
I tried the pin 7 join method and it works almost ok, much better than the stereo link boards in my case, the meters shift slightly in opposite directions but are around 1db apart and compress the same amount on both channels.

If the stereo board is also fine, what am I missing?
This is driving me crazy, and it's the last thing to close this build, since I'm a bit OCD can't let this one go.
If anyone with close knowledge of the circuit reads this, please give me a hand troubleshooting.


to anyone who has a dual with link working could you test this in yours?:
In stereo link mode, when feeding a signal to only one side, shouldn't the compression be exactly the same on both sides? I mean the meters showing the same level of GR. And assuming they are fairly matched in dual mono.

Should also the release pots influence the compression level so much when changing them in stereo mode?

Thanks!

 

[joaofar]

Yeah, not getting closer to solving this one.

issue:
in stereo mode one channel is compressing a lot more than the other.
the difference is constant and it's of no avail to change the input to try and match it.
the difference gets larger if the compression is higher, feels like it's on a multiplier.
it doesn't matter what i feed in, sine, white noise, program material, the behavior is always the same.
release or attack changes can change the compression of the other channel in a dramatic way, almost 5 to 6dB.


I re-did the stereo boards on some perfboard with new components and they perform exactly the same as before,
Also switched the channels being fed into the stereo boards and the result is also the same, so I'm assuming the stereo link is ok.


It's hard to troubleshoot this since they are working correctly in dual mono, and are quite close to each other.
I tried the pin 7 join method and it works almost ok, much better than the stereo link boards in my case, the meters shift slightly in opposite directions but are around 1db apart and compress the same amount on both channels.

If the stereo board is also fine, what am I missing?
This is driving me crazy, and it's the last thing to close this build, since I'm a bit OCD can't let this one go.
If anyone with close knowledge of the circuit reads this, please give me a hand troubleshooting.


to anyone who has a dual with link working could you test this in yours?:
In stereo link mode, when feeding a signal to only one side, shouldn't the compression be exactly the same on both sides? I mean the meters showing the same level of GR. And assuming they are fairly matched in dual mono.

Should also the release pots influence the compression level so much when changing them in stereo mode?

Thanks!

Any owners of a stereo 1176 out there that can give me some help weeding out these issues?   

 

[Ricardus]

The blue ceramic capacitors that come with the stereo link module appear to have no markings whatsoever, and they call came in the same bag, so other than with a capacitance tester, is there any way to tell them apart?

 

[Echo North]

The blue ceramic capacitors that come with the stereo link module appear to have no markings whatsoever, and they call came in the same bag, so other than with a capacitance tester, is there any way to tell them apart?

They definitely have marking on them. They are hard for some people to see for some reason, it comes up occasionally. They are on one side, get them under bright light.  You can also try dusting them with a fine powder, sometimes that sticks to the printing.

Capacitance testing small value caps is weird because you probes/terminals will have more capacitance then the cap. However you can still sort them by the elevated value to figure out which cap is which.

Mike