Hairball Audio: 1176 Stereo Linking PCBs Support Thread

Hi guys

I've build myself a stereo 1176 with mnats rev.J pcb and hairball stereo link.
I just can't figure out how to wire them properly?
The way I've done it now, the "dual mono" mode works fine but when I switch on the "stereo" mode one channel sort of sucks the audio and it takes a while before it stops fully attenuating the signal.

Has anybody experienced this behavior?

Also I would really like if one of you guys could point out the right wiring for me.

Thanks,
Kasper

Thanks Randyman,
That pic cleared the fog in my brain. A few more questions:
-Anyone see a problem with having the link toggle switch on the back panel(wire length)?
-Since the original wire between ratio pad 15 and the pot are shielded, should I be shielding the entire set up?

Cheers

Hi,

I'm building a Dual 1176 Gyraf style with a Purusha case (the one with the rotaries). I'm still in the planning fase (waiting for some parts to arrive to finish populating the PCBs) and want to stereo link the two PCBs in a decent fashion. I also want to power the boards with a decent PSU - not using the on board PSU section. All that is easy enough with ready made PCBs available and all but it's no fun to run wires to and from two small PCBs - so I took it a step further; I threw together the schematics of mnats PSU and 2 of your Stereo Link modules, and replaced the big electrolytics of the PSU with the CRC filter of the GSSL - don't know if that will do anything for the unit but it surely won't hurt. I even managed to lay everything out on a single sided board of decent dimensions.

Question is: are you ok with me throwing that out on the public domain? Of course I also wouldn't mind at all if the design would end up in your shop one way or another. I've made everything in Eagle Light, but I can export to pictures too of course.

Well the link design belongs to purple audio.

Honestly, if you mean posting self etch files of your design I think that would cool and I don't think anyone would take issue with it.  It's DIY! 

Mike

OK, here it comes:








Eagle files can be downloaded as well: http://www.virtualogic.nl/diy/1176_crc_link.sch and http://www.virtualogic.nl/diy/1176_crc_link.brd

Hi,
I have two G1176 in an enclosure in order to have a dual/stereo compressor. Each compressor works well apart and are closely matched (I measured Vin/Vout on each unit in order to have both transfer curve and they are matched at about 0.2V). I have Hairball's stereo link PCBs and Hairball's HB8037 meters. I wired the stereo link PCBs as showed in my previous post and can be found page 2 of this thread (Mathflan said that he used my wiring successfully).

My problem is when I switch it to be stereo, I have a the 2nd unit that has a (measured) gain reduction of about 2dB more than the first unit. My test procedure is : in dual mode, both channels are fed with the same signal (ch1 from the L output of my soundcard and ch2 from the right one), I scoped both signals at test point 2 - right after the input gain pot - to make sure both compressors are fed with the same signal, I then set the out pot in bypass mode to have unity gain in both units. Then I switch both units to GR and measure both outputs, and see that both gain reduction is the same. When I switch the link switch to link mode, I measure a 2dB difference between ch1 and ch2, that is to say there is a 2dB difference in gain reduction. Meters also display a 2dB difference between the two channels.

I double checked every resistor on both stereo link PCBs, every voltages (on opamps), I only noticed a difference of about 1V between the two +30V rails (respectively measured 29V and 30V). That difference also appears on the main boards (each stereo link PCB is supplied by its corresponding main boards 30V test point). Stereo link PCB's grounds are taken from the star grounding connected to the enclosure, bear the power transformer.

When I scope the signal that comes from each stereo link PCB ("link" test point), they have the same amplitude.

Any help would be appreciated ! Thanx in advance.

Best regards.

Eric

Hey guys, quick check to see if anyone else has gotten this. When I switch the stereo link on my units, the audio level gets really low and sounds high passes. I assume I messed up the wiring somewhere, anyone had this happen and know maybe what exactly I did? I gotta pull them out of the rack and tweak this.

Hi !
i'm building a stereo 1176 with mants rev D PCB ,
and i was wondering if it's better to use the available PSU based on LM317 and 337,
or use the onboard PSU ?
i have the parts for 2 onboard PSU so cost is not a problem,
just looking for the best solution regarding noise etc...
regards,
Francois

I have an issue with one of my channels in a 2-1176.

For some reason when I activate stereo link the input buffer of the left stereo link pcb fails to buffer the signal.

Referencing the schematic the audio signal is present at the input of the first opamp - A201a pin 3 but I get 0V at pin 2 and pin 1. I've disconnected this PCB from the other link PCB and get the same results.

This led me to believe that there was something wrong with the link PCB components and wiring. I've checked all capacitors and swapped out the opamps but get the same behavior. Measuring DC voltages I get 15V (above signal/chassis ground) at the input (pin 3) but again, 0V at pin 1 and 2.

The other channel's link works fine.

Can anyone help?

Maybe a dumb question, but you have the shorting wire installed on both board correct?  They go on the line by the PCB info.

Mike

Yes, this is in place.

Edit: I took a closer look at the board and it appears that one of the legs of one of the Caps had detached from the bottom of the board taking the solder pad with it. i tried to patch this break to the nearest component with a small piece of wire but it hasn't changed anything. Perhaps it has created a short to the ground plane? I think I might need a new PCB so have ordered one to try

Dash did you figure it out?  I'm having a few issues as well.  I am trying to wire it this way but it doesn't seem to work.

http://www.wuala.com/ricothetroll/public/Stereo-Link_wiring.gif

Can you confirm this wiring to work?

Hi All,

If you have any issues with wiring you can reference the Purple Audio MC77 schematic.  The stereo link circuit is from the MC77:

http://www.purpleaudio.com/product/mc77more.html
(bottom of page).

One other thing to clarify is that this circuit is not the same as the tradition link circuit sold as a separate box by UA.  That has a different functionality (this one is better IMO).  I believe with the UA one unit controls both sets of controls.

This circuit simply sums the audio from both side chains.  That way both compressors are seeing the same peak levels in the side chain.  All the controls should be set the same on both units.  Because the pots can have 10-20% tolerances and slight differences in FETs and biasing, you will need to trim the input and output on one unit to get them perfect.

Thanks!

Mike

Yes.

Got my first unit hooked up with this implementation. It seems to work fairly well, but it doesn't connect the DC control voltage at all, so getting the release and attack times exactly perfect on both units is....interesting! It does take a bit of fiddling to get them to dance together. But it works!

Thanks Mike!

abechap024 said:

Yes.

Got my first unit hooked up with this implementation. It seems to work fairly well, but it doesn't connect the DC control voltage at all, so getting the release and attack times exactly perfect on both units is....interesting! It does take a bit of fiddling to get them to dance together. But it works!

Thanks Mike!

Click to expand...

But remember when you connect the control voltages like UA link, you double the attack and release times.  So with that system it's impossible to get fast attack or release times in stereo mode.

Great work!

Mike

Sorry for the stupid question
for 2 x 1176 in the same box, I have to use one or two stereo link PCBs?
Thanks

two:  one for each 1176

sorry
I am building 2 x 1176 rev D in the same box.
I would like to add 2 links PCBs, but just do not understand .....
Looking at this diagram:
To - In the second of the unit?
To - Out of the second unit?
Is there anyone who did it and can help
thanks

ilfungo said:

sorry
I am building 2 x 1176 rev D in the same box.
I would like to add 2 links PCBs, but just do not understand .....
Looking at this diagram:
To - In the second of the unit?
To - Out of the second unit?
Is there anyone who did it and can help
thanks

Click to expand...

At the risk of sounding not very empathetic: it seems confusing at first, but really its not. Just sit down with the picture and wire it up. Step by step. Once you do it its not that hard. Good Luck!

thanks abechap024
was just trying not to make mistakes....