Stereo 1176 support - Mnats/Hairball

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dandeurloo

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Hey Guys as a proud owner of a few stuffed Mnats rev. d's and a Hairball kit and a few cases (I know, I know) I am close to wrapping up my 1176's.  I read through the massive Mnats Rev. D help thread and notice some of that info is old and much of it is about strictly older revisions of Mnat boards which have now been updates.  Also not all of it applies to the specifics of the Stereo 1176's and it seems to be starting to get confusing meshing the wiring of the stereo 1176 with the mono units.  So, I was hoping to start a new thread dedicated to the Stereo versions. 

The other thread should still keep alive and well because it has great info in it and specifics of wiring up Hairballs kits in his excellent cases.  Hopefully this will help keep info more organized and clear.

I will do the best I can to keep this first thread up to date with the current and accurate help notes in case it becomes an 85 page help thread guys can find info a little quicker!

Ok, the things that could be helpful from any of you would be wiring diagrams and photos of how you have had successful layouts of the boards in the chassis. 

Thanks guys!


Helpful Links:
Rotary Switch Wiring - (http://mnats.net/1176-wiring-rotary.html)
Slam Mode Switch Wiring - (http://mnats.net/1176_slam_mode_rotary.html)
Calibration Videos - (http://mnats.net/1176_revision_d.html#videos)
Stereo Link Boards Wiring - (http://hairballaudio.com/guides/Stereo_Link_Wiring_Guide.pdf)
Stereo Link Boards Wiring - (http://www.wuala.com/ricothetroll/public/Stereo-Link_wiring.gif)
Stereo Link Boards Help thread - (http://www.groupdiy.com/index.php?topic=35656.0)
BOM for Mnats PSU - (http://mnats.net/psu.html)


R12 for Rev D ( http://www.groupdiy.com/index.php?topic=44909.0)
 

dashbad

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I'm also finding this link from the mnats site useful: http://mnats.net/1176-wiring-rotary.html
 

dandeurloo

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Dash can you confirm this once you get a little further.  I'm hopefully gonna get to work on mine a little this weekend.
 

dashbad

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I have a couple of questions about the Master bypass/Comp control

How should this be connected? Does it not duplicate the function of the GR OFF position of the meter switch? Is it just a case of wiring pad 22 on the main PCB through the switch so that it connects to ground in the off position and connects to Pad 22 on the meter switch board when on?



 

dandeurloo

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Dash The master Bypass requires another true bypass board.  Marc has some that I think will work and so does Igor.
 

dandeurloo

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Questions about wiring up the Stereo Link boards.

1. Should the ground go to the main boards or back to star ground for the least amount of noise?
2. Do I wire a lead from both boards ("link" pads) to the link switch?  Or is it just one wire from board #1 to the link switch?
3. On the ratio boards are the "OUT PUT" sections to be tied together or left empty.  The diagram from this link is slightly confusing. http://www.wuala.com/ricothetroll/public/Stereo-Link_wiring.gif
 

KasperNyhus

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Hi Guys

I'm also confused about this stereo link board wiring... Hooked it up as shown in the drawings but I never got it to work properly...

When Dual mode is flipped on channel 1 fully attenuates the signal and comes back again after some seconds. Also the input has to be much higher in dual mode to get the same amount of compression compared to mono mode. And finally the two channels doesn't affect each other - thats a bad stereo link then...  ;D

If there is someone who has made this work I would be very happy to see the wiring!!

I will follow this thread...
 

dashbad

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Dan - I would take the ground from the link boards back to the Star Ground. I also think you should wire both boards to a DPDT switch.

I've left the 'output' sections on the ratio boards empty.

I've finished mine and it seems to be working fairly nicely on dual mono mode. I have one issue when I use it in Slam mode. In this mode the meter works fine on the +4 setting, but when I move it to show GR the meter goes hard right. It responds to the input - so it shows gain reduction, it just seems to go hard right whenever it returns to zero. The meter shows GR correctly in all other ratio settings. Any ideas? Is this expected behavior.....? I've got a feeling it might be....

Also - not quite sure how to verify that link mode is working correctly. When I engage it only one channel seems to be working and it the amount it is compressing reduces significantly. The GR meter on the other channel is unresponsive.

Also, I find moving the release affects the meter GR display by 3-4db. I've read somewhere this might be due to the diodes used in the circuit. Does anyone have any more info?


 

dandeurloo

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hmm.  interesting.  At least you are making some good forward progress!  I am not sure if it would matter if it is a dpdt or a spdt switch?  I think either way they do the same thing in this case.  Am I wrong there?

I'm no help as of yet on the Meter question you are still a head of me.
 

dashbad

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Am pretty sure you want DPDT rather than SPDT. You don't want to be summing the sidechains at the switch - you should leave that to the Link boards so the sidechain should be isolated until it gets there.

Think of it as the wiring image you link in the first post only showing one side of the switch. You need double throw as you either want the sidechain connected directly to the ratio board OR to the link board. The bottom line is that it needs to be connected to something

Thats the way I see it anyway. By no means an expert.....
 

dandeurloo

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Ok, that makes sense.  I knew they would get summed together but I guess that is what the boards are for!

Also to confirm something.  The .022uf and 470 resister for the attack pot and the 270k resistor for the release pot are all on the ratio boards for the rotary versions correct.  So no need to do those on the pots.

I'm slowly picking through this. 
 

Echo North

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dandeurloo said:
Questions about wiring up the Stereo Link boards.

1. Should the ground go to the main boards or back to star ground for the least amount of noise?
2. Do I wire a lead from both boards ("link" pads) to the link switch?  Or is it just one wire from board #1 to the link switch?
3. On the ratio boards are the "OUT PUT" sections to be tied together or left empty.  The diagram from this link is slightly confusing. http://www.wuala.com/ricothetroll/public/Stereo-Link_wiring.gif

1.  See here http://www.groupdiy.com/index.php?topic=35656.msg481187#msg481187 looks like the start ground is a better option.
2. Both to the switch (DPDT) if I understand you correctly.
3. Output just connects to 15 16 17.  I don't have a ratio rotary board here but I think you can ignore those pads.

Good luck!

Mike

edit:  Now I see dashbad answered this already ;)
 

Echo North

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KasperNyhus said:
Hi Guys

I'm also confused about this stereo link board wiring... Hooked it up as shown in the drawings but I never got it to work properly...

When Dual mode is flipped on channel 1 fully attenuates the signal and comes back again after some seconds. Also the input has to be much higher in dual mode to get the same amount of compression compared to mono mode. And finally the two channels doesn't affect each other - thats a bad stereo link then...  ;D

If there is someone who has made this work I would be very happy to see the wiring!!

I will follow this thread...

Check the stereo link thread.  There is some discussion about the stereo link hook up in a rotary build.

Mike
 

Echo North

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dashbad said:
Also - not quite sure how to verify that link mode is working correctly. When I engage it only one channel seems to be working and it the amount it is compressing reduces significantly. The GR meter on the other channel is unresponsive.
Remember for this stereo link method, all settings should be identical.  If you are feeding a signal into each channel that are relatively the same, you can tweek the output and input to adjust for variances in components between units.  Once they are compressing identical, if one side gets an additional tone burst, both meters should react the same.

Mike
 

dashbad

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Thanks Mike,

I'm using matched FETs from yourself. Can you confirm - are all 4 FETs matched so I can use any of them in either unit in either position or do I need make sure 1 pair is used in one channel and the other pair in the other channel?

If the latter, what effect would this have on the unit?

I've also added a question to the stereo link support thread as Ive narrowed down my issue there.

 

Echo North

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I would keep the pair together.  The FETS in one pair are matched within 10% (usually 1-3%) along the full curve.  The pairs themselves all fit within an overall curve.  It probably wouldn't matter too much if you mixed them all up but it may make your meter somewhat off.

Even if two pairs are at opposite ends of the acceptable range, they should be close enough to keep you within 1db of stereo operation down to 10 db of gain.  You may need to adjust the in/out to get the channels matched.

Mike
 

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