GSSL HELP THREAD!!!

[tzman]

Thanks tzman!

The only thing i dont understand is how to wire the bypass switch with these mods, I'd like to use a standard on/off pushbutton as a bypass switch instead of the lorlin rotary one i currently have installed..

No problem!

That's not really different from not using the mods actually...
You could choose to use a DPDT toggle switch. You could then choose to use the original bypass circuitry or choose to use the bypass circuit from the SSC board (which I prefer).
If you would like to use a pushbutton, you would have to use some sort of latching pushbutton, or use a non latching pushbutton which operates a DPDT relay. Only thing then is that you would probably have to use separate power supply for your relay.

Don't skip this: http://www.groupdiy.com/index.php?topic=34219.0
And this: http://www.groupdiy.com/index.php?topic=28443.0

Good luck and feel free to ask!

 

[ptron]

hehe now that i check like that youtube video from keif, my left channel isnt compressing at all while on turbo :/  not sure where on my wiring went wrong.. or if this comes from other problem? ..
weird..
the standard ssl behaviour is normal
any help or ideas will be greatly apreciated

12 and -12 v seem to be ok in the connector on the turbo board.. hrmm

thanks !

EDIT: ... fiddling with that header i think the problem was on the 0v not getting there or something.. now its working (maybe had solder bridge between somewhere and the clips broke it?)
dunno.. it works now tho

 

[AudioguyII]

Hi,


Thx to everyone for the great info,

does this look right? 
Keeping it permanent SSC.

L + R PADS are bridged on each SSC board. (MEANING THE WIRE CONNECTS TO BOTH L AND R)

Can I just remove the old bypass rotary switch?

Any ideas why make up gain is always on?

thx so much

 

[kante1603]

Any ideas why make up gain is always on?

Hi,

have you done the bypass-wiring correctly?
See att. file!

Best,

Udo.

 

[AudioguyII]

thx so much Udo,

before I installed the SSC boards.... bypass was working correctly.
In this diagram, are they referring to the "in/ret SW" on the SSC boards?

thx again!!!!!

 

[audiophreak]

Hi,


Thx to everyone for the great info,

does this look right? 
Keeping it permanent SSC.

L + R PADS are bridged on each SSC board. (MEANING THE WIRE CONNECTS TO BOTH L AND R)

Can I just remove the old bypass rotary switch?

Any ideas why make up gain is always on?

thx so much

  Could someone confirm this Please  ,  I have a 1U GSSL working, and a Turbo board and two SSC boards all populated , would like to hook it up as permanent Turbo, and permanent SSC ( unless SSC selector switch is in the " Off" possition )

  Thanks as all ways 

 

[wahfreak]

Hi all,
I just finished assembling my GSSL. No, SSC, turbo, thrust, not even bypass, just a plain ol' GSSL.  Just an expat VU driver board for the meter. I wanted to make sure it worked first before adding additional troubleshooting issues.

It passes clean audio but does not compress at all. Make up gain does work.

Star grounding to chassis for the IEC, 0V at the power supply, and for the XLR input and outputs.

I have voltages for you to take a look at to see if you can pin point the problem.

Rails measure 14.84VDC and -14.97VDC


TL074
1- (.197)
2- 0
3- 0
4- (12.07)
5- 0
6- (.001)
7- (.004)
8- 0
9- 0
10- 0
11- (-11.93)
12- 0
13- 0
14- (.380)


TL072
1- (.128)
2- 0
3- 0
4- (-11.93)
5- 0
6- (.003)
7- (.898)
8- (12.08)

Any idea where the issue could be??

Thanks for looking.

 

[Bob1991]

Just in case - have you mounted a 47k resistor on the threshold pot?

I hadn't, so actually my sidechain control signal was too low in comparison with the threshold DC voltage > so this prevented the GSSL from compressing.

 

[wahfreak]

Just in case - have you mounted a 47k resistor on the threshold pot?

I hadn't, so actually my sidechain control signal was too low in comparison with the threshold DC voltage > so this prevented the GSSL from compressing.

Thanks, Yes the 47k is installed.

 

[jordan s]

Well, for my unit, I just removed to CRC board and it all works fine, no hum. Closed it up, oh well.
I wanted to note that for me, a 22k resistor on the threshold pot was a better solution. I found that with the 47k resistor, I really had to crank it. With 22k, when I have threshold set at 0 and I'm sending a few db over -18db FS, it's compressing a few db. Of course it depends on the settings but this more or less feels right to me. Now I have a really good range from subtle to total annihilation.

 

[Bob1991]

I finally built my GSSL in it's metal case, but I have one problem left, some phase related issues.

I'm using XLR to mono TRS jack cables for my inputs and outputs (my audio interface only has jacks), so the cold (or the hot?) of the XLR is shared with the ground at the TRS jack side of the cable.

This results in a compressor only compressing stereo panned audio-information. Mono (center) panned audio-information isn't compressed (inverse phase problem).
So I have to manually invert the phase of one channel at the input (so the compressor is compressing as it should do), and then invert the phase of one output again. Then everything is alright, but this is not a suitable way of workaround when the GSSL is outside my studio..

So it is making me a bit confused, does someone know how to wire those XLR's when using it with XLR-to-jack cables?

Last question: Can I mount/ground the main pcb to the chassisground using metal pcb-stands? Or should the pcb be isolated from the chassis?

 

[MikeClev]

Bob, you have to be careful when wiring those inputs and outputs on the standard GSSL because the + and - are very easy to get mixed up.

Input is on 5 pins:

O + Left.   Pin 2 on left XLR. Goes to left TRS jack tip.
O - Left.   Pin 3 on left XLR. Goes to left TRS jack ring.
O Ground.   Pin 1 on both XLRs. Goes to both TRS jack sleeves.
O - Right.   Pin 3 on right XLR. Goes to right TRS jack ring.
O + Right.   Pin 2 on right XLR. Goes to right TRS jack tip.

Output is also on 5 pins but + and - swapped, and also right and left swapped:

O - Right.  Pin 3 on right XLR. Goes to right TRS jack ring.
O + Right.   Pin 2 on right XLR. Goes to right TRS jack tip.
O Ground.   Pin 1 on both XLRs (should go from XLR to star ground, not to here)
O + Left.   Pin 2 on left XLR. Goes to left TRS jack tip.
O - Left.   Pin 3 on left XLR. Goes to left TRS jack ring.

As you can see, with + and - swapping, and right and left swapping, its very easy to get one of the polarities mixed up. I did exactly that on my first GSSL and had the exact problem you described.

Another bit of advice is to not use a cable that shorts the output cold connection to ground, as this means that the opamp will be dumping lots of current which may cause distortion in the output of the other opamp on the hot pin. On my GSSL I put in two pairs of output jacks, one wired for balanced and one wired for unbalanced connection with the cold/- output not connected to anything.

I hope that helps!

-Mike

 

[ilfungo]

excuse me a question
my GSSL SSC +2 + turbo seems to work perfectly
TL and TM when adjusting the first SSC will also change the other channel ...
Is this normal?
thanks

 

[Bob1991]

Thank you very much MikeClev! That's clear to me. I have quite some wires mixed up  I'm gonna fix it very soon.

Could it be that the phase problems are a also result of a mono jack cable (which is indeed shorting 2 pins together)? My cables only have a tip and sleeve, so, my fault, it's a "TS" cable then. It seems the opamps are indeed dumping lots of current, they're quite warm. So maybe i have to spend another €20 on 4 new, balanced cables

Or, does cutting the cold-pin connection on the XLR the job too, without heating the opamps? (so then it's an unbalanced GSSL)

 

[MikeClev]

The mono jack shouldn't cause the phase problems...

Yes, cutting the cold connection on the XLR will stop the cold/- opamp dumping all that current too. If you mean cut it on the socket on the GSSL, just remember it will cause you problems if you ever try to use your GSSL output with balanced XLR gear in future. I would recommend making up a special cable with cold/pin 3 not connected, and label the cable so you know what you modified in future. Or fit two jack sockets on the GSSL connected unbalanced.

 

[MikeClev]

excuse me a question
my GSSL SSC +2 + turbo seems to work perfectly
TL and TM when adjusting the first SSC will also change the other channel ...
Is this normal?
thanks

I'm not an expert on the SSC boards, but I think that changing the SSC setting on the left SSC board will affect the compression on both the left and right channels. They aren't compressed completely independently, the Turbo board means that left and right signals are rectified and detected separately before the sidechain signals are summed. Audio present on the left channel will affect compression on the right channel and vice versa. Compression is applied identically to both left and right, the SSC just affects what audio reaches the sidechain signal going into the sidechain vca.

However, if you put silence through the left channel and music through the right channel, changing the left SSC controls should not affect the compression on the right channel, and vice versa, so check that. If that happens, you must have made a wiring error.

 

[ilfungo]

Thanks Mike
Last question... I hope ???

However, if you put silence through the left channel and music through the right channel, changing the left SSC controls should not affect the compression on the right channel, and vice versa, so check that. If that happens, you must have made a wiring error.

I want the turbo switchable
I noticed that:
turbo OFF
everything works fine L-R are independent
Turbo ON
signal - L no compression
signal - R ok compression
signal in both - both compress
Is this normal?
I connected this way:


SSC L :
L-R Briging to first removed 47k
Ret to the other side of 47K

SSC L :
L-R Briging to second removed 47k
Ret to central pin of SPDT switch  ( Turbo ON/OFF)

SPDT
up to Turbo Board
down to to the other side of 47K

IT is correct for make turbo Switchable?
Thanks

 

[ilfungo]

???

 

[wahfreak]

Well, I got mine running this week. All the controls work and in compresses but my right side is 6db louder than my left side.

The voltages at each of the input 5534's and the output 5532's are nearly identical.

Near idential voltages for the left and right 5534's in the VCA circuit.

I've rechecked the resistors around the VCA's as well as around the input and output areas. The 15K resistors feeding the VCAs are good.

I've check the wiring 5 times at the inout and output XLR headers and those are good.

I've scoured for bad solders joints with a magnifying glass and checked for broken traces.

The only place I could see an issue is a ground pad in the output section. There's a 100n cap that goes to pin 8 of a 5532 (I think it's the left output. It the closest 5532 to the edge of the board on the bottom left hand side.) The other end of the cap goes to ground. I looks like the ground pad might have lifted but I tried a direct connection to ground and it made no differnce which is why I think it's ok.

I read in a older post about checking the voltages at the XLR pins and I get 0V at pins 2 and 3 against pin 1 (ground) with a 1k signal running through it.

I'm using THAT 2181 VCAs

I'm also running unbalanced cables from my interface to balanced on the GSSL. I've tried swapping cables but that didn't work either

I'm using star grounding. The input grounds are wired together and sent to ground and each output ground is wired together and sent to ground.

I'm running out of options to try. Any guesses as what it might be???

 

[ilfungo]

I solved it!
I discovered that there was a fails track on the Turbo Board ...
Thanks  MikeClev and the entire forum for  patience and support ...
GSSL + Turbo+ 2 SSC sound GREAT!!!