GSSL HELP THREAD!!!

[rrs]

Ok solved the release issue in first position. 180r instead of 180k :/

But not that simple for the 1:2 ratio issue. I'm guessing maybe another resistor but where ?

Everything close to position one on the ratio switch looks fine.


Also checked rotary switches are locks off from first position.

 

[cray]

Hello .
Just wondering if  IC TL074BCN will works instead a TL074CP.

input max on "CP" series  is 10mv ,  and "BCN" series is 3mv.
there could be some more differences..


I have 5 units here . would like to use them on some gssl projects.

Could i use them?
Thank you

 

[john12ax7]

Do you mean input offset voltage? If so, then less is actually better. It will work fine.

 

[Gustav]

Ok solved the release issue in first position. 180r instead of 180k :/

But not that simple for the 1:2 ratio issue. I'm guessing maybe another resistor but where ?

If you can't read the schematic, trace it from the switch pin and out. The area for a specific setting problem there is very limited...

Gustav

 

[cray]

Do you mean input offset voltage? If so, then less is actually better. It will work fine.

Yes I mean :    VIOmax  AT 25°C

"C" series is : 10mv    and "BC" series is 3 mv

Thank you!

 

[critterkllr]

Hey guys, I have a GSSL that is extremely distorted. Almost to the point of sounding like a bit crusher. The distortion occurs regardless of bypass state. I've spent hours reading through similar issues, but none of them have posted resolutions (if one was ever found).

I'm using the GSSL Rev 7 board with Serpent Audio's Quad VCAs. I couldn't find any info on any modifications to use the Quad VCA, so the components are the same as labeled on the PCB.

The DC voltages read fine on all of the chips except the 5534s. +V on both of these opamps reads +13.3V instead of +15V. I am also only getting -3V on pin 5 of my THAT2181A.

+/-15V tests fine on the PCB at the jumpers going to the VCAs.

I am connecting this to an unbalanced insert on my console, but have connected a balanced Neve compressor after it to make sure the output connects to a transformer balanced out. The input is connected to the insert of my console using a Y cable.

I am using an SPDT toggle switch for bypass. I'm following the wiring posted by pcbgrinder in the latest "new" GSSL assembly guide.

The input and output connections don't have any labeling on the rev 7 PCB. I found a picture of a rev 9 that showed the order of the connections. I have it connected as " + - gnd - + " to the XLRs.

Is there anything I'm overlooking? Anybody find a solution to their problem that was similar to mine?

 

[critterkllr]

i am using serpent audio`s VCA`s for this builds. should i adapt them same as i did with igor`s?
with igor`s VCA`s, i had 2.5k instead of 15k just under the "output" letters on the board also 220pf instead of the 100pf there.
i also used 182k instead of the 1M (% on new board) and a jumper wire instead of the 27k* between regulators and vca`s
i wonder if this is ok with the new VCA boards or i got to do something different?

2K5 feedback resistor is correct if 4 VCAs are fitted per module. I'd increase the 220pF across this feedback resistors to 330pF. Jumper instead of the 27K voltage to current converters (these 4*20K in paralleled VCAs are on the module) is correct as well. The 182K (probably 180K for 4*2181As, 56K for 4*2181Bs or 33K for 4*2181Cs) instead of 1M depends on type of THAT2181 used on VCA modules.

Just found this response from Harpo. Will give this a shot and see if it helps my issue

EDIT: All values changed to the recommended values above, but there is no change. Still tons of distortion and a big level increase.

I clipped the pin 3 from the output XLRs and connected it straight to the console. Didn't help.

Plugging it from my console to the Neve compressor to the GSSL back to the console got rid of the distortion. But only when the right channel on the Neve isn't bypassed. I'm also getting about 6db less on the left side. i swapped the 15K resistors in the output for 2.5k, changed the caps to 330pf as well as clipped pin 3 from the output XLRs. Not sure where I'm going wrong here.

 

[Gustav]

Hey guys, I have a GSSL that is extremely distorted. Almost to the point of sounding like a bit crusher. The distortion occurs regardless of bypass state. I've spent hours reading through similar issues, but none of them have posted resolutions (if one was ever found).

I'm using the GSSL Rev 7 board with Serpent Audio's Quad VCAs. I couldn't find any info on any modifications to use the Quad VCA, so the components are the same as labeled on the PCB.

The DC voltages read fine on all of the chips except the 5534s. +V on both of these opamps reads +13.3V instead of +15V. I am also only getting -3V on pin 5 of my THAT2181A.

+/-15V tests fine on the PCB at the jumpers going to the VCAs.

I am connecting this to an unbalanced insert on my console, but have connected a balanced Neve compressor after it to make sure the output connects to a transformer balanced out. The input is connected to the insert of my console using a Y cable.

I am using an SPDT toggle switch for bypass. I'm following the wiring posted by pcbgrinder in the latest "new" GSSL assembly guide.

The input and output connections don't have any labeling on the rev 7 PCB. I found a picture of a rev 9 that showed the order of the connections. I have it connected as " + - gnd - + " to the XLRs.

Is there anything I'm overlooking? Anybody find a solution to their problem that was similar to mine?

You have introduced a few variables I would eliminate before attempting to trouble shoot it on my bench, but you seem to have gotten off to a good start investigating the stacked VCA.

I am also curious about your voltage reading. The +15V is one supply net, so getting lower voltage on the 5534 suggests you have some basic problem, but I am puzzled why the problem is localised rather than global.

6dB difference also suggest a basic problem.

Do you have a few pictures of your soldering work?

Gustav

 

[joelb]

Thank you very much Bowie, apologies - I didn't realise anyone had replied. My compressor is now fully functioning and sounding sweet thanks to your input sir.

The only issue I have now is that the ratio works backwards still (ie 1:2 = 1:10 and vice verse) but I can live with that, unless anyone else has had, and remedied, the same issue.

Thanks again!

Joel

The first couple sound like you just have your wires crossed up.  Should be an easy fix on those and it might end up correcting some of the other things.
The trace issue sounds like you may have scratched into a wrong or neighboring trace.  Can you go in underneath the board and solder to the original hole?  There's a couple other things you can do but w/o a GSSL board I'm hesitant to say anything specific as I don't know if it will work on your board.

(Edited to avoid confusion based on info below.)

 

[critterkllr]

I am also curious about your voltage reading. The +15V is one supply net, so getting lower voltage on the 5534 suggests you have some basic problem, but I am puzzled why the problem is localised rather than global.

6dB difference also suggest a basic problem.

Do you have a few pictures of your soldering work?

Gustav

I was measuring the wrong pin on the 5534s. I was measuring pin 8 instead of 7. Pin 7 measures good.

I have a box of Jensen 1:1 10k input transformers laying around. I decided to hook two of them up and there is no longer a difference in levels between the channels. Maybe my console just didn't play nice with the balanced inputs?

there is less gain overall in the unit. But perhaps that it because of the unbalanced output? Regardless, I can keep the recovery at noon to have unity when the compressor is in use.

Also, I have the output wiring phase reversed. It's hard to see in the pictures online. This may have had something to do with it. Reversing them now.

 

[axl]

Hi guys! just finished my build, gssl rev11 with 2180b vca, i was wondering, anyone knows what kind of voltage should I have on TL074  pin 1 7 8 14 in order to be sure that all works good?
Just want to know to understand if is all ok in my built, seems work fine but who knows!
I get alot of noise when make up pot is over 3/4 is that normal?

Thanks
Axl

 

[cray]

Hello .
On my Gssl one led is installed on the front panel.
I want to add one more led  inside the meter


is  a good idea to put another one  in serial with the one installed? or  better in parallel?

Thanks in advance!

 

[gyraf]

..add further led's in series - that way you use the same current (and drop less power in the series resistor),  we don't have too much reserve here..

Jakob E.

 

[snaper]

Quick question guys :  can I use a 2x17V 20VA toroid?
The local store has only 2x14 or 2x17

 

[Gustav]

Quick question guys :  can I use a 2x17V 20VA toroid?
The local store has only 2x14 or 2x17

I always thought "quick question" was a weird thing to type. It adds to the length of the communication while adding nothing to the content. It makes sense to stick your head into someones office and start with "quick question", so they know how long you'll be talking for, but in writing, the length of the text is obvious.

Answer is yes, you can use the 2 x 17V trafo.

Time for coffee!

Gustav

 

[snaper]

Quick question guys :  can I use a 2x17V 20VA toroid?
The local store has only 2x14 or 2x17

I always thought "quick question" was a weird thing to type. It adds to the length of the communication while adding nothing to the content. It makes sense to stick your head into someones office and start with "quick question", so they know how long you'll be talking for, but in writing, the length of the text is obvious.

Answer is yes, you can use the 2 x 17V trafo.

Time for coffee!

Gustav

Thank you Gustav!
Actually I'm working as an export manager, and the expressions : "just a quick question" is very common in hear...

 

[greyskull]

Hi guys. I appreciate one has to search first, but trust me I have!

My gssl has worked perfectly for years. However the other day I removed it from the rack at the studio and took it home, and it now appears to have developed a rather annoying white noise hiss on one side.

I initially put this down to a loose ground on the output xlr which I repaired, but the noise persisted. I swapped, and replaced the vcas but no joy. I've checked with a fine tooth comb, and can't find any shorts or loose connections, and other than this hiss/ pink noise, the unit functions perfectly. The only interesting thing to note , is that if I increase the make up gain, at a certain point the noise fizzles out.

Any ideas? Many thanks in advance

 

[up_right]

Hello,

I just built a GSSL and realised after troubleshooting the the 78L12 & 79L12 regulators were switched. I switched them back but none of the controls work. Audio passes through however.

What is the worse case scenario? Did I fry a regulator or something else down the line?

Thanks

 

[Gustav]

Hello,

I just built a GSSL and realised after troubleshooting the the 78L12 & 79L12 regulators were switched. I switched them back but none of the controls work. Audio passes through however.

What is the worse case scenario? Did I fry a regulator or something else down the line?

Thanks

I just replied to your mail which did not contain the info about switching the regulators back.

Still worth following my advice from the mail.

Your issue may not be related to the regulator at all, so verifying voltages (no ICs in) is still fundamental.

SC jumper may be wired wrong, bypass may be wired wrong, TL074 may be gone.

Just got another mail from you while replying here...(lets stick to the forum from now on to avoid more confusion) asking how to check voltages.

Google "pinout 79L12", check DC voltage on output pin with reference to ground. Repeat for the rest of the regulators.

Gustav

 

[up_right]

Thanks for the info Gustav, remove all IC's and test.

However, I still am unable to find information in these forums about how to check the voltages.  Does anybody have a link?

Are these the voltages I should testing?