GSSL HELP THREAD!!!

[chrispbass]

Hey guys.

Just a quick question about my gssl:s psu.

I'm getting the negative rail spot on -15v. But the positive rail is about 3v. And it traces back to the bridge-rectifier.
The AC current is fine I think (16.6v)

Why is that? What have I missed?

Tried to search the forum and Google but nothing, and when I find something that could be it here on prodigy I've got limited access for some reason..


Cheers

Are your transformer secondaries wired properly and giving you 16 0 16 ac volts approx (depending on your tx)?

Are you getting approx 32v across the legs on the ac side of your bridge rectifier(or 16v referenced to 0v on each leg)?

Double check everything, cap polarity, orientation of bridge rectifier, all 4 regulators.Should be 2 x 10 ohm resistors fitted...are these correct value?

Are your wire links fitted on the board?

if all ok, perhaps try unsoldering your 7815 and re-check +ve voltage at bridge rectifier.

see if that gets  you your 16v back. if not, then double check 7812 reg and unsolder that and check again.

i'm not pretending to be an expert, but its so easy to miss something...

Hope that helps a little...good luck.

 

[XeNoMoRpH]

I have a quick question; what is the unity gain mod?

I've seen references to it on both Jakob's site, and other sites. But I haven't seen an explanation of it.

Sorry if this is an overly stupid question.  :-\

 

[ncoak]

unity gain mod involves replacing the two 15k resistors near the output section of the main board with 27k resistors - this compensates for the 6dB or so difference between input and output inherent in the original design.

 

[XeNoMoRpH]

Aha, thanks a lot for the explanation!

 

[kaptensarkasm]

Hey guys.

Just a quick question about my gssl:s psu.

I'm getting the negative rail spot on -15v. But the positive rail is about 3v. And it traces back to the bridge-rectifier.
The AC current is fine I think (16.6v)

Why is that? What have I missed?

Tried to search the forum and Google but nothing, and when I find something that could be it here on prodigy I've got limited access for some reason..


Cheers

Are your transformer secondaries wired properly and giving you 16 0 16 ac volts approx (depending on your tx)?

Are you getting approx 32v across the legs on the ac side of your bridge rectifier(or 16v referenced to 0v on each leg)?

Double check everything, cap polarity, orientation of bridge rectifier, all 4 regulators.Should be 2 x 10 ohm resistors fitted...are these correct value?

Are your wire links fitted on the board?

if all ok, perhaps try unsoldering your 7815 and re-check +ve voltage at bridge rectifier.

see if that gets  you your 16v back. if not, then double check 7812 reg and unsolder that and check again.

i'm not pretending to be an expert, but its so easy to miss something...

Hope that helps a little...good luck.

Thanks.
I figured it out the day after. I wired the secondaries wrong.. Now all the voltages are spot on!  ;D
Now I know how NOT to assemble my next gssl, that will say not between 00.00 and 05.00...

Now I got another problem but I will post that in a new message if I cant figure it out by reading the whole thread  :

Thanks again!

 

[Harpo]

unity gain mod involves replacing the two 15k resistors near the output section of the main board with 27k resistors - this compensates for the 6dB or so difference between input and output inherent in the original design.

.. in an unbalanced-out config (XLR-pin 3 on output disconnected).
Difference in a balanced-out config, as shown in the GSSL schematic, isn't -6dB but  +0.915dB with perfect parts.
Either replace the 27Ks in front of the audio-VCAs with 30Ks or replace both 15K feedback resistors with 13K5 resistors (2x 27K in parallel = 13K5).

 

[kaptensarkasm]

Is there someone from Sweden who wants a BOM for the GssL at ELFA?

PM me if you want it.

 

[kosty]

I managed to build the gssl incl turbo and SSC board.

I have faced several problems :

- the compressor acted very weird. I accidently connected the ribbon connector in reverse.
After correcting this the controls were OK.

- The signal sounded very muddy with almost no high end ! The problem was the 33pf capacitor on the input NE5534's feedback loop. Mouser gave me wrong values one's (33nf) which gave me a 220hz low pass ! Removed this cap and the sound is clean !

The last problem I'm facing is that I have a leak between left and right output !
Meaning :

- if I send a 1khz sine wave to the RIGHT input I have a A clean signal only on the right output.

- if I send this signal only to the LEFT input, the left input is normal BUT i have a signal also on the RIGHT output with a very high level (input of my interface is clipping !)

- everything happens in bypass mode.

- i removed the turbo and ssc mod from the signal flow

- i swapped both input opamps, vcas and output opamps, as well as the tl072 from the sidechain.

- 15v is 14.78 and -15v is -15.2

- if i remove the left vca the problem is gone ! (when sending only into the right input)

- I tried tracing the signal with my oscilloscope but it's not that easy visualizing anything on some part of the circuit.

- i have a very clear almost rectangular waveform with 1khz on the lower end of the 680k resistor next to the right vca when only left input is fed. (it's the 1 MOhm one I replaced because of that2181A)

- if I remove the NE5532 of the left input. Nothing arrives on the left input (logical).

I suppose it's a solder bridge somewhere but I have no idea where to specifically look. No obvious bridges by looking.

Any suggestions?

For those facing the same problem : The solder joint was between resistors 470R and 47K in the output section after the left VCA and before the right NE5532.

Just need to optimize the resistor values for correct ratios now !

 

[schrobbelbop]

Hi!

I've noticed my left channel is oscilating on its output.. i only hear it when connect to a digital mixing desk (digico's)
at analog desks it's not hearable, but i see the vu meter lit up a bit. so it looks like a little potential on its output.
the amount and frequency of the oscilating ssl is depending on it's makeup gain pot.
anybody knows where to go searching?
I already swopped all vca's and ic's.... what to search for next?

thanks!

foud the problem, after 1 year of using the unit.... forgot a 100pf cap in it's output circuit.. WHOOPS

 

[gyraf]

thanks for posting solutions - makes this thread much more valuable for future use!

Jakob E.

 

[Dr_J]

Maybe a new thread only containing problems with solutions would be great!?
Like a kind of problem archive.

 

[Holiveira]

Hello,

In the list of components that are needed are 9 capacitores100p 5% 100V Monolithic. I noticed that there are 10 mounting positions for these capacitors.

It takes 10?

Thanks

 

[XeNoMoRpH]

Yes, 10. I found out the hard way

 

[Bob1991]

I'm experiencing some kind of strange problems with my GSSL since I have my turbo board installed. The make-up gain knop doesn't work anymore, the GSSL's output is at the lowest make-up gain volume when compression is on. Voltages etc. on the turbo board are okay.

Also, when listening very accurately, I hear some kind of distortion in the higher frequencies. For example: I'll play a quiet piano track to the GSSL, and i can hear audible distortion when I'm using the highest 10:1 ratio setting. This could be some kind of over-compression artifact, but I think it's kinda strange that it also distorts when I bypass the compressor (with standard lorlin rotary switch), and have the (bypassed) compressor on the 10:1 ratio setting. The two other ratio's do not audible distort the sound.. Oh, and when i turn the threshold to the right/'compress nothing'  the distortion also dissapears.. But with threshold to the left/heaviest setting, it still distorts when in bypass and ratio on 10:1. I don't know if it was already distorting before the turbo mod, because it is quite hard to hear..

I am using 2181LC vca's, which have a little higher THD, but I don't think this could be cause? Turning the VCA trimmers makes no difference to the sound..

 

[Dr_J]

Hi Bob1991,

first make shure that the main board is working correct when bypassing the TURBO board!
I had although some trouble with the TURBO-board...

Cheers!

 

[wimmy7986]

Hello Everyone.  This is my first post and i am very much a beginner, so please excuse my lack of knowledge...

The unit passes audio perfectly with no hums, no difference in volume..  My problem is that none of the compressor controls are doing anything.  The makeup gain, and bypass are working great, but i have NO COMPRESSION.  After a few days of searching this thread and research, i figured I must've put a wrong valued resistor in the sidechain section, but after checking all of them, they all seemed to be the correct values.  I checked for shorts and didn't find anything wrong.  Can anyone point me in a good direction to troubleshoot this?  I'm out of ideas....  Thanks

 

[synnys]

Hello Everyone.  This is my first post and i am very much a beginner, so please excuse my lack of knowledge...

The unit passes audio perfectly with no hums, no difference in volume..  My problem is that none of the compressor controls are doing anything.  The makeup gain, and bypass are working great, but i have NO COMPRESSION.  After a few days of searching this thread and research, i figured I must've put a wrong valued resistor in the sidechain section, but after checking all of them, they all seemed to be the correct values.  I checked for shorts and didn't find anything wrong.  Can anyone point me in a good direction to troubleshoot this?  I'm out of ideas....  Thanks

I had the exact same problem with my first unit. read from page 240..

Did you make sure you didn't forget the little jumper on the control panel (next to the connections for the panel meter)

 

[wimmy7986]

Hello Everyone.  This is my first post and i am very much a beginner, so please excuse my lack of knowledge...

The unit passes audio perfectly with no hums, no difference in volume..  My problem is that none of the compressor controls are doing anything.  The makeup gain, and bypass are working great, but i have NO COMPRESSION.  After a few days of searching this thread and research, i figured I must've put a wrong valued resistor in the sidechain section, but after checking all of them, they all seemed to be the correct values.  I checked for shorts and didn't find anything wrong.  Can anyone point me in a good direction to troubleshoot this?  I'm out of ideas....  Thanks

I had the exact same problem with my first unit. read from page 240..

Did you make sure you didn't forget the little jumper on the control panel (next to the connections for the panel meter)

Hey thanks for getting back to me.  It must've been a cold solder joint...  I reheated all of the solder joints, plugged it in, and its working now

 

[braeden]

Hello!
I just finished my GSSL, there are a few noisy switches however. I've analysed it with an oscilloscope and it seems to be distorting/adding to the signal somehow when I change the value of the switch. This doesn't happen with the ratio switch, only the attack and release switch which is particularly noticeable.

Any suggestions?
Thanks!

 

[gyraf]

Yes, distortion change is expected when changing timing. The lower the frequency and the faster the timing, the higer the distortion.

(goes with being a compressor, sorta')

Jakob E.