GSSL HELP THREAD!!!

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MaxSquare

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Dec 22, 2017
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3
Hey, guys and girls. Is there any way how to use Serpent Audio quad VCA (got mine pair as a gift) in regular GSSL build? What needs to be cut or changed? SOS
 

gyraf

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as we don't know what serpent put in there in the first place, we can't estimate that. Ask serpent perhaps?

/Jakob E.
 

rna

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Joined
Nov 20, 2015
Messages
21
I thought I would share my experience with installing the Cavendish mod by Expat Audio.
I have to admit I was skeptical of the difference it would make as it was a random thing to do during the lockdown.
But I have to say it really does bring something to the party!
 

calaverasgrande

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Jan 15, 2015
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65
FYI Banzai seems to have THAT 2181BL08-U for anyone scraping bottom to find them.
I just put in an order for an even dozen though the price is a couple dollars more than Mouser.
Mouser can't sell me what it hasn't got.
 
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Wingong

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Aug 10, 2017
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Boston, MA, USA
Hey all, I just finished putting together a rev 7 board (I'm still waiting on the 2181s but this gives me time to double check for problems) and as far as I can visually tell everything looks right and plugging into power I get all good voltages at each IC socket. That is except the side-chain 2181s where the negative rail reads around -8.5 volts. So I assume there has to be something up with either the 3K9 or 10K? Both the TL072 and TL074 read proper +-12v and the positive rail reads 12v on the 2181.

Will
 

gyraf

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The -V for the 2181 is more like a current bias, not a "real" supply pin

-8.5V at the vca pin sounds about right..

/Jakob E.
 

lekterdead

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May 12, 2021
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Location
Mexico
I don't know if this has been asked before but couldn't find any answers so far searching in here(or found parts that doesn't seem to be in stock anymore), What toroid are you using for 120AC? Something from mouser or digikey wold come in handy
Thanks :D
 

1wildthing

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Jan 27, 2021
Messages
13
Hi guys, I’ve built the GSSL but no sound is coming out from it. It seems that the signal is not passing through it since the meter moves only when I turn the gssl on. The voltage is correct as the power led works and the dc at -/+ 15v jumpers is correct.
Could you please suggest me where to start to solve this problem? I attach some pics of my built
 

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Script

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Nov 26, 2008
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Check for correct orientation of op amps.

Feed a steady signal into the unit. Could be from signal generator or just a single note held on a loop from your DAW, but not music . Then measure AC between ground and input pins 2 and 3. Then take schematic and follow signal, measuring at all nodes on the way.
 

Juanaca

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Dec 8, 2019
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69
hola he construido un gssl rev11, tengo dos problemas aunque no son muy importantes, el primero el filtro sidechain no es demasiado efectivo, creo que hay una modificación que se llama turbo pero no se que hace realmente, es duplica el oamp 074 y un vca ? el otro problema es el vúmetro de 1ma comprado en donaudio, este vúmetro parece ir demasiado disparado en cuanto al movimiento de la aguja, ¿qué modificación hay para mejorar y la abuja va más suave y con menos con menos recorrido? Gracias
 

Script

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Asking in English might help us understand you.

The sidechain filter and the turbo mod are two different things.

As for your 'abuja' ;) , there's a trimmer for that. Also there's dedicated VU board available from Expat Audio. And you could search for 'GSSL' and 'meter' and 'calibration'. There's a calibration guide somewhere on this forum -- written by SSLtech, I think.
 

1wildthing

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Joined
Jan 27, 2021
Messages
13
Check for correct orientation of op amps.

Feed a steady signal into the unit. Could be from signal generator or just a single note held on a loop from your DAW, but not music . Then measure AC between ground and input pins 2 and 3. Then take schematic and follow signal, measuring at all nodes on the way.
Thanks! I’ve found a bad solder on the pcb and and I’ve replaced a bad tl074. Now the sound comes in and goes out but it doesn’t compress. On the control board the only pot that works is make up gain and even the meter is not moving.
The bypass seems to work.
What may I check to find a solution?
 

Gustav

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Thanks! I’ve found a bad solder on the pcb and and I’ve replaced a bad tl074. Now the sound comes in and goes out but it doesn’t compress. On the control board the only pot that works is make up gain and even the meter is not moving.
The bypass seems to work.
What may I check to find a solution?

You write that the bypass seems to work, but to make sure that you do not have a miswired bypass causing the problem (symptoms fit), could you share the reasoning behind the conclusion?

Gustav
 

1wildthing

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Jan 27, 2021
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You write that the bypass seems to work, but to make sure that you do not have a miswired bypass causing the problem (symptoms fit), could you share the reasoning behind the conclusion?

Gustav
Hi Gustav thanks for your reply, actually I'm not expert. I followed this scheme but I didn't wire the led this way yet. I'm supposing that it's working because when the bypass is in off position the makeup gain works instead when I turn the switch in on position the gain is not working anymore. For this bypass I wired a 3pdt On-off-On that I had in stock. Do you think this could be the problem?

download.png
 

HyprDrivr

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Joined
Nov 5, 2020
Messages
14
Just looking at the image of the bypass switch from the above post, it does not look like the wiring diagram you have posted. You have not incorporated the LED and one pole seems to connect to nothing.
I would remove that switch and start over.
I suggest not using the same color for all wires, just ads one more level of confusion when troubleshooting.
 

1wildthing

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Jan 27, 2021
Messages
13
Hi guys good news here! The biggest part of problems was created by 2 solder joints touching each other and by poles inverted on meter. Now it compress! 🙌
However since I’ve never used a real G compressor before I have a doubt.
when threshold goes on positive values (expander) the meter is not moving and knobs on command board don’t seem to affect the sound anymore.
Is this a normal behavior or is a new issue? 😰
Please forgive me for my boring questions.
 
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Gustav

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Hi guys good news here! The biggest part of problems was created by 2 solder joints touching each other and by poles inverted on meter. Now it compress! 🙌
However since I’ve never used a real G compressor before I have a doubt.
when threshold goes on positive values (expander) the meter is not moving and knobs on command board don’t seem to affect the sound anymore.
Is this a normal behavior or is a new issue? 😰
Please forgive me for my boring questions.

Your unit should not react when threshold is set above audio level - there is no "compressor to one side/expansion to the other" functionality, only compression over the set threshold.

Sounds like you have something weird going on, but we would need feedback on what happens to help.

Gustav
 

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