GSSL HELP THREAD!!!

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HyprDrivr

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Nov 5, 2020
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Hello friends!

I just finished my GSSL, and i thought i would share some observations.

I had some problems with output on the right side being louder than the left side that took some time to sort out. Turned out there there was a TINY bridge of copper, no thicker than a hair, left on the pcb itself between pin1 and pin2 on the NE5534 in the DBX can emulator. I got the board from PCBGrinder and the board is stellar otherwise and i couldnt find any info about anything similar, so i think its just bad luck on this board but i just wanted to share if someone encounters the same problem.

Because the global shortage of THAT chips i have built it with CooolAudio V2181. Earlier in this thread there are some spread out posts on what modifications are called for to make it work, but if anyone is interrested i could collect them all in a post.I dont know if anyone else has reported a fully working one with V2181 VCAs.
 

labak

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It really depends of what board revision you get from PCBGrinder... I do not know at what board revision we are now...If the resistors before the input of the channel's VCA are labelled 15k instead of 27k, it's a +10 years old board....
 

gyraf

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There's version number on copper side of main pcb

vca's got 27K input current resistors starting from rev#09, sometime late 2006

most current version is #12
 

babaorum

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gyraf

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Turbo switch wiring belongs in the thread about add-ons, I think (and has been answered several times over there iirc)

/Jakob E.
 

babaorum

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Ok but with this type of switch and without SSC do you think ? sorry to have posted here I apologize.
 

JAY X

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Jan 9, 2009
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Hi!

I'm trying to build this compressor. From the schematic, and correct me if i'm wrong, You can build it with original 202 cans or with the susbtitute circuit (2180/81 + 5534). So, just 2 build options, there is no third build option (2180/81 without 5534 buffer). ¿is that correct?

Jay x
 

Potato Cakes

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You can use a quad VCA adapter:


It still uses an OPA604/NE5534 for a buffer.

I'm not sure what you mean exactly by options, as there is a vast array of various mods to this circuit. Are you just asking about the VCA control? I don't know how many options one could want pertaining to the gain reduction parts for a VCA style compressor.

Thanks!

Paul
 

JAY X

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You can use a quad VCA adapter:


It still uses an OPA604/NE5534 for a buffer.

I'm not sure what you mean exactly by options, as there is a vast array of various mods to this circuit. Are you just asking about the VCA control? I don't know how many options one could want pertaining to the gain reduction parts for a VCA style compressor.

Thanks!

Paul

Hi!

I was reffering to the fact that the CV buffer to the vca is non inverting, as usually in most VCA circuits it is inverting, with R2/R1values of say 10k/100k. Anyway, i understand now, it is part of the particularities of this compressor. Thanks a lot!

Jay x.
 

Aprillegion1993

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Apr 13, 2021
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Hello,

I am a complete newbie to building electronics. I took up this project to build the gssl from gyraf and thanks to the insights from this forum i have almost finished the build. I have encountered a problem where my makeup gain doesn't work entirely. I am using pushbuttons for bypass and power on/off functions. I saw in the schematics in the gyraf build page that there are two connections (pot A and pot B) that go to the bypass poti. Since I am using the pushbutton, I used the schematic i have attached for making the connections.


1622443814806.png

But I see there are two connections missing between the bypass switch and control PCB when compared to the schematic from gyraf below. And i believe that this is the problem that is not letting makeup work.
1622443791745.png

I read through the forum a lot and wasn't able to find the needed information. Would be great if y'all can help me final the final piece to my puzzle. Thanks
 

HyprDrivr

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Nov 5, 2020
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Those points need to be connected to engage the makeup gain.
It looks like if you use that schemo you have to bridge it and makeup would be engaged even when bypassed. I belive the Gyraf info states that the original works like this
 

krabbencutter

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Jul 11, 2018
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I've finished building my GSSL yesterday and it seems to work quite well :) Thanks gyraf!
The only issue I struggled with, was that my threshold didn't seem to be working. Turns out I overlooked the junction between the 470R and 10K resistor at pin 3 of the sidechain VCA.
There's also an issue in the schematic I think: the 1M resistor in the feedback path of the third TL074 is floating on one end.

Some notes about my build:
- since I'm a Eurorack person, I'm running audio & sidechain from the same +/-12V PSU. Might not be ideal, but it works for now. Just to be safe though I've laid out the PCB so that both circuits could be powered independently in the future.
- I didn't have any tantalum caps around so I just used film caps on the release. Seems to work fine as far as I can tell, or could this be a problem?
- DIP14 sockets work quite nicely for the 2181s.
- Input/Output stages will go on a separate PCB and I'll definitely add a sidechain filter as well.
- not sure if I'll add rotary switches, because many SSL comps tend to sit on the same setting for eternity :D
 

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Aprillegion1993

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Apr 13, 2021
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Those points need to be connected to engage the makeup gain.
It looks like if you use that schemo you have to bridge it and makeup would be engaged even when bypassed. I belive the Gyraf info states that the original works like this
Thank you so much. I shall do this.
 
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Just looked at the CRC board parts list. Could the resistors on that board be smoking because they are 1/4 watt instead of 1/2 watt?
Hey brother. I was building the gssl and I kinda got all the parts. I'm not able to get the that2181 anywhere I checked all my local retailers and online shops including Profusion mouser and everything. But still I'm not able to get it. I only need that ic to finish the project. Can anyone help me?
 

calaverasgrande

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Jan 15, 2015
Messages
54
Rats, I knew I should have snatched some 2181 when I did my Mouser order for the GSSL a few months ago.
But I like to spread out my parts purchases. Thought by the time I need the VCAs I'm sure some other needs would have come up.
Well now I gotta get in line.
 
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