GSSL (Great Studer Special Limiter)
« on: October 04, 2017, 11:16:39 AM »
Hi all

Beside the joke at subject title, I'm starting to build a project around few Studer eurocard laying around
I basicaly want to build a (G)SSL sidechain type , with a stereo balancing unit (twin sym/asy card, trafo/553x based) as studer VCA subcard (the very suder design version not the dbx version)
So I "just" need to put on a vero board the SC time and DC conditioner section, which I already draw and route with Kicad to have a acceptable layout to work with. For the moment it's a direct copy of the GSSL schemo

Question is simple for now.
What is the expected DC voltage scale at both CV (audio VCA control port as SC VCA control port) ? The VCA I have are set to 10dB/V but it's easy to change this...
For what dB/V is it set at GSSL ? 20dB/V as I read in some dbx202 datasheet ?
I also see NFB gain adjustement for CV at GSSL data/notes depending of 2181 or 202, but don't find any info yet about expected CV range and VCA control input sensitivities setting.

I think I can figure this out with measure, test and calibration, when everything will be wired together, still input appreciated :)

Attached the VCA sub card, I have enough to use it for audio and SC (I also have the other version with 2150, maybe for SC ?)
Just imagine line buffer before and after two of this card, as the GSSL SC after a third card.


Re: GSSL (Great Studer Special Limiter)
« Reply #1 on: May 05, 2018, 10:08:08 AM »
Hi all

Since this build is done and in service/evaluation at the studio.
So far it work well  :)

I added high pass selector in the side chain as send/return for outside SC processing

I have in mind a compression limiter mod, a DC control at sidechain that limit the gain reduction
I guess I can use selected zener for stepped action but I'll like it variable, what options do I have to perform this ?
Small voltage regulator like LM317L ? despite the voltage drop, how this will react to variable DC input ?
Scaled opamp for gain exceeding rail (limit) followed by opamp reducing gain for same amount ?