SSL 4K G-Series Mic Preamp

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alexc

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Very nice work  there :)

I'd be really interested in putting a couple of these together just to measure them!
 

signalflow

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Resurrection time.

Did anything ever come of this project once the prototypes were ordered? All docs seem to be removed except for the original schematic provided by Whoops. Curious to know if any were built or PCB's made?

Thanks,
Casey
 

Whoops

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signalflow said:
Resurrection time.

Did anything ever come of this project once the prototypes were ordered? All docs seem to be removed except for the original schematic provided by Whoops. Curious to know if any were built or PCB's made?

Thanks,
Casey

New developments here:
https://groupdiy.com/index.php?topic=42552.660
 

signalflow

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Whoops said:
New developments here:
https://groupdiy.com/index.php?topic=42552.660

I've seen the thread but wasn't sure he used the actual G+ schematic. He mentions the transformerless E series preamp(149) which has 2 matched transistor pairs instead of the 1 pair the G+(291) uses.

Kevin said:
To clarify a bit I use

SSL 82E149 transformerless thats formerly also a E Series but with two LM394, The G series is a bit similiar from that circuit design.

SSL 82E01 Transformer based with JT115K-EPC like the original used on the cards

and the SSL 9k found in the SSL tech docs

I will use switches for gain for all my designs

I PM'd Dustbro but no response.  The G+ does "resemble" the 9K. Like they got to a point and just said ...meh. I'll stare at if for awhile and see if it goes anywhere. My main question was the gain switch wiring. Seems that will be a bit of experimentation if it ever gets that far.

-Casey
 

Whoops

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signalflow said:
I've seen the thread but wasn't sure he used the actual G+ schematic. He mentions the transformerless E series preamp(149) which has 2 matched transistor pairs instead of the 1 pair the G+(291) uses.

I see what you mean...

You should ask that to Kevin in the relevant thread.

This thread has no activity since 2017, so it's better to consider it dead and move on to the new developments.

I still have some dustbro pcb's, pm me if interested
 

signalflow

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Ricardus said:
Is VR1 that drive circuit that was being talked about earlier in this thread?

No. This looks to be a CMRR adjustment.

The circuit you're referring to is the VHD(Variable Harmonic Drive) circuit found on their newer rack gear and Duality console.

-Casey
 

signalflow

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Having just seen the docs today, thanks to Whoops, I may have mistaken your question. The added Pot on the front panel is an output level control. What I thought you were talking about was the trimmer located right after the diodes at the input.

-Casey
 

Ricardus

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signalflow said:
Having just seen the docs today, thanks to Whoops, I may have mistaken your question. The added Pot on the front panel is an output level control. What I thought you were talking about was the trimmer located right after the diodes at the input.

-Casey

I was talking about the trimmer. But I don't see any documentation about where the output pot goes in any of the stuff I have.

But when adjusting the trimmer pot for CMRR, what exactly and I measuring and comparing? Am I just running a sine wav into it and matching signal levels on either side of the pot?
 

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