References for mic preamp design concepts??

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crazytooguy

Well-known member
Joined
Dec 9, 2005
Messages
57
Hello all. I've been pouring over schematics for several different solid-state mic preamp designs, and have a lot of questions about the purpose and function of components and combinations of components. Can someone recommend a good resource that might explain the various elements of these circuits? I'm afraid my knowledge of circuits is pretty archaic - I understand tube circuits much better than SS. I get opamps and how they operate, but I've been looking at several SS mic preamp designs such as the SSL 9k, the Green, the Supergreen, and I'm unclear about a lot of the circuitry. An example - what is the function of the transistor and opamp in the first stage of the 9k? I assume it's a gain stage, but how do the actives and passives interact? I'm looking to get at an understanding of how these various circuit components wil ultimate affect the sound, and I want to breadboard these circuits to do some listening comparisons. I suppose I'm asking for a lot here - if I really wanted a thorough knowledge, I'd go get a BSEE :grin: Much too lazy for that, though. So, any good resources that can help me grasp these designs? Thanks!
 
the Greens are the same
and the greens and the SSL9k probably fall on the same side of the fence when compared to the tubes and DOA and other transformer stuff

why the transistors
well that's the subtlety and the detail
the 9 and the green use transistors in the early gain and imp change section
both of these are trafo-less

sideways
The F110 is a trafo step up to single, simple gain opamp ... yes there a an amp on the end that not average.
IF you want a trafo-less opamp unit with out the F110 issues and more gain then it is likely you end up looking to a transistor front with opamp like the 9k and green
OR
tailor a specific opamp and manufacture a Mic-pre chip like the 2016 and then refine it as many have tried.

This doesn't answer the direct question of
" ... what is the function of the transistor and opamp in the first stage of the 9k? "
it's all about details here
transistor arrays ... matching ... selection ... it goes on

gain stages and their faults do create the differences
also the small signals and termination of the mic and energy transfer is prone for the unexpected.

A BSEE may be required to detail this

however
a quick look at topologies can help to categorise and pigeon hole for a initial impression but it is the details that really split them up

there may be no fast track to knowledge
just keep circling the topologies and read and test and experiment
 
Thanks, Kev. Without the EE, I think the best way I can get a feel for circuit design is to breadboard some of these mic pre circuits, and tinker with them. I've set up a reasonable testing rig (o-scope, function generator, computer-based spec analyzer, etc.) and a means of auditioning circuits through my studio setup without blowing anything up, so I'm hoping to educate myself on the various elements of these circuits and their effects on sound quality. And I'll keep perusing all the topics on this forum; that alone has been very educational. :green:
 
Hi!

Look up the AES preprint no 2106 by Cohen. A good place to start when trying to understand this topology.

/Anders
 
What helped me and still does help me in trying to understand circuits is reading through Data sheets for certain opamps, especially the Applications information, as it will tell you what each component does within a circuit and gives you explanations and solutions to problems that arrize when implementing certain discreet components with opamps to make a working circuit....


Cheers
 
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