Hi there, hope everyone is having a great xmas season 
I am designing and building a VCA based compressor for a university project.
i have got most of my information for the compression stage and am now looking for circuits for my input gain.
I want a preamplifier circuit that can boost a mic level to a line level and also act as an input gain stage for line level signals to either increase or reduce gain.
I have a few questions;
what are standard gain ranges for preamps? As i understand it I need at least 60dB of gain in order to amplify a mic level signal to a line level signal my logic coming from
~1.2v (line rms) / ~2mv (avg mic) = 600 = 56.6dB
are there any good but not too complex designs out there i could have a look at in order to get my head around the theory . i have designed a basic preamp in TINA pcb simulator but when i attempted a gain of 600 the initial input was quite wonky before it settled out on my simulations, obviously not desireable
any sites pertaining to good circuit design would be good also, i have designs for a lot of the stages (theoretically), but putting these into practice is proving tricky.
thanks for any help given
Nick .
I am designing and building a VCA based compressor for a university project.
i have got most of my information for the compression stage and am now looking for circuits for my input gain.
I want a preamplifier circuit that can boost a mic level to a line level and also act as an input gain stage for line level signals to either increase or reduce gain.
I have a few questions;
what are standard gain ranges for preamps? As i understand it I need at least 60dB of gain in order to amplify a mic level signal to a line level signal my logic coming from
~1.2v (line rms) / ~2mv (avg mic) = 600 = 56.6dB
are there any good but not too complex designs out there i could have a look at in order to get my head around the theory . i have designed a basic preamp in TINA pcb simulator but when i attempted a gain of 600 the initial input was quite wonky before it settled out on my simulations, obviously not desireable
any sites pertaining to good circuit design would be good also, i have designs for a lot of the stages (theoretically), but putting these into practice is proving tricky.
thanks for any help given
Nick .
A great place for you to start would be the JE-990 Discrete Op-Amp (DOA, a horrible acronym for a brilliant piece of engineering...) of Deane Jensen, the founder of Jensen Transformers, one of the premier design/production facilities for high-resolution audio transformers used throughout the pro-audio world.
The John Hardy Company is probably the best known supplier of the JE-990, and also produces a range of pro-audio mic pre-amplifiers based on Jensen transformers and the JE-990. He has some nice documentation, including the JE-990 schematic here:
http://www.johnhardyco.com/pdf/990-2007.pdf
John Hardy posted some useful comments on DIYaudio here:
http://www.diyaudio.com/forums/soli...n-je-990-op-amp-deane-jensen.html#post1285335
Good luck with your project!
The John Hardy Company is probably the best known supplier of the JE-990, and also produces a range of pro-audio mic pre-amplifiers based on Jensen transformers and the JE-990. He has some nice documentation, including the JE-990 schematic here:
http://www.johnhardyco.com/pdf/990-2007.pdf
John Hardy posted some useful comments on DIYaudio here:
http://www.diyaudio.com/forums/soli...n-je-990-op-amp-deane-jensen.html#post1285335
Good luck with your project!
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