I want pre-amp schematic with A s/n ratio 92 db or more

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If you want your preamp to be able to accept 2Vrms at it's input, then if the input noise must be lower than 92dB, this will equal:

2 x 10^-4.6 / sqrt(20KHz (bandwidth)) = 349nV/sqrt(Hz)

It's hard to design something so noisy. Every opamp known to me has an input noise lower than 40nV/sqrt(Hz), take you pick, NE5534, or opa227 (both about 3.5 nV/sqrt(Hz)), opa134 (about 8nV/sqrt(Hz) ? ).

Edit..: oops allmost forgot: Nelsons MOSFET preamps will meet this criterium too. BTW what is the EIN of a IRF610? something like 20nV/sqrt(Hz) ?


But if you want 92dB S/N for a 2mVrms (max input) preamp, you'll have a challange... you'll have to build a discrete BJT preamp, eg. a 6 transistor symmetrical input stage with Vbc = 0Volt and 300uA Iq each transistor, or a handfull 2SK170's in parrallel...

Goodluck,
Thijs
 
A low noise power supply is vital to get good performance of a preamp.

Also pay attention to PCB layout and internal wiring to avoid ground loops.

Will you use discrete components or use Op-Amps?


The Aleph P mentionend in this thread is an example of a good amplifier.
 
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