[sci.electronics] Microphone noise

tindle@ms.uky.edu (Ken Tindle) (07/27/89)

I'm having (very unexpected) problems designing a microphone amp circuit.
Gain is no problem, per se.  Audio I get easily; it's the noise that goes
with it I could live without.

Now I already know the signal directly off a dynamic mike is small, but
evidently the noise floor is close to the audio.

I'll have to admit that I don't know enough about the nitty-gritty details
of microphone function to understand what is happening.  Is there someone
out there who's jumped this hurdle in the past, who'd be willing to give
me some pointers?

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collinge@uvicctr.UVic.ca.UUCP (Doug Collinge) (08/02/89)

In article <12296@s.ms.uky.edu> tindle@ms.uky.edu (Ken Tindle) writes:
>I'm having (very unexpected) problems designing a microphone amp circuit.
>Audio I get easily; it's the noise that goes with it I could live without.

Mic preamps are pretty tricky for several reasons.  I suggest that you
rip off the preamp design from some existing mixing board.  For e.g.,
the Soundcraft mixers use a pair of discrete transistors as a front end
to a TL072 bifet opamp.
-- 
		Doug Collinge
		School of Music, University of Victoria,
		PO Box 1700, Victoria, B.C., Canada,  V8W 2Y2  
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