[sdiy] Low noise electret condenser microphone amp?

[Grant Richter]

Take a look at the Analog Devices AD797

http://www.analog.com/en/prod/0%2C2877%2CAD797%2C00.html

I used them for a metal detector project and they are very quiet.

> From: "Bert Schiettecatte" <bert at percussa.com>
> Organization: Percussa
> Date: Mon, 15 Nov 2004 23:33:59 +0100
> To: <synth-diy at dropmix.xs4all.nl>
> Subject: [sdiy] Low noise electret condenser microphone amp?
> 
> Hi List,
> 
> I've got a couple of panasonic microphone cardridges here
> (omnidirectional). They have some sort of preamp but I've found that I
> still need to amplify them by a factor of roughly 200x before they will
> pick up my voice from a reasonable distance (about 40cm). I built a
> simple amplifier circuit I found on the net, based on an LM324 op-amp.
> When I run the circuit by itself from a power supply it seems to work
> fine, but it also amplifies a lot of noise. When I include the circuit
> into a bigger microcontroller circuit I've been working on, I get even
> more noise that is amplified by the 200x gain opamp. Any ideas on where
> I can find a really good microphone amplifier circuit? It should be able
> to pick up sound 40cm away and amplify it to a reasonable level.
> 
> Thanks,
> Bert