Try the cap from the input of the amplifier to the 9volt line
I expect , lots of noise probably because of power supply noise

Peter

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Noise in discrete components

I'm working on a 16f877 a/d project that reads audio from an electret(sp?)
microphone which has been amplified by an lm386 set for a gain of 100. The
mic itself seems to be low on noise, but the 10k resistor to V+ is a
standard carbon 1/4W variety and it seems to be producing excessive noise. I
conclude this based on the fact that I can short the mic and the noise
persists, but disconnecting the resistors will stop the noise. Test circuit
is below (use fixed-pitch font to view). Would a metal-oxide resistor help,
or are there other options?

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