Isolation between microphone and amplifier

[zerodegreec]

I have a project that's killing me. I have a microphone that I MUST completely isolate from the amplifier its sending a signal to.

I have a speaker and mic that I cannot separate the Neg (-) of the Mic and Speaker. If I make up a powered circuit to power the FET of the electret mic life is good and everything works. As soon as I connect ANYTHING to the speaker side I have problems with feedback.

So is there any way to isolate both sides of this drawing.

 

[Raza]

If I make up a powered circuit to power the FET of the electret mic life is good and everything works

Me confused, if every thing works then what is the problem ?
Which MIC you want to connect, Electret or Dynamic ?.
Are you using Pre-Amplifier ?. Or how you are connecting the mic to the amplifier ? Best is, instead of Block Diagram, upload the schematic.