mic to speaker circuit

[audioguru]

As an update... using the board layout that Boncuk provided I was able to resolve my problems. At this point the pickup on the mic is extremely sensitive and has resulted in temporary deafness.

Then why didn't you use its volume control?

I've adjusted the gain down to the 20 as provided by the op amp but would like to make this an adjustable value. 200 will work in certain situations but for the most part I'd be looking at a range of 80-150 for my application. Would using a trimmer cap accomplish this?

The gain is not adjusted with a trimmer capacitor. It is adjusted by replacing R3 with a 1k trimmer resistor in series with a resistor.
But why don't you use its volume control instead of changing its gain??