sir is this really a working circuit? if i do the circuit you've shown can i use TL071CP for the op-amp? and can i use an 8-ohm 1w speaker for the output? for the potentiometer, can i use an ordinary potentiometer? and i posted a picture of the electret mic. does electret mic has polarity? c2,c3,c4 are electrolytic right? what is their voltage rating? and for the resistors are they 1/4W? sorry for the many questions sir.