Simple head amp for electret capsules

Over in my FET measurement thread I've been playing with "electret microphone" FETs - representative of the sort found built in to some capsules. The main difference between these and other condenser-mic JFETs is a built-in bias "resistor" / diode, which means you don't get to set the bias current externally (the circuit has to run with Vgs close to 0V, so the operating current is basically the Idss value). I think there's room in the world for a circuit somewhere between the... Read more