Arjay, if you reverse the capsule connections in a normal “true” condenser mic, nothing happens there, either.

Electrets are weird. It took some experimentation for me to figure out how an electret capsule behaves. My greatest confusion is around polarity of the signal generated. Does the electret act like a constant charge on a variable capacitor, same as a “true” condenser? Or does the effective charge vary as the diaphragm moves into and out of the electret field?

It appears the “charge” increases as the diaphragm approaches the electret film, so this isn’t a constant charge Q = CV situation, where if C goes up, V must go down. What is the voltage, anyhow? If you measure at rest, despite the constant electric field, there is no voltage between the electrodes. And what is the charge, Q? If you put a meter from diaphragm to backplate, no current will flow. Is charge zero? Thinking in these terms wasn’t getting me anywhere.

That’s why I think in terms of electrons migrating. We have a bunch of electrons trapped in a plastic film, which create a negative electret field around the backplate. Bring the diaphragm into the electret field, and electrons from the diaphragm will be repelled to ground, so the diaphragm acts as if it is positively charged. Bring the diaphragm closer, and the field and “voltage" increases. So does the capacitance, incidentally. Both effects increase the apparent negative “charge” on the backplate, which causes current to flow across the gate resistance of the FET, driving it negative. As the gate goes negative, the drain goes positive.

And that’s how I explain it to myself. If it turns out my Neumann, Shure, and AKG mics are wired backwards, or I’ve made a stupid mistake, I’ll have to revise my explanation. 8^) 

At least all my mics match, which is the important thing. Including Jules' OPA Alices with RK-12 capsules, which are outstanding mics, BTW.