[sdiy] trying to understand amplification of an electret mic element

[dan snazelle]

normally when I want to add a lot of gain to something quickly, I grab a TL072 and use a resistor combination of say 1k to 1M.

However, with these microphone elements, things are all weird.

I started off as I understand you are supposed to by connecting the element to a 9v source through a 1k resistor. i tied the other end to ground. I took the signal out through a .1uf cap.

well, with the opamp as above, I got very little gain.

So I tried with a single transistor. (220k from collector to base, emitter to ground, 22k to +v and a .1uf cap out from the collector) 

 It was much better. But still not enough. ( i want it to be enough gain to pick up background noise, not noise directly at the element)
So I tried putting THAT signal through an opamp.

I got weird offset issues EVEN with a blocking cap. And it still didn't add much gain!

What is going on? I have plenty of experience working with REAL mic pre-amps but I have never made one from scratch before for an electret element.

its interesting and somewhat of a challenge because all other inputs I have tried (synth, line level stuff, guitar) all was very easy to add gain to.


thanks for ANY help.