Op Amps: Unwanted Oscillations

Greetings,

I'm guessing this is a fairly common issue and I've looked up all the info I can on it but I still have questions.

When trying to build a basic electret preamp I have problems with oscillation. Without an oscilloscope I'd say it sounds 'jagged' like a really spiky sawtooth or similar. The solutions I've read about tend to involve putting capacitors in various places such as in the feedback - but I also notice that this dampens the sound and that is a problem since I want it to be sensitive well into the ultrasound range (I'm using TL084s which should work up to about 1MHz)

The only thing I've found that makes a difference is throwing more and more bypass capacitors at it, but we're talking 10s of milifarads for a decent result - that must represent a hell of a current draw??

Anyway - I'd be grateful if anyone could shed a bit more light on what causes these problems and how to deal with them properly

 

Sorry for the delay (and thanks for the quick responses).

Anyway, it was some playing around on a bread board so no schematics. It was just the very basic inverting and non inverting designs that you can find anywhere. I was using 68k resistors for the + input divider, and following it with a buffer (output fed back to - input, no other components) and 10uF coupling capacitors at each point (3 in total).

What I did find was that lowering the resistor used to power the electret made a big improvement (was initially using 10K).