James HE,
I use filters to clean up my tracks like most of the other post responses. I mainly use band pass filters to clean up stuff. Just think of it like this: a band-pass filter allows a certain "frequency band to pass" unchanged. So a high-pass filter allows "high" frequencies to pass unchanged while cleaning out low frequencies. Low-pass filters allow "low" frequencies to pass unchanged while cleaning out high stuff.
Uses. It depends on the music, but I use a high-pass filter (set from 75-120 Hz) on background vocals, lead vocals, hi-hats and other cymbals, snare drums, rumbling guitars and thick keyboards. It will clean up the mix and get rid of unnecessary low frequencies to clear space for the bass.
I use low pass a little less often. But I will usually use it on bass, kick drum (depending) and other real low stuff to take out unnecessary highs (usually, above 10 kHz is totally unnecessary for many of these instruments). Remember, this is just a ballpark that is dependent on how you recorded it and the style of music.
After using band-pass filters, you can then use other eq's to lower or raise other frequencies.
I hope this helps.
[This message has been edited by Rev E (edited 03-23-2000).]