After reading all the whinging about foobar2000's equalizer, its sharp transition bands, and consequent ringing, I've decided to attempt to put together a minimum-phase parametric equalizer. Unfortunately, my Google-fu is weak on this topic. Any suggestions on where to start learning?

So far, it seems like the way to go is with IIR filters, but I'm at a loss on how exactly to calculate the co-efficients. I'm not extremely strong with the math, but I'm willing to put the effort in to learn, provided I've got a source that's going to give me the information I need to do this.

Apparently my attempt at this (foo_view) has disappeared almost entirely from the internets. Amazing. I wasn't even sure that was possible. At least, it got deleted from the fb2k forums somehow!

Anyways, I based my work on this. It won't give you terribly good band accuracy at high frequencies, but very little will in an IIR implementation. As long as there's an accurate frequency response plot to show the user, it shouldn't be an issue. It's obviously minimum phase. Stability of multiple bands should be assured with a cascaded implementation in double precision.

For details on IIR implementations, google cascaded vs parallel form, direct forms I/II, etc. It's easier than it sounds - most of the dirty work is in manipulating the coefficients nicely.

Maybe this is of help:
Robert Bristow-Johnson's biquad filter cookbook

Cheers!
SG

Thanks Sebastian. Axon already linked to that document though!