whats the best way to go about filtering out a single partial (a sine wave), because im having trouble. i dont know if its supposed to be here, thanks anyway for anyone that can give me some clues. id like it not have its phase or amplitude disturbed.

Are you wanting to do this within in a DAW/sequencer as a real-time effect or as some sort of pre/post-processing of a sound that can be saved a loaded into some external app for later usage? I'm grasping here because I've never really had to do this specifically, especially not in a DAW, but I would imagine you can do some of Fourier analysis and resynthesis techniques to do what you want. One thing you may want to try is basically do a fine resolution FFT so that you get the frequency and amplitude information, pull out the bin of the desired partial and resynthesize a time series waveform based on that. I know I've had to do something similar to this in a digital synthesis class I took a couple of years ago, and we were using CSound, so if you don't mind coding out a simple CSound program to do that, it should get you something close to what you want. Other than that, I don't know of too many tools for this kind of work.

People over at the KVR forums may be able to help you out as well.

Edit: Did some reading up on this sort of stuff while waiting for stuff to finish up at work and found something that might work for you and would be a lot more friendly to use than Csound's opcodes. It's designed to be a plugin into a VST host, so you'll need one of those (there's a number of free ones), but you might want to give this a try.

[Edited by - romer on September 29, 2008 4:07:53 PM]

the fft seems to be the best option, but i gotta learn how to use it properly.
thanks for the reply.