yes, I've played around with zsa.freqpeak~, but it seems to me that the forbidden planet filter is giving the amplitude for each bin, rather than frequency amplitude pairs. So I still need to know which bin to keep after the filtering. I'm sure this is painfully simple, but I so seldom do spectral processing...
I've tried using a threshold-based spectral filter, as well, but this doesn't quite get at the idea, because the input is always changing, so I don't get the sort of break down to a few, isolated sines, that I'm after. I know this isn't acoustically "realistic", but what I want is to take a sort of snapshot of the spectrum, at some point in the development of the sound, and use that as a template to filter the sound down to a few sines -- to kind of artificially decompose it down to a few sustaining pitches.
J.