The Buchla analog synthesizers contained filters to separate odd and even harmonics. They were primarily used in the synthesis of different types of instrument timbres rather than filtering acoustic instruments, but perhaps it's worth trying on your own in Pd.
http://www.buchla.com/historical/b200/images/296-large.jpeg
Best, Derek
On 12/25/10 6:47 PM, Achim Bloch wrote:
I was wondering if another way to achieve this goal could be to magnify the harmonics in a more « mathematical » manner, let's say, magnifying the bass drum harmonics frequencies if they are even, and the bass guitar ones if they are odd?