Hi,
I recently used the principles shown here by Derek Holzer in a live performance, a lecture of the 6th book of the Odissea (Nausicaa) mp3 excerpt available at http://www.davidemorelli.it/04/odissea.mp3 sources: https://puredata.info/Members/dmorelli/patches/
Thank you Derek.
davide.
-----Messaggio originale----- Da: pd-list-admin@iem.at [mailto:pd-list-admin@iem.at]Per conto di derek holzer Inviato: martedì 15 febbraio 2005 17.48 A: pun chik Cc: PD-List Oggetto: [PD] resonant comb filter series
A comb filter is simply a very short delay with a high amount of feedback. It is so short that it's length becomes an oscillating waveform. Try making a simple [delwrite~ delayname] and a [vd~ delayname]. Now make a feedback loop by connecting the [vd~ delayname] back into the [delwrite~ delayname], and multiply this by a number less than 1. Something between .9 and .99 will give you a good ringing sound. The output of the [vd~ delayname] also gets sent out to the [adc~] for you to hear.
Divide the samplerate by the frequency you want the comb filter to resonate at, then divide by 1000 to get the delay length to send to the [vd~ delayname]. It would be good to put your [delwrite~] and [vd~] objects in a subpatch with a [block~ 1] object, which sets the blocksize to 1 and allows for the shortest possible delay times [which in turn gives you the highest possible resonant frequencies].
To make a resonant series, make multiple instances of this [as abstractions, don't forget to use $0 in the "delayname"!], and send the base frequency to the first comb filter abstraction, and multiplications or divisions of that to subsequent "harmonic" subpatches. Integers [2,3,4...] will produce clean harmonics, while other numbers [.98, 1.34, 2.22...] will be detuned to various degrees, resulting in an acoustic "beating" phenomenon as waveforms amplify and cancel each other out.
The same audio input is sent to all the comb filters. Sharp, percussive sounds will "ring" the filters, giving you a plucked-string kind of sound. Continuous sounds give something like a guitar or sitar type of drone. Try changing the multipliers of the "harmonic" filters for different drone or tonal effects.
All in all, I find it is much better for people to understand the principles of how these things work, so building your own will be great practice! Google for "karplus-strong" for more technical/mathmatical info.
Good luck, derek