R: [PD] resonant comb filter series

derek holzer derek at x-i.net
Wed Feb 16 17:29:05 CET 2005

OK, I'm back.

As far as I can figure, you made two boo-boos. The first was assuming 
that the output of [fiddle~] was in Hz, when it is in MIDI.

The second was too many objects in your low-blocksize subpatch. I can't 
explain why, but your subpatch was not operating at [block~ 1] for some 
reason. The only things that are necessary in that subpatch are the 
[vd~] and the [delwrite~]. Everything else should be left out.

I cleaned it up and have attached it here. The one last thing to note is 
that [fiddle~] will not give an "accurate" reading of the comb filter 
below around 138.5 Hz or MIDI note 49. As the delay gets longer, the 
resulting sound becomes less sinusoidal and closer to the noise which is 
driving the comb filter.


> Davide Morelli wrote:
>> Hi Derek,
>> Thank you for the explanation, Karplus-Strong gives charimng sounds.
>> But I can't make it resonate at the frequency I want.
>> I made a little testing patch trying to follow your guidelines as much 
>> as I
>> could.
>> What's wrong?
>> I googled a bit and I always found that deltime should be
>> deltime (sec) = 1/Freq(Hz)
>> example: to get a A440 sound I should
>> deltime (msec) = (1/440)*1000
>> why must we do
>> deltime (msec) = (samplerate~ / Freq(Hz)) / 1000
>> instead?
>> I can't get it...
>> (.. newbie)

derek holzer ::: http://www.umatic.nl
---Oblique Strategy # 36:
"Consult other sources
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