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BP filter with harmonics adjustment

July 9, 2013 | 7:50 am

Hi.
At this moment i’m thinking on how to make a filter with harmonics frequencies control. It would be really nice if you give me any assistance or solution with that.

For example: I want to make a sawtooth wave at 100 Hz from white noise => i need to filter 31 harmonics with gain ratio = 1/n. Where is n – harmonics number.


July 9, 2013 | 11:38 am

What’s the sound you’re going for? And how efficient does it need to be? Do you need to be able to sweep it? If you’re not sweeping the filters, you could just use fffb~. (Fast Fixed Filter Bank)

If you needed to sweep the filters, you could make this as a poly~ patch pretty quickly. You might also experiment with using comb~ as a pre-filter to this. Running 31 filters may not be the most practical way to generate a sawtooth, though.

A more efficient way would be to use some combination of comb-filtering and post-filtering. Comb-filtering will provide harmonics, and then use a high-shelf filter to tailor the harmonics as needed. You also may have better luck if you use pink noise as input source. This obviously doesn’t have the nice individual controls for Q, etc. and will have a different sound, but still might be useful.


July 10, 2013 | 1:48 am

Thanks for answer.

I have a crazy idea to make a subtructive-additive synth. =)
I’did not thought about sweeping, but i think there is no need in it to control frequencies via MIDI notes. Am i right?

So you mean that even fffb~ may be controlled polyphonic via midi with fixed harmonics ratio?
I understand that 31 filters is not most practical, but to make first steps, i want to make a simple algorithm first, than add more harmonics (64).

Oh, i also forgot to place a patch of what i am doing now which explains my thoughts (i want to make something like Chimera VST. Maybe it’ll give more light.
Also it shows that for now i’m using filtergraph~ + cascade~ to make textures from noise.


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