Rudimentary Convolver

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E8_Heterotic
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Rudimentary Convolver

Post by E8_Heterotic » Wed Jan 09, 2019 4:32 pm

This is a very complicated module which uses a series of band pass filters to isolate the harmonics of 2 sounds. Each harmonic is then separately multiplied with the corresponding harmonic of the other sound by using amplitude modulation (technically ring modulation). The result is, essentially, the convolution of the 2 incoming signals. It's a crude approximation to such a convolution, but it does actually produce some expected results, such as two square waves producing an approximate triangle wave. The controllers allow you to pick the frequency bands that pass through the filters, as well as the wave forms, volume, and duty cycle of the two analog generators. You can also control the final output volume.

If you want to use something other than 2 analog generators, just open up the convolver in edit mode and insert some other signal into one of the two outer amplifiers instead of the analog generators. Make sure the other signal is triggered by the MultiSynth instead of the analog generator you're bypassing.

Note: A real convolution would be very similar, but the two signals would be perfectly decomposed into constituent sine waves (probably using a FFT) and then the corresponding waves would be multiplied.

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Keres
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Re: Rudimentary Convolver

Post by Keres » Thu Jan 17, 2019 9:18 am

been eyeing this thread for a week or 2 now... very interesting. guess you could make a .sunsynth that convolves the left against the right. you could use a pair to get stereo. here is something like that, spare that it uses the sound2ctrl to just amplitude modulate the signals. CPU is always an issue.
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E8_Heterotic
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Re: Rudimentary Convolver

Post by E8_Heterotic » Sun Jan 20, 2019 9:28 am

Keres wrote:
Thu Jan 17, 2019 9:18 am
been eyeing this thread for a week or 2 now... very interesting. guess you could make a .sunsynth that convolves the left against the right. you could use a pair to get stereo. here is something like that, spare that it uses the sound2ctrl to just amplitude modulate the signals. CPU is always an issue.
I suppose I could modify it so that it takes a single signal and splits it into left and right channels, convolving them. That way you can plug anything you want into it without opening it up, but you would need one input to be panned hard left, the other hard right and then sum them together in an amplifier.

That's a little more efficient than what I have now.

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Keres
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Re: Rudimentary Convolver

Post by Keres » Tue Jan 22, 2019 11:14 am

yeah that was the idea. to be honest, i think that many tracks can get away with simple mixers that sound like convolvers but are really just amplitude or filtering fades. proper mixing and fading can produce the same sounds. I think if there were going to be a proper FFT spectral morphing in sunvox wouldn't it make more sense to have it as an effect in the sampler? i think of an old macintosh music app with "patch morphing" where you selected 2 samples and it mixed them by % into a 3rd new sample. for CPU, samplers can be your friend. There is an app that i played with called analog box... or Abox2.4 by andy j. turner. you can send things into the FFT domain then say... make a pitch shifter or verb or something then transform it out. you should check that out... that does it real-time sortov. thing is that the quality is not too high and it is pretty much limited to windows. (hand coded assembler).

cheers!

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