How to make frequency modulation

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Joined: Tue Jun 09, 2015 12:24 pm

How to make frequency modulation

Post by Дож » Tue Jun 09, 2015 12:57 pm

Hi all there! I want to make frequency modulation without a FM module for experiments and for possibility to use any sound as a carrier, not only sine. I am trying to use this approach:

The Sound2Ctl controls pitch of the top Pitch Shifter Module.

My questions are:
1. Can this approach works at all? I don't exactly know sunvox specific of sound processing in the top Pitch Shifter, it seems the module needs very quick responsiveness and large intput buffer. (Visualization is not perfect on the screenshot…)
2. If it can, how should I setup the Sound2Ctl and bottom PitchShiffter? Obviously sampling rate must be maximized. I have troubles with the Gain and Smooth parameters.
3. How can I calculate a frequency of the final modulator signal? For example, the bottom generator plays C4, Pitch=-4, Pitch scale=50%, so final frequency is approximatly 261.63 Hz / (4 * 0.5) = 130.815 Hz. Is it correct?

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Location: Fort Lauderdale, Florida, USA

Re: How to make frequency modulation

Post by squidmissile » Thu Jun 11, 2015 5:38 am

I saw that no one respond yet and so i made an example tune (sound experiment 004, se004.sunvox (in zip attached)) to demonstrate how to achieve a basic setup for frequency modulation via phase modulation using SunVox's generators. The main points are really only 1.) having a sound source fed into a generator and 2.) turning up the phase modulation level. The rest is envelope work and fx.

Umm... Things I should probably mention are.... I used PM to create mostly everything except for the percussion (i got lazy, sorry). There are two kicks, one using the drumsynth and one using PM with relatively tuned generators.

For the bweep-y, pang-y sound I attempted to fake some kind of feedback using one generator (out of three) as a dedicated continuos drone fed into another one with phase modulation turned all the way up. Adjust the volume of the dedicated drone to adjust feedback. That's my best solution for achieving modulator feedback thus far... And most passable... So far. This is really just abusing additive synthesis to achieve feedback by turning a sine into.. More of a saw? I'm also automating amplifiers in place of using the AR(S) envelope in the generators for precise. line by line envelope control.

Anyways moving on, the chords/pad sound is setup in an additive synthesis style but i see it as an FM algorithm all the time so i decided to roll it anyhow. Each generator here is set to a different wave and tuned to taste via a multisynth (shoulda said that earlier i find it easier to make tuning/ratio adjustments via the multisynth instead of using the pitchshifter) to form a chord. A rather open one to add some bass to the tune.

I think that's about all i have to cover. And that's pretty much only covering question one. Showing how to get setup in a few different ways (anything can be a modulator in SunVox, go ham with fx (within reasonable limits of your machine, please)). For your third question i think you should have look at a few FM ratio articles... I play the tuning stuff by ear and feel.

Hope i was able to help. :)
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