Nov. 2019 – Brassification
One of the recent discoveries of accoustic scientists was the realization that “brassiness” in part comes from the viscosity of air: a really loud sound wave (for example, as found inside a trombone being played loud) actually travels faster than a soft one. For brass, the effect is that the waveshape distorts on loud notes, so that the leading edges push ahead while the trailing edges return to their normal position: surprisingly the peaks travel faster than troughs!
If you are using a sawtooth-based waveshaper you can get this effect merely by mixing a bit of the post-VCA final output in with the sawtooth wave going into the waveshaper. This works because a waveshaper that uses a sawtooth input can be considered to be responding to phase rather than just amplitude.) You are not trying to get feedback effects or an oscillation, just a level-dependent impact on the tone.)
So the leading edge of a loud output will cause the phase to be sightly ahead, and that will give a version of the brass effect. (Of course, it may not sound brassy at all, depending on what waveshape you are using, filter settings and so on.) (This may also cause some temporary pitch effect between soft and loud parts of the envelope too: another brass distinctive feature.)
Now to improve this, you would also trim the amount of modulation by the KCV: the speed-up in nature is not so dependent on the frequency: the speed-up will cause more distortion on higher notes.
You can do this on any sawthooth-based waveshaper, but the effect may be marginal for waveshapers like ProPulse or Blip! that produce pulse waves. It should be more useful for waveshapers that produce continuous outputs, such as Shell and Rasp.
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