Key-follow for filters

[hlg]

Is there a builtin way to do this or has anyone written one?

[Christoph Hart]

You can use a Notenumber Modulator in the Frequency Chain of a filter for a quick estimate (it changes the modulation value depending on the note number, but it's not accurate). If you need correct values for each note frequency, you'll have to use a Voice Start Modulator in the Frequency chain and calculate the modulation value from the note number:

function onVoiceStart(voiceIndex)
{
	local nn = Message.getNoteNumber();	
	local freq = Engine.getFrequencyForMidiNoteNumber(nn);
	local ratio = (freq - 20.0) / 19980.0; // the modulation value (0 ... 1) for the linear frequency range
	
	return ratio;
}
function onVoiceStop(voiceIndex) {}
function onController() {}
function onControl(number, value) {}

Example patch:

A waveform generator with noise and self oscillating resonant filter (to demonstrate the correct frequency):

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[hlg]

Thank you! This should work fine.

[staiff]

i use filters on global FX slot, because of 2 synthesizer groups. So in the Fx section, impossible to activate a voice start modulator.

only usable if filter is in the waveform generator.

Is there a way to do the same thing with a container FX filter ?

thanks.

[Christoph Hart]

No because you don't have acces to the voices on container level (they are summed up by then).

[staiff]

yep !
i decided to change my filters. Because i had subtractive (with another subosc - 12 and noise osc) + FM. But in fact FM has no filters. so i put all waveforms in one synth group + filters and separate FM (2 sine osc) without filters.

for now i have keyfollow + polarity (because it also didn't work in FX filter mode)