Cybernetic music with SuperCollider

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Hi there,

here is a contri with a favourite Cross FM patch of mine - this is dumb simple, yet it can keep me busy for hours riding the sliders in tiny steps and wonder at the impredictable results I’m getting: a perfect chaos theory primer in sound


// simple cross-FM, inspired by Joker Nies
(
Ndef(\xfm, { arg freqA = 32, freqB = 9, modAtoB=540, modBtoA=240;
	var fbIn = LocalIn.ar(2);
	var sigs = SinOsc.ar([freqA, freqB] + (fbIn.reverse * [modBtoA, modAtoB]));
	LocalOut.ar(sigs);
	sigs * 0.5;
}).play;

Spec.add(\freqA, [1, 10000, \exp]);
Spec.add(\freqB, [1, 10000, \exp]);
Spec.add(\modBtoA, [0, 1000, 5]);
Spec.add(\modAtoB, [0, 1000, 5]);

Ndef(\xfm).gui;
);

// some chaotic presets that display roughness, instabilities, or
Ndef('xfm').set('freqA', 9.0, 'freqB', 40.0, 'modAtoB', 205,  'modBtoA', 243.64);
Ndef('xfm').set('freqA', 5, 'freqB', 40.0, 'modAtoB', 90.0, 'modBtoA', 155); // try riding the modBtoA slider just slightly with the arrow buttons > find completely different states; hysteresis when returning. Pitch may move in reverse.
Ndef('xfm').set('freqA', 14, 'freqB', 6.69, 'modAtoB', 151, 'modBtoA', 402);

Ndef('xfm').set('freqA', 5, 'freqB', 40.0, 'modAtoB', 90.0, 'modBtoA', 204); // chaotic oscillation between several states

// settling after a short while - press 'send' on the GUI to restart process deterministically
Ndef('xfm').set('freqA', 5.0, 'freqB', 6.36, 'modAtoB', 342.65, 'modBtoA', 448.48);
Ndef('xfm').set('freqA', 223.46, 'freqB', 6.69, 'modAtoB', 70.57, 'modBtoA', 726.15);
Ndef('xfm').set('freqA', 18, 'freqB', 40.0, 'modAtoB', 90.0, 'modBtoA', 172.0);

// ideas to extend:
// - add sample-and-hold
// - more than 2 operators in circle feedback topology

Quite certainly, the delay introduced by LocalIn / LocalOut does have an effect on the sound; one can test different configurations with different blockSizes, and the above feedback patch behaves slightly differently

s.options.blockSize_(64 * 4);
s.options.blockSize_(64); // default
s.options.blockSize_(2);
s.options.blockSize_(1);
s.reboot;

but the question is, different effects in relation to what? The lower we go with the blocksize, the more we approximate the analog world, but it’s clear that in relation to electrons’ flow, 1 sample is wayyy long, and we’ll never get really close to the analog with our digital systems.
So, tuning to the sonic result will usually be all that’s needed.

Bests,
Hannes

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