Soft A VCA

[biminiroad]

Soft A VCA

This VCA models the characteristics of soft clipping distortion present in analog VCAs. It isn’t a model of any particular type of VCA, but it does sound very warm.

Note: The “A” just refers to the fact that there will be more soft clip VCAs like this one that tweak the transform formula.

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I/O

Input	Signal Range	Notes
	-1 to 1	Audio input
	0 to 1	Modulation input

Output	Signal Range	Notes
	-1 to 1	Audio output

Controls

Knob	Function	Notes
	Overdrive	Amount of soft clipping distortion
	Feedback	Amount of internal feedback
	Level	Maximum modulation input level

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Version History

Revision	File	Date	Notes
1.0	Soft A VCA.audulus (20.8 KB)	5/30/18	Initial upload

Demos

Revision	File	Date	Notes
1.0	Soft A VCA Bass Comparison Demo.audulus (233.7 KB)	5/30/18	A demo to compare the sound of the VCA vs. a digital linear clean VCA
1.0	Soft A VCA Filter Demo.audulus (367.6 KB)	5/30/18	A demo using the K35 LPF in a more typical subtractive synth layout

[robertsyrett]

Why does "((x>=1)*0.5+(x<1)*(x>0)*(-0.5*x^2+x)+(x<0)*(x>-1)*(0.5*x^2+x)+(x<=-1)*-0.5)*2" sound so much like a filter?

[biminiroad]

Well if it’s cranked up, it’s adding harmonics, and as you back it off, it is subtracting them? Is that maybe what you’re hearing?

Quick hint - use backticks “``” between expressions like that to get pretty formatting like this:

((x>=1)0.5+(x<1)(x>0)(-0.5x^2+x)+(x<0)(x>-1)(0.5x^2+x)+(x<=-1)-0.5)*2

or the double dollar signs for even prettier versions

((x>=1)0.5+(x<1)(x>0)(-0.5x^2+x)+(x<0)(x>-1)(0.5x^2+x)+(x<=-1)-0.5)*2

[robertsyrett]

@biminiroad

or the double dollar signs for even prettier versions

((x>=1)0.5+(x<1)(x>0)(−0.5x2+x)+(x<0)(x>−1)(0.5x2+x)+(x<=−1)−0.5)∗2

Wait, how does the double dollar signs work?

[futureaztec]

Another beautiful tool. Stoked on the sound of this @biminiroad. I also like how you set up the sequencers with 1 running at 1/32.

[biminiroad]

Thanks! Glad you dig The underlying distortion is pretty cpu efficient too.

@futureaztec

I also like how you set up the sequencers with 1 running at 1/32.

Yeah! That’s a technique I like to use to give a little motion to the random sequencer. Basically the random sequencer is a sort of random arpeggiator and the second sequencer clocked at 1/32 you can think of as the note being played.