Low Pass Circuits

@icedquinn One component that’s very simple to simulate is an RC low pass circuit.

out += c * (in - out)

0 < c < 1

Basically, for each sample, just make the output approximate the input by a small fraction. If the input is a step from one DC level to another, the output will follow a quadratic curve, which is what a resistor in series with the signal followed by a parallel capacitor will do. Chain several such RC circuits with buffer amps between and you go from 6 dB/oct to 12, etc.

@icedquinn If the output of the last step of the chain is fed back to the input, oscillation will occur and you get a resonant peak at the cutoff frequency set by c. Different amounts of feedback results in resonance levels.