Tangle: a JavaScript library for reactive documents: "Below is a simplified digital adaptation of the analog state variable filter.
This topology is particularly useful for embedded audio processing, because Fc (cutoff frequency) and Q (resonance) are controlled by independent coefficients, kf and kq. (With most filters, the coefficients are functions of both parameters, which precludes pre-calculated lookup tables.)
The coefficients and transfer function are:
Some example frequency responses:
Fc = 2.33 KHz
Q = 0.83"
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