chebyshev ripple db (<0.0)
qfactor (resonator) (>0.0)
frequency Alpha Low Alpha Up or

samplerate: Hz
Lower corner Hz Midi note (69=A440)
Upper corner Hz Midi note (69=A440)
more matched z-transform (better off, check frequency response)
prewarp (better on)
Signal bits (including sign): -1 bit saturation save
brutal shift, this will remove shifts up to 4 positions by changing the factor, hence reducing accuracy by maximum 4 bits but more efficient calculation

//Low pass butterworth filter order=2 alpha1=0.01 class FilterBuLp2 { public: FilterBuLp2() { v[0]=0.0; v[1]=0.0; v[2]=0.0; } private: float v[3]; public: float step(float x) //class II { v[0] = v[1]; v[1] = v[2]; v[2] = (9.446918438401618072e-4 * x) + (-0.91497583480143362955 * v[0]) + (1.91119706742607298189 * v[1]); return (v[0] + v[2]) +2 * v[1]; } };