sos.help.lhs

> import Sound.SC3 {- hsc3 -}

Same as TwoPole

> g_01 =
>   let theta = line KR (0.2 * pi) pi 5 RemoveSynth
>       rho = line KR 0.6 0.99 5 RemoveSynth
>       b1 = 2 * rho * cos theta
>       b2 = - (rho * rho)
>   in sos (lfSaw AR 200 0 * 0.1) 1 0 0 b1 b2

<http://www.earlevel.com/main/2011/01/02/biquad-formulas/>

> g_02 =
>   let fc = 100
>       sr = 48000
>       k = tan (pi * fc / sr)
>       q = 0.707
>       norm = 1 / (1 + k / q + k * k)
>       a0 = k * k * norm
>       a1 = 2 * a0
>       a2 = a0
>       b1 = 2 * (k * k - 1) * norm
>       b2 = (1 - k / q + k * k) * norm
>   in sos (whiteNoise 'a' AR * 0.2) a0 a1 a2 (- b1) (- b2)