1 2declare name "subtractive -- saw wave filtered with resonant lowpass"; 3declare author "Albert Graef"; 4declare version "1.0"; 5 6import("music.lib"); 7 8// control variables 9 10// master volume and pan 11vol = hslider("vol", 0.3, 0, 10, 0.01); // % 12pan = hslider("pan", 0.5, 0, 1, 0.01); // % 13 14// ADSR envelop 15attack = hslider("attack", 0.01, 0, 1, 0.001); // sec 16decay = hslider("decay", 0.3, 0, 1, 0.001); // sec 17sustain = hslider("sustain", 0.5, 0, 1, 0.01); // % 18release = hslider("release", 0.2, 0, 1, 0.001); // sec 19 20// filter parameters 21res = hslider("resonance (dB)", 3, 0, 20, 0.1); 22cutoff = hslider("cutoff (harmonic)", 6, 1, 20, 0.1); 23 24// voice parameters 25freq = nentry("freq", 440, 20, 20000, 1); // Hz 26gain = nentry("gain", 1, 0, 10, 0.01); // % 27gate = button("gate"); // 0/1 28 29// generic table-driven oscillator with phase modulation 30 31// n = the size of the table, must be a power of 2 32// f = the wave function, must be defined on the range [0,2*PI] 33// freq = the desired frequency in Hz 34// mod = the phase modulation signal, in radians 35 36tblosc(n,f,freq,mod) = (1-d)*rdtable(n,wave,i&(n-1)) + 37 d*rdtable(n,wave,(i+1)&(n-1)) 38with { 39 wave = time*(2.0*PI)/n : f; 40 phase = freq/SR : (+ : decimal) ~ _; 41 modphase = decimal(phase+mod/(2*PI))*n; 42 i = int(floor(modphase)); 43 d = decimal(modphase); 44}; 45 46// resonant lowpass 47 48// This is a tweaked Butterworth filter by David Werner and Patrice Tarrabia, 49// see http://www.musicdsp.org and http://www.experimentalscene.com for 50// details. 51 52// res = resonance in dB above DC gain 53// freq = cutoff frequency 54 55lowpass(res,freq) = f : (+ ~ g) : *(a) 56with { 57 f(x) = a0*x+a1*x'+a2*x''; 58 g(y) = 0-b1*y-b2*y'; 59 a = 1/db2linear(0.5*res); 60 61 c = 1.0/tan(PI*(freq/SR)); 62 c2 = c*c; 63 r = 1/db2linear(2.0*res); 64 q = sqrt(2.0)*r; 65 a0 = 1.0/(1.0+(q*c)+(c2)); 66 a1 = 2.0*a0; 67 a2 = a0; 68 b1 = 2.0*a0*(1.0-c2); 69 b2 = a0*(1.0-q*c+c2); 70}; 71 72// subtractive synth (saw wave passed through resonant lowpass) 73 74saw(x) = x/PI-1; 75 76smooth(c) = *(1-c) : +~*(c); 77 78process = tblosc(1<<16, saw, freq, 0) : ((env,freq,_) : filter) : 79 *(env * (gain/*:smooth(0.999)*/)) 80 : vgroup("3-master", *(vol) : panner(pan)) 81with { 82 env = gate : vgroup("1-adsr", adsr(attack, decay, sustain, release)); 83 filter(env,freq) 84 = vgroup("2-filter", lowpass(env*res, fmax(1/cutoff, env)*freq*cutoff)); 85}; 86