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declare name "karplusplus -- Karplus-Strong + Fuzz";
declare author "Yann Orlarey, Albert Graef";
declare version "1.0";
import("music.lib");
// control variables
// master volume and pan
vol = hslider("vol", 0.3, 0, 10, 0.01); // %
pan = hslider("pan", 0.5, 0, 1, 0.01); // %
// excitator and resonator parameters
size = hslider("samples", 512, 1, 1024, 1); // #samples
dtime = hslider("decay time", 4, 0, 10, 0.01);// -60db decay time
// fuzz parameters
drive = hslider("drive", 0, 0, 50, 0.1); // overdrive factor
res = hslider("res", 0, 0, 20, 0.1); // filter resonance
tone = hslider("tone", 20, 1, 20, 0.1); // filter cutoff harmonic
level = hslider("level", 1, 0, 10, 0.01); // output gain (%)
// voice parameters
freq = nentry("freq", 440, 20, 20000, 1); // Hz
gain = nentry("gain", 1, 0, 10, 0.01); // %
gate = button("gate"); // 0/1
/* The excitator: */
upfront(x) = (x-x') > 0.0;
decay(n,x) = x - (x>0)/n;
release(n) = + ~ decay(n);
trigger(n) = upfront : release(n) : >(0.0) : +(leak);
leak = 1.0/65536.0; // avoid denormals on Pentium
excitator = trigger(size);
/* The resonator: */
average(x) = (x+x')/2;
att(d,t) = 1-1/pow(db2linear(60), d/(SR*t));
comb(d,a) = (+ : fdelay(4096, d-1.5)) ~ (average : *(1.0-a));
resonator(d) = comb(d,att(d,dtime));
/* DC blocker (see http://ccrma.stanford.edu/~jos/filters/DC_Blocker.html): */
dcblocker(x) = (x-x') : (+ ~ *(0.995));
// resonant lowpass
// This is a tweaked Butterworth filter by David Werner and Patrice Tarrabia,
// see http://www.musicdsp.org and http://www.experimentalscene.com for
// details.
// res = resonance in dB above DC gain
// freq = cutoff frequency
lowpass(res,freq) = f : (+ ~ g) : *(a)
with {
f(x) = a0*x+a1*x'+a2*x'';
g(y) = 0-b1*y-b2*y';
a = 1/db2linear(0.5*res);
c = 1.0/tan(PI*(freq/SR));
c2 = c*c;
r = 1/db2linear(2.0*res);
q = sqrt(2.0)*r;
a0 = 1.0/(1.0+(q*c)+(c2));
a1 = 2.0*a0;
a2 = a0;
b1 = 2.0*a0*(1.0-c2);
b2 = a0*(1.0-q*c+c2);
};
/* Fuzz effect. */
clip(x) = f*x+1-f with { f = abs(drive*x)<=1; };
fuzz(freq) = clip : lowpass(res,tone*freq) : *(level);
/* Karplus-Strong string synthesizer: */
process = vgroup("1-excitator", noise*gain : *(gate : excitator))
: vgroup("2-resonator", resonator(SR/freq)) : dcblocker
: vgroup("3-fuzz", fuzz(freq))
: vgroup("4-master", *(vol) : panner(pan));
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