--- /dev/null
+
+/* A simple "chimes" patch, using a bank of resonz filters (cf. Steiglitz, DSP
+ Primer, pp. 89f.). */
+
+declare name "chimes -- chimes synth using a bank of resonz filters";
+declare author "Albert Graef";
+declare version "2.0";
+
+import("music.lib");
+
+/* Control variables: */
+
+// master volume, pan
+vol = hslider("vol", 0.5, 0, 10, 0.01); // %
+pan = hslider("pan", 0.5, 0, 1, 0.01); // %
+
+// excitator and resonator parameters
+
+// excitator decay time [sec]
+xdecay = nentry("decay", 0.01, 0, 1, 0.001);
+
+// resonator #0
+hrm0 = nentry("harmonic0", 1, 0, 50, 0.001); // harmonic
+amp0 = nentry("amplitude0", 0.167, 0, 1, 0.001); // amplitude
+decay0 = nentry("decay0", 3.693, 0, 10, 0.001); // decay time
+rq0 = nentry("rq0", 0.002, 0, 1, 0.0001); // filter 1/Q
+// resonator #1
+hrm1 = nentry("harmonic1", 3.007, 0, 50, 0.001); // harmonic
+amp1 = nentry("amplitude1", 0.083, 0, 1, 0.001); // amplitude
+decay1 = nentry("decay1", 2.248, 0, 10, 0.001); // decay time
+rq1 = nentry("rq1", 0.002, 0, 1, 0.0001); // filter 1/Q
+// resonator #2
+hrm2 = nentry("harmonic2", 4.968, 0, 50, 0.001); // harmonic
+amp2 = nentry("amplitude2", 0.087, 0, 1, 0.001); // amplitude
+decay2 = nentry("decay2", 2.828, 0, 10, 0.001); // decay time
+rq2 = nentry("rq2", 0.002, 0, 1, 0.0001); // filter 1/Q
+// resonator #3
+hrm3 = nentry("harmonic3", 8.994, 0, 50, 0.001); // harmonic
+amp3 = nentry("amplitude3", 0.053, 0, 1, 0.001); // amplitude
+decay3 = nentry("decay3", 3.364, 0, 10, 0.001); // decay time
+rq3 = nentry("rq3", 0.002, 0, 1, 0.0001); // filter 1/Q
+// resonator #4
+hrm4 = nentry("harmonic4", 12.006, 0, 50, 0.001); // harmonic
+amp4 = nentry("amplitude4", 0.053, 0, 1, 0.001); // amplitude
+decay4 = nentry("decay4", 2.488, 0, 10, 0.001); // decay time
+rq4 = nentry("rq4", 0.002, 0, 1, 0.0001); // filter 1/Q
+
+// frequency, gain, gate
+freq = nentry("freq", 440, 20, 20000, 1); // Hz
+gain = nentry("gain", 1, 0, 10, 0.01); // %
+gate = button("gate"); // 0/1
+
+/* Definition of the resonz filter. This is basically a biquad filter with
+ pairs of poles near the desired resonance frequency and zeroes at -1 and
+ +1. See Steiglitz for details. */
+
+resonz(R,freq) = f : (+ ~ g)
+with {
+ f(x) = a*(x-x'); // feedforward function (two zeros)
+ g(y) = 2*R*c*y - R*R*y'; // feedback function (two poles)
+ w = 2*PI*freq/SR; // freq in rad per sample period
+ c = 2*R/(1+R*R)*cos(w); // cosine of pole angle
+ s = sqrt (1-c*c); // sine of pole angle
+ a = (1-R*R)*s; // factor to normalize resonance
+};
+
+/* The excitator, a short burst of noise. */
+
+excitator(t) = t : hgroup("1-excitator", adsr(0, xdecay, 0, 0) : *(noise));
+
+/* Bank of 5 resonators. */
+
+resonator(f,t,i,hrm,amp,decay,rq)
+ = (f,t,_) : hgroup("2-resonator-%i", g)
+with {
+ g(f,t) = resonz(R,h)*(amp*b*env)
+ with {
+ h = hrm*f; // harmonic
+ B = rq*f/SR; // bandwidth, as fraction of sample rate
+ R = 1-PI*B; // resonance (pole radius)
+ b = 1/(2*B); // boost factor = Nyquist/bandwidth
+ env = adsr(0, decay, 0, 0, t); // envelop
+ };
+};
+
+resonators(f,t) = resonator(f,t,0,hrm0,amp0,decay0,rq0)
+ + resonator(f,t,1,hrm1,amp1,decay1,rq1)
+ + resonator(f,t,2,hrm2,amp2,decay2,rq2)
+ + resonator(f,t,3,hrm3,amp3,decay3,rq3)
+ + resonator(f,t,4,hrm4,amp4,decay4,rq4);
+
+/* The synth. */
+
+process = excitator(gate)*gain <: resonators(freq, gate)
+ : vgroup("3-master", *(vol) : panner(pan));