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TR-808/909 Drum Synthesis DSP Refinement #49

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20 changes: 10 additions & 10 deletions src/logic/DrumMachine.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -104,19 +104,19 @@ export class DrumMachine {

if (this.currentKit === '808') {
switch (drum) {
case 'kick': kit808.kick.trigger(time, p.pitch, p.decay); break
case 'snare': kit808.snare.trigger(time, p.pitch, p.decay); break
case 'hihat': kit808.hihat.trigger(time, false, p.pitch, p.decay); break
case 'hihatOpen': kit808.hihatOpen.trigger(time, true, p.pitch, p.decay); break
case 'clap': kit808.clap.trigger(time, p.pitch, p.decay); break
case 'kick': kit808.kick.trigger(time, p.pitch, p.decay, velocity); break
case 'snare': kit808.snare.trigger(time, p.pitch, p.decay, velocity); break
case 'hihat': kit808.hihat.trigger(time, false, p.pitch, p.decay, velocity); break
case 'hihatOpen': kit808.hihatOpen.trigger(time, true, p.pitch, p.decay, velocity); break
case 'clap': kit808.clap.trigger(time, p.pitch, p.decay, velocity); break
}
} else {
switch (drum) {
case 'kick': kit909.kick.trigger(time, p.pitch, p.decay); break
case 'snare': kit909.snare.trigger(time, p.pitch, p.decay); break
case 'hihat': kit909.hihat.trigger(time, false, p.pitch, p.decay); break
case 'hihatOpen': kit909.hihatOpen.trigger(time, true, p.pitch, p.decay); break
case 'clap': kit909.clap.trigger(time, p.pitch, p.decay); break
case 'kick': kit909.kick.trigger(time, p.pitch, p.decay, velocity); break
case 'snare': kit909.snare.trigger(time, p.pitch, p.decay, velocity); break
case 'hihat': kit909.hihat.trigger(time, false, p.pitch, p.decay, velocity); break
case 'hihatOpen': kit909.hihatOpen.trigger(time, true, p.pitch, p.decay, velocity); break
case 'clap': kit909.clap.trigger(time, p.pitch, p.decay, velocity); break
}
}
}
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8 changes: 4 additions & 4 deletions src/logic/drums/TR808Clap.ts
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Expand Up @@ -10,7 +10,7 @@ export class TR808Clap {
for (let i = 0; i < data.length; i++) data[i] = Math.random() * 2 - 1;
}

trigger(time: number, pitch: number, decay: number) {
trigger(time: number, pitch: number, decay: number, velocity: number = 0.8) {
const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
const filterVariance = 1 + (Math.random() * 0.04 - 0.02); // +/- 2% filter
const bpf = new Tone.Filter((1000 + pitch * 1000) * filterVariance, "bandpass");
Expand All @@ -26,16 +26,16 @@ export class TR808Clap {

for (let i = 0; i < snapCount; i++) {
const snapTime = time + i * snapInterval;
gain.gain.setValueAtTime(1, snapTime);
gain.gain.exponentialRampToValueAtTime(0.1, snapTime + snapInterval * 0.8);
gain.gain.setValueAtTime(velocity, snapTime);
gain.gain.exponentialRampToValueAtTime(0.1 * velocity, snapTime + snapInterval * 0.8);
}

// Final decay
const finalDecayStart = time + snapCount * snapInterval;
const decayTimeBase = 0.1 + decay * 0.5;
const decayTime = decayTimeBase * (1 + (Math.random() * 0.04 - 0.02)); // +/- 2% decay

gain.gain.setValueAtTime(1, finalDecayStart);
gain.gain.setValueAtTime(velocity, finalDecayStart);
gain.gain.exponentialRampToValueAtTime(0.001, finalDecayStart + decayTime);

noiseSrc.start(time).stop(finalDecayStart + decayTime);
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6 changes: 3 additions & 3 deletions src/logic/drums/TR808HiHat.ts
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Expand Up @@ -5,7 +5,7 @@ export class TR808HiHat {

constructor(private destination: Tone.ToneAudioNode) { }

trigger(time: number, isOpen: boolean, pitch: number, decay: number) {
trigger(time: number, isOpen: boolean, pitch: number, decay: number, velocity: number = 0.8) {
// Create nodes
const mixGain = new Tone.Gain(0.15);
const bpf1 = new Tone.Filter(3440, "bandpass");
Expand Down Expand Up @@ -47,8 +47,8 @@ export class TR808HiHat {
const decayBase = isOpen ? (0.3 + decay * 0.2) : (0.04 + decay * 0.02);
const decayTime = decayBase * (1 + (Math.random() * 0.04 - 0.02)); // +/- 2% decay

// VCA Envelope
envGain.gain.setValueAtTime(1, time);
// VCA Envelope with velocity scaling
envGain.gain.setValueAtTime(velocity, time);
envGain.gain.exponentialRampToValueAtTime(0.001, time + decayTime);

// Scheduling
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6 changes: 3 additions & 3 deletions src/logic/drums/TR808Kick.ts
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Expand Up @@ -3,7 +3,7 @@ import * as Tone from 'tone'
export class TR808Kick {
constructor(private destination: Tone.ToneAudioNode) { }

trigger(time: number, pitch: number, decay: number) {
trigger(time: number, pitch: number, decay: number, velocity: number = 0.8) {
// pitch: 0.5 -> 52.5Hz, maps to 45-60Hz range
const tune = 45 + pitch * 15;
// decay: 0.5 -> 1.7s, maps to 0.4-3.0s range
Expand All @@ -30,8 +30,8 @@ export class TR808Kick {
osc.frequency.setValueAtTime(startFreq, time);
osc.frequency.exponentialRampToValueAtTime(endFreq, time + pitchDropTime);

// VCA Amp Envelope: Instant attack, adjustable exponential decay
masterGain.gain.setValueAtTime(1, time);
// VCA Amp Envelope: Instant attack, adjustable exponential decay, scaled by velocity
masterGain.gain.setValueAtTime(velocity, time);
masterGain.gain.exponentialRampToValueAtTime(0.001, time + finalDecay);

osc.start(time).stop(time + finalDecay);
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13 changes: 7 additions & 6 deletions src/logic/drums/TR808Snare.ts
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Expand Up @@ -13,7 +13,7 @@ export class TR808Snare {
}
}

trigger(time: number, pitch: number, snappy: number) {
trigger(time: number, pitch: number, snappy: number, velocity: number = 0.8) {
// pitch maps to tone balance here (balance between low and high modes)
const toneBalance = pitch;

Expand All @@ -24,9 +24,9 @@ export class TR808Snare {
const snappyDecay = snappyDecayBase * (1 + (Math.random() * 0.04 - 0.02));
const filterVariance = 1 + (Math.random() * 0.04 - 0.02);

// 808 Membrane modes: fixed at ~238Hz and ~476Hz according to research
const oscLow = new Tone.Oscillator(238 + drift, "sine");
const oscHigh = new Tone.Oscillator(476 + drift, "sine");
// 808 Membrane modes: 180Hz and 330Hz as per research average
const oscLow = new Tone.Oscillator(180 + drift, "sine");
const oscHigh = new Tone.Oscillator(330 + drift, "sine");
oscLow.phase = Math.random() * 360;
oscHigh.phase = Math.random() * 360;

Expand All @@ -40,7 +40,8 @@ export class TR808Snare {
gainHigh.connect(masterTonalGain);
masterTonalGain.connect(this.destination);

masterTonalGain.gain.setValueAtTime(1, time);
// Apply velocity once at master gain level
masterTonalGain.gain.setValueAtTime(velocity, time);
// Tonal body decay is short (~200ms)
masterTonalGain.gain.exponentialRampToValueAtTime(0.001, time + vcaDecay);

Expand All @@ -54,7 +55,7 @@ export class TR808Snare {
noiseFilter.connect(snappyGain);
snappyGain.connect(this.destination);

snappyGain.gain.setValueAtTime(0.8, time);
snappyGain.gain.setValueAtTime(0.8 * velocity, time);
snappyGain.gain.exponentialRampToValueAtTime(0.001, time + snappyDecay);

oscLow.start(time).stop(time + vcaDecay);
Expand Down
29 changes: 17 additions & 12 deletions src/logic/drums/TR909Kick.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -13,34 +13,38 @@ export class TR909Kick {
}
}

trigger(time: number, pitch: number, decay: number) {
// pitch: 0.5 -> 50Hz, maps to 45-55Hz
trigger(time: number, pitch: number, decay: number, velocity: number = 0.8) {
// Research: Tune controls the pitch envelope decay time (0.05s - 0.15s)
const pitchEnvDecay = 0.05 + pitch * 0.1;
// Final frequency is relatively stable for 909 (45Hz - 55Hz)
const tune = 45 + pitch * 10;
// decay: 0.5 -> 0.45s, maps to 0.3-0.6s
// Amp decay: 0.5 -> 0.45s, maps to 0.3-0.6s
const decayTime = 0.3 + decay * 0.3;

// Micro-randomization
const drift = (Math.random() * 2 - 1) * 0.5; // +/- 0.5Hz drift
const vcaDecay = decayTime * (1 + (Math.random() * 0.04 - 0.02)); // +/- 2% decay
const filterVariance = 1 + (Math.random() * 0.04 - 0.02); // +/- 2% filter

// 909 Kick Body: Triangle Oscillator
const bodyOsc = new Tone.Oscillator(tune * 4.7 + drift, "triangle");
// 909 Kick Body: Triangle Oscillator + Smoothing LowPass Filter
const bodyOsc = new Tone.Oscillator(0, "triangle"); // Freq set via envelope
bodyOsc.phase = Math.random() * 360;
const bodyFilter = new Tone.Filter(1000 * filterVariance, "lowpass");
const bodyGain = new Tone.Gain(0);

bodyOsc.connect(bodyGain);
bodyOsc.connect(bodyFilter);
bodyFilter.connect(bodyGain);
bodyGain.connect(this.destination);

// Aggressive Pitch Envelope: Start at Tune * 4.7 (~235Hz) and drop over 100ms
// Aggressive Pitch Envelope: Start at Tune * 4.7 and drop over variable duration (from Tune knob)
const startFreq = tune * 4.7 + drift;
const endFreq = tune + drift;

bodyOsc.frequency.setValueAtTime(startFreq, time);
bodyOsc.frequency.exponentialRampToValueAtTime(endFreq, time + 0.1);
bodyOsc.frequency.exponentialRampToValueAtTime(endFreq, time + pitchEnvDecay);

// VCA Envelope
bodyGain.gain.setValueAtTime(1, time);
// VCA Envelope with velocity scaling
bodyGain.gain.setValueAtTime(velocity, time);
bodyGain.gain.exponentialRampToValueAtTime(0.001, time + vcaDecay);

// Click Layer (Noise)
Expand All @@ -52,16 +56,17 @@ export class TR909Kick {
noiseFilter.connect(noiseGain);
noiseGain.connect(this.destination);

// Ultra short envelope (10-20ms) for the click
// Ultra short envelope (10-20ms) for the click, also velocity scaled
const clickDecay = 0.02 * (1 + (Math.random() * 0.04 - 0.02));
noiseGain.gain.setValueAtTime(0.7, time);
noiseGain.gain.setValueAtTime(0.7 * velocity, time);
noiseGain.gain.exponentialRampToValueAtTime(0.001, time + clickDecay);

bodyOsc.start(time).stop(time + vcaDecay);
noiseSrc.start(time).stop(time + clickDecay);

bodyOsc.onstop = () => {
bodyOsc.dispose();
bodyFilter.dispose();
bodyGain.dispose();
};
noiseSrc.onended = () => {
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15 changes: 10 additions & 5 deletions src/logic/drums/TR909Snare.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ export class TR909Snare {
}
}

trigger(time: number, pitch: number, snappy: number) {
trigger(time: number, pitch: number, snappy: number, velocity: number = 0.8) {
// 909 Snare Body: 2 triangle oscillators fixed at ~160Hz and ~220Hz
const freq1 = 160;
const freq2 = 220;
Expand All @@ -30,10 +30,14 @@ export class TR909Snare {
const osc2 = new Tone.Oscillator(freq2 * 2 + drift, "triangle");
osc1.phase = Math.random() * 360;
osc2.phase = Math.random() * 360;

// Slight saturation/waveshaping for tonal body
const shaper = new Tone.WaveShaper((x) => Math.tanh(x * 1.5));
const tonalGain = new Tone.Gain(0);

osc1.connect(tonalGain);
osc2.connect(tonalGain);
osc1.connect(shaper);
osc2.connect(shaper);
shaper.connect(tonalGain);
tonalGain.connect(this.destination);

// 2x Pitch Sweep over 30ms (research says ~30ms for 909 Snare)
Expand All @@ -43,7 +47,7 @@ export class TR909Snare {
osc2.frequency.setValueAtTime(freq2 * 2 + drift, time);
osc2.frequency.exponentialRampToValueAtTime(freq2 + drift, time + sweepTime);

tonalGain.gain.setValueAtTime(1, time);
tonalGain.gain.setValueAtTime(velocity, time);
tonalGain.gain.exponentialRampToValueAtTime(0.001, time + vcaDecay);

// Snappy Layer
Expand All @@ -58,7 +62,7 @@ export class TR909Snare {
lpf.connect(noiseGain);
noiseGain.connect(this.destination);

noiseGain.gain.setValueAtTime(0.7, time);
noiseGain.gain.setValueAtTime(0.7 * velocity, time);
noiseGain.gain.exponentialRampToValueAtTime(0.001, time + snappyDecay);

osc1.start(time).stop(time + vcaDecay);
Expand All @@ -68,6 +72,7 @@ export class TR909Snare {
osc1.onstop = () => {
osc1.dispose();
osc2.dispose();
shaper.dispose();
tonalGain.dispose();
};
noiseSrc.onended = () => {
Expand Down
6 changes: 5 additions & 1 deletion src/store/instrumentStore.ts
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Expand Up @@ -32,11 +32,15 @@ interface DrumState {
}

export const useDrumStore = create<DrumState>((set) => ({
// Kick: 4-on-the-floor
kick: { steps: 16, pulses: 4, rotate: 0, decay: 0.5, pitch: 0.5 },
// Snare/Clap: Backbeat (2 and 4), rotated by 4 steps (16/2 rot 4)
snare: { steps: 16, pulses: 2, rotate: 4, decay: 0.5, pitch: 0.5 },
clap: { steps: 16, pulses: 2, rotate: 4, decay: 0.5, pitch: 0.5 },
// Hi-hat: 16th note pattern
hihat: { steps: 16, pulses: 12, rotate: 0, decay: 0.5, pitch: 0.5 },
// Open Hi-hat: Off-beat (rotated by 2)
hihatOpen: { steps: 16, pulses: 2, rotate: 2, decay: 0.5, pitch: 0.5 },
clap: { steps: 16, pulses: 0, rotate: 0, decay: 0.5, pitch: 0.5 },
kit: '909',
setParams: (drum, params) => set((state) => ({
[drum]: { ...state[drum], ...params }
Expand Down