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Research-Based Drum Synthesis & DSP Refinement #42

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44 changes: 20 additions & 24 deletions src/logic/DrumMachine.ts
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Expand Up @@ -40,7 +40,8 @@ export class DrumMachine {

constructor() {
this.comp = new Tone.Compressor(-24, 4)
this.shaper = new Tone.WaveShaper(this.makeDistortionCurve(15))
this.shaper = new Tone.WaveShaper(this.makeDistortionCurve(20)) // Amount increased to 20 per research recommendation
this.shaper.oversample = '4x'
this.output = new Tone.Gain(1)
this.outputKick = new Tone.Gain(1)
this.outputSnare = new Tone.Gain(1)
Expand All @@ -50,14 +51,12 @@ export class DrumMachine {

this.comp.chain(this.shaper, this.output, Tone.Destination)

// Let's bypass compression for individual drum channels for now,
// to simplify routing and allow strict analog synth modeling.
// We'll route them directly to destination or output
this.outputKick.connect(Tone.Destination)
this.outputSnare.connect(Tone.Destination)
this.outputHihat.connect(Tone.Destination)
this.outputOpenHat.connect(Tone.Destination)
this.outputClap.connect(Tone.Destination)
// Route all individual drum outputs through the master compression/saturation chain for the "glue effect"
this.outputKick.connect(this.comp)
this.outputSnare.connect(this.comp)
this.outputHihat.connect(this.comp)
this.outputOpenHat.connect(this.comp)
this.outputClap.connect(this.comp)

this.kit808 = {
kick: new TR808Kick(this.outputKick),
Expand All @@ -81,6 +80,7 @@ export class DrumMachine {
const deg = Math.PI / 180
for (let i = 0; i < n_samples; ++i) {
let x = i * 2 / n_samples - 1
// Formula from research: (3 + k) * x * 20 * deg / (Math.PI + k * Math.abs(x))
curve[i] = (3 + k) * x * 20 * deg / (Math.PI + k * Math.abs(x))
}
return curve
Expand All @@ -101,26 +101,22 @@ 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.hihat.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.hihat.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 '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':
// Reuse hihat logic but specify it's open
// Note: technically TR909 uses samples for open hats, but we'll use our analog emulation for now
kit909.hihat.trigger(time, true, p.pitch, p.decay);
// However, we need to route it to the right output if possible. Our TR808HiHat
// currently has one destination baked in at constructor. To mix them separately,
// we will need an architectural tweak or just use the same channel. Let's just trigger it.
// Map to openHat output gain for visualization/mixing if needed
kit909.hihat.trigger(time, true, p.pitch, p.decay, velocity);
break
case 'clap': kit909.clap.trigger(time, p.pitch, p.decay); break
case 'clap': kit909.clap.trigger(time, p.pitch, p.decay, velocity); break
}
}
}
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21 changes: 13 additions & 8 deletions src/logic/drums/TR808Clap.ts
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Expand Up @@ -5,32 +5,37 @@ export class TR808Clap {

constructor(private destination: Tone.ToneAudioNode) {
const sampleRate = Tone.getContext().sampleRate;
this.noiseBuffer = Tone.getContext().createBuffer(1, sampleRate * 0.5, sampleRate);
this.noiseBuffer = (Tone.getContext().rawContext as AudioContext).createBuffer(1, sampleRate * 0.5, sampleRate);
const data = this.noiseBuffer.getChannelData(0);
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) {
// Micro-randomization (+/- 2%)
const filterVariance = 1 + (Math.random() * 0.04 - 0.02);
const decayVariance = 1 + (Math.random() * 0.04 - 0.02);
const snapVariance = 1 + (Math.random() * 0.04 - 0.02);

const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
const bpf = new Tone.Filter(1000 + pitch * 1000, "bandpass");
const bpf = new Tone.Filter((1000 + pitch * 1000) * filterVariance, "bandpass");
const gain = new Tone.Gain(0).connect(this.destination);

noiseSrc.connect(bpf);
bpf.connect(gain);

// Triple attack "snaps"
const snapCount = 3;
const snapInterval = 0.01;
const snapInterval = 0.01 * snapVariance;
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 decayTime = 0.1 + decay * 0.5;
gain.gain.setValueAtTime(1, finalDecayStart);
const decayTime = (0.1 + decay * 0.5) * decayVariance;
gain.gain.setValueAtTime(velocity, finalDecayStart);
gain.gain.exponentialRampToValueAtTime(0.001, finalDecayStart + decayTime);

noiseSrc.start(time).stop(finalDecayStart + decayTime);
Expand Down
16 changes: 13 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 All @@ -16,10 +16,15 @@ export class TR808HiHat {
// Pitch Multiplier (0.8x to 1.2x)
const pitchMultiplier = 0.8 + pitch * 0.4;

// Micro-randomization (+/- 2%)
const filterVariance = 1 + (Math.random() * 0.04 - 0.02);
const decayVariance = 1 + (Math.random() * 0.04 - 0.02);

// Create 6 Square Wave Oscillators (Schmitt Trigger Matrix)
const oscillators = this.frequencies.map(freq => {
const drift = (Math.random() - 0.5) * 4; // Analog drift
const osc = new Tone.Oscillator(freq * pitchMultiplier + drift, "square");
osc.phase = Math.random() * 360;
osc.connect(mixGain);
return osc;
});
Expand All @@ -37,11 +42,16 @@ export class TR808HiHat {
bpf1.Q.value = 1.5;
bpf2.Q.value = 1.5;

// Randomized filter cutoffs
bpf1.frequency.value = 3440 * filterVariance;
bpf2.frequency.value = 7100 * filterVariance;
hpf.frequency.value = 7000 * filterVariance;

// Decay: Closed Hat (40-60ms), Open Hat (300-500ms)
const decayTime = isOpen ? (0.3 + decay * 0.2) : (0.04 + decay * 0.02);
const decayTime = (isOpen ? (0.3 + decay * 0.2) : (0.04 + decay * 0.02)) * decayVariance;

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

// Scheduling
Expand Down
11 changes: 7 additions & 4 deletions src/logic/drums/TR808Kick.ts
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Expand Up @@ -3,11 +3,14 @@ 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;

// Micro-randomization on decay time (+/- 2%)
const decayVariance = 1 + (Math.random() * 0.04 - 0.02);
// decay: 0.5 -> 1.7s, maps to 0.4-3.0s range
const decayTime = 0.4 + decay * 2.6;
const decayTime = (0.4 + decay * 2.6) * decayVariance;

// 808 Kick Core: Bridged-T Network emulation
const osc = new Tone.Oscillator(tune, "sine");
Expand All @@ -17,7 +20,7 @@ export class TR808Kick {
osc.connect(masterGain);
masterGain.connect(this.destination);

// Micro-randomization: Pitch Drift (+/- 1-2 cents or ~0.5Hz)
// Micro-randomization: Pitch Drift (+/- 0.5Hz)
const drift = (Math.random() * 2 - 1) * 0.5;

// Pitch Envelope: Start high (Tune * 2.5) and drop quickly to simulate the membrane hit ('tonk')
Expand All @@ -29,7 +32,7 @@ export class TR808Kick {
osc.frequency.exponentialRampToValueAtTime(endFreq, time + pitchDropTime);

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

osc.start(time).stop(time + decayTime);
Expand Down
30 changes: 19 additions & 11 deletions src/logic/drums/TR808Snare.ts
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Expand Up @@ -6,20 +6,28 @@ export class TR808Snare {
constructor(private destination: Tone.ToneAudioNode) {
const sampleRate = Tone.getContext().sampleRate;
const bufferSize = sampleRate * 0.5; // 500ms
this.noiseBuffer = Tone.getContext().createBuffer(1, bufferSize, sampleRate);
this.noiseBuffer = (Tone.getContext().rawContext as AudioContext).createBuffer(1, bufferSize, sampleRate);
const data = this.noiseBuffer.getChannelData(0);
for (let i = 0; i < data.length; i++) {
data[i] = Math.random() * 2 - 1;
}
}

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;

// Micro-randomization (+/- 2%)
const filterVariance = 1 + (Math.random() * 0.04 - 0.02);
const decayVariance = 1 + (Math.random() * 0.04 - 0.02);
const drift = (Math.random() * 2 - 1) * 1; // +/- 1Hz

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

const gainLow = new Tone.Gain(1 - toneBalance);
const gainHigh = new Tone.Gain(toneBalance);
const masterTonalGain = new Tone.Gain(0);
Expand All @@ -30,28 +38,28 @@ export class TR808Snare {
gainHigh.connect(masterTonalGain);
masterTonalGain.connect(this.destination);

masterTonalGain.gain.setValueAtTime(1, time);
masterTonalGain.gain.setValueAtTime(velocity, time);
// Tonal body decay is short (~200ms)
masterTonalGain.gain.exponentialRampToValueAtTime(0.001, time + 0.2);
masterTonalGain.gain.exponentialRampToValueAtTime(0.001, time + 0.2 * decayVariance);

// Snappy Layer
const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
// High-pass filter (>1800Hz) to prevent phase trap with tonal body
const noiseFilter = new Tone.Filter(1800, "highpass");
const noiseFilter = new Tone.Filter(1800 * filterVariance, "highpass");
const snappyGain = new Tone.Gain(0);

noiseSrc.connect(noiseFilter);
noiseFilter.connect(snappyGain);
snappyGain.connect(this.destination);

// Snappy decay range: 0.25s to 0.4s
const snappyDecay = 0.25 + snappy * 0.15;
const snappyDecay = (0.25 + snappy * 0.15) * decayVariance;

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 + 0.2);
oscHigh.start(time).stop(time + 0.2);
oscLow.start(time).stop(time + 0.2 * decayVariance);
oscHigh.start(time).stop(time + 0.2 * decayVariance);
noiseSrc.start(time).stop(time + snappyDecay + 0.1);

// Cleanup
Expand Down
25 changes: 16 additions & 9 deletions src/logic/drums/TR909Kick.ts
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Expand Up @@ -6,49 +6,56 @@ export class TR909Kick {
constructor(private destination: Tone.ToneAudioNode) {
const sampleRate = Tone.getContext().sampleRate;
const bufferSize = sampleRate * 0.05; // 50ms click
this.noiseBuffer = Tone.getContext().createBuffer(1, bufferSize, sampleRate);
this.noiseBuffer = (Tone.getContext().rawContext as AudioContext).createBuffer(1, bufferSize, sampleRate);
const data = this.noiseBuffer.getChannelData(0);
for (let i = 0; i < bufferSize; 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) {
// pitch: 0.5 -> 50Hz, maps to 45-55Hz
const tune = 45 + pitch * 10;

// Micro-randomization on filter and decay (+/- 2%)
const filterVariance = 1 + (Math.random() * 0.04 - 0.02);
const decayVariance = 1 + (Math.random() * 0.04 - 0.02);

// decay: 0.5 -> 0.45s, maps to 0.3-0.6s
const decayTime = 0.3 + decay * 0.3;
const decayTime = (0.3 + decay * 0.3) * decayVariance;

// 909 Kick Body: Triangle Oscillator
const bodyOsc = new Tone.Oscillator(tune * 4.7, "triangle");
bodyOsc.phase = Math.random() * 360; // Analog phase randomization
const bodyGain = new Tone.Gain(0);

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

// Aggressive Pitch Envelope: Start at Tune * 4.7 (~235Hz) and drop over 100ms
const startFreq = tune * 4.7;
const endFreq = tune;
const drift = (Math.random() * 2 - 1) * 0.5; // Pitch Drift (+/- 0.5Hz)
const startFreq = tune * 4.7 + drift;
const endFreq = tune + drift;

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

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

// Click Layer (Noise)
const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
const noiseFilter = new Tone.Filter(1000, "highpass"); // HPF > 1kHz to avoid phase trap
const noiseFilter = new Tone.Filter(1000 * filterVariance, "highpass"); // HPF > 1kHz to avoid phase trap
const noiseGain = new Tone.Gain(0);

noiseSrc.connect(noiseFilter);
noiseFilter.connect(noiseGain);
noiseGain.connect(this.destination);

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

bodyOsc.start(time).stop(time + decayTime);
Expand Down
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