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Implement research-based analog drum synthesis #27

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35 changes: 15 additions & 20 deletions src/logic/DrumMachine.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ import { TR808Clap } from './drums/TR808Clap'
export class DrumMachine {
comp: Tone.Compressor
shaper: Tone.WaveShaper
output: Tone.Gain // Optional master output
output: Tone.Gain // Master output
outputKick: Tone.Gain
outputSnare: Tone.Gain
outputHihat: Tone.Gain
Expand Down Expand Up @@ -40,24 +40,25 @@ export class DrumMachine {

constructor() {
this.comp = new Tone.Compressor(-24, 4)
this.shaper = new Tone.WaveShaper(this.makeDistortionCurve(15))
// Research saturation amount/formula
this.shaper = new Tone.WaveShaper(this.makeDistortionCurve(20))
this.shaper.oversample = '4x'

this.output = new Tone.Gain(1)
this.outputKick = new Tone.Gain(1)
this.outputSnare = new Tone.Gain(1)
this.outputHihat = new Tone.Gain(1)
this.outputOpenHat = new Tone.Gain(1)
this.outputClap = new Tone.Gain(1)

this.comp.chain(this.shaper, this.output, Tone.Destination)
// Route through compression and saturation for "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)

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

this.kit808 = {
kick: new TR808Kick(this.outputKick),
Expand All @@ -69,7 +70,7 @@ export class DrumMachine {
this.kit909 = {
kick: new TR909Kick(this.outputKick),
snare: new TR909Snare(this.outputSnare),
hihat: new TR808HiHat(this.outputHihat), // Shared hihat synthesis for now
hihat: new TR808HiHat(this.outputHihat),
clap: new TR808Clap(this.outputClap)
}
}
Expand All @@ -80,6 +81,7 @@ export class DrumMachine {
const curve = new Float32Array(n_samples)
const deg = Math.PI / 180
for (let i = 0; i < n_samples; ++i) {
// Formula from research: curve[i] = (3 + k) * x * 20 * deg / (Math.PI + k * Math.abs(x))
let x = i * 2 / n_samples - 1
curve[i] = (3 + k) * x * 20 * deg / (Math.PI + k * Math.abs(x))
}
Expand Down Expand Up @@ -112,14 +114,7 @@ export class DrumMachine {
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':
// 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.
break
case 'hihatOpen': kit909.hihat.trigger(time, true, p.pitch, p.decay); break
case 'clap': kit909.clap.trigger(time, p.pitch, p.decay); break
}
}
Expand Down
31 changes: 22 additions & 9 deletions src/logic/drums/TR808HiHat.ts
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@@ -1,27 +1,40 @@
import * as Tone from 'tone'

export class TR808HiHat {
// Exact frequencies from research: 205.3, 304.4, 369.6, 522.7, 800, 540 Hz
private frequencies = [205.3, 304.4, 369.6, 522.7, 800, 540];

constructor(private destination: Tone.ToneAudioNode) { }

trigger(time: number, isOpen: boolean, pitch: number, decay: number) {
const mixGain = new Tone.Gain(0.15);
// Mixer for the 6 square waves
const mixGain = new Tone.Gain(0.15); // Attenuate to avoid clipping
const oscillators = this.frequencies.map(freq => {
const osc = new Tone.Oscillator(freq, "square");

// Micro-randomization: Analog Drift (+/- 2Hz)
const drift = (Math.random() - 0.5) * 4;
// Use pitch to shift all frequencies slightly
const osc = new Tone.Oscillator(freq * (0.5 + pitch) + drift, "square");
// Apply pitch multiplier (0.8x to 1.2x) while keeping hardware ratios
const pitchMultiplier = 0.8 + pitch * 0.4;
osc.frequency.value = (freq * pitchMultiplier) + drift;

osc.connect(mixGain);
return osc;
});

const bpf1 = new Tone.Filter(3500, "bandpass"); // 3.5kHz
// Parallel Bandpass Filters: 3440Hz and 7100Hz with Q=1.5
const bpf1 = new Tone.Filter(3440, "bandpass");
bpf1.Q.value = 1.5;
const bpf2 = new Tone.Filter(7000, "bandpass"); // 7kHz
const bpf2 = new Tone.Filter(7100, "bandpass");
bpf2.Q.value = 1.5;

// Micro-randomization: Filter Cutoff (+/- 2%)
bpf1.frequency.value = (bpf1.frequency.value as any) * (1 + (Math.random() * 0.04 - 0.02));
bpf2.frequency.value = (bpf2.frequency.value as any) * (1 + (Math.random() * 0.04 - 0.02));

const envGain = new Tone.Gain(0);
const hpf = new Tone.Filter(7000, "highpass"); // 7kHz high-pass cleanup
// Final HPF: 7000Hz cleanup (Sizzle)
const hpf = new Tone.Filter(7000, "highpass");

mixGain.connect(bpf1);
mixGain.connect(bpf2);
Expand All @@ -30,8 +43,8 @@ export class TR808HiHat {
envGain.connect(hpf);
hpf.connect(this.destination);

// decay: 0.5 maps to standard 808 times
const decayTime = isOpen ? (0.2 + decay * 0.8) : (0.02 + decay * 0.1);
// Decay: Closed (40-60ms), Open (300-500ms)
const decayTime = isOpen ? (0.3 + decay * 0.2) : (0.04 + decay * 0.02);

envGain.gain.setValueAtTime(1, time);
envGain.gain.exponentialRampToValueAtTime(0.001, time + decayTime);
Expand All @@ -40,7 +53,7 @@ export class TR808HiHat {
osc.start(time).stop(time + decayTime);
});

// Disposal
// Disposal anchored to first oscillator
oscillators[0].onstop = () => {
oscillators.forEach(o => o.dispose());
mixGain.dispose();
Expand Down
35 changes: 9 additions & 26 deletions src/logic/drums/TR808Kick.ts
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Expand Up @@ -4,10 +4,10 @@ export class TR808Kick {
constructor(private destination: Tone.ToneAudioNode) { }

trigger(time: number, pitch: number, decay: number) {
// pitch: 0.5 -> 50Hz, maps to 40-80Hz range
const tune = 40 + pitch * 40;
// decay: 0.5 -> 1.5s, maps to 0.1-3.0s range
const decayTime = 0.1 + decay * 2.9;
// pitch: 0.5 -> 52.5Hz, maps to 45-60Hz range according to research
const tune = 45 + pitch * 15;
// decay: 0.5 -> 1.7s, maps to 0.4-3.0s range according to research
const decayTime = 0.4 + decay * 2.6;

// 808 Kick Core: Bridged-T Network emulation
const osc = new Tone.Oscillator(tune, "sine");
Expand All @@ -17,11 +17,12 @@ export class TR808Kick {
osc.connect(masterGain);
masterGain.connect(this.destination);

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

// Pitch Envelope: Start high (~150Hz) and drop quickly to simulate the membrane hit
const startFreq = 150 + drift;
// Pitch Envelope: Start high (Tune * 2.5) and drop quickly to simulate the membrane hit
// Research: Tune * 2.5 (approx 120-150 Hz), Pitch Decay 0.04 - 0.06 sec
const startFreq = (tune * 2.5) + drift;
const endFreq = tune + drift;
const pitchDropTime = 0.05; // 50ms drop

Expand All @@ -32,29 +33,11 @@ export class TR808Kick {
masterGain.gain.setValueAtTime(1, time);
masterGain.gain.exponentialRampToValueAtTime(0.001, time + decayTime);

// Attack Click: Dirac impulse / very fast transient generator
const clickOsc = new Tone.Oscillator(startFreq * 2, "sine");
const clickGain = new Tone.Gain(0);
clickOsc.connect(clickGain);
clickGain.connect(this.destination);

clickOsc.frequency.setValueAtTime(startFreq * 2, time);
clickOsc.frequency.exponentialRampToValueAtTime(10, time + 0.02);

clickGain.gain.setValueAtTime(0.5, time);
clickGain.gain.exponentialRampToValueAtTime(0.001, time + 0.01);

osc.start(time).stop(time + decayTime);
clickOsc.start(time).stop(time + 0.02);

osc.onstop = () => {
osc.dispose();
masterGain.dispose();
};

clickOsc.onstop = () => {
clickOsc.dispose();
clickGain.dispose();
};
}
}
37 changes: 24 additions & 13 deletions src/logic/drums/TR808Snare.ts
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Expand Up @@ -6,20 +6,26 @@ 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) {
// pitch maps to tone balance here (balance between low and high modes)
// pitch maps to tone balance (balance between low and high modes)
const toneBalance = pitch;

// 808 Membrane modes: ~180Hz and ~330Hz
const oscLow = new Tone.Oscillator(180 + (pitch * 50), "sine");
const oscHigh = new Tone.Oscillator(330 + (pitch * 80), "sine");
// 808 Membrane modes: Fixed frequencies 238Hz and 476Hz according to research
const oscLow = new Tone.Oscillator(238, "sine");
const oscHigh = new Tone.Oscillator(476, "sine");

// Micro-randomization: Pitch Drift
const drift = (Math.random() * 2 - 1);
oscLow.frequency.value = (oscLow.frequency.value as any) + drift;
oscHigh.frequency.value = (oscHigh.frequency.value as any) + drift;

const gainLow = new Tone.Gain(1 - toneBalance);
const gainHigh = new Tone.Gain(toneBalance);
const masterTonalGain = new Tone.Gain(0);
Expand All @@ -31,26 +37,31 @@ export class TR808Snare {
masterTonalGain.connect(this.destination);

masterTonalGain.gain.setValueAtTime(1, time);
masterTonalGain.gain.exponentialRampToValueAtTime(0.001, time + 0.15);
masterTonalGain.gain.exponentialRampToValueAtTime(0.001, time + 0.2); // Tonal decay ~200ms

// Snappy Layer
const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
// Apply HPF (~2kHz) to noise to prevent phase cancellation with tonal oscillators
const noiseFilter = new Tone.Filter(2000, "highpass");
// HPF (~1800Hz) to noise to prevent phase cancellation
const noiseFilter = new Tone.Filter(1800, "highpass");

// Micro-randomization: Filter Cutoff (+/- 2%)
noiseFilter.frequency.value = (noiseFilter.frequency.value as any) * (1 + (Math.random() * 0.04 - 0.02));

const snappyGain = new Tone.Gain(0);

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

const snappyDecay = 0.1 + snappy * 0.4; // 0.1s to 0.5s
// snappyDecay: 0.25s to 0.4s range according to research
const snappyDecayTime = 0.25 + snappy * 0.15;

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

oscLow.start(time).stop(time + 0.15);
oscHigh.start(time).stop(time + 0.15);
noiseSrc.start(time).stop(time + snappyDecay);
oscLow.start(time).stop(time + 0.2);
oscHigh.start(time).stop(time + 0.2);
noiseSrc.start(time).stop(time + snappyDecayTime);

// Cleanup
oscLow.onstop = () => {
Expand Down
42 changes: 27 additions & 15 deletions src/logic/drums/TR909Kick.ts
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Expand Up @@ -2,31 +2,41 @@ import * as Tone from 'tone'

export class TR909Kick {
private noiseBuffer: AudioBuffer;
private distortionCurve: Float32Array;

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;
}

// Pre-calculate distortion curve for tanh soft clipping
this.distortionCurve = this.makeDistortionCurve(1.5);
}

private makeDistortionCurve(amount: number) {
const n_samples = 44100;
const curve = new Float32Array(n_samples);
for (let i = 0; i < n_samples; ++i) {
let x = i * 2 / n_samples - 1;
curve[i] = Math.tanh(x * amount);
}
return curve;
}

trigger(time: number, pitch: number, decay: number) {
// pitch: 0.5 -> 50Hz, maps to 45-65Hz
const tune = 45 + pitch * 20;
// decay: 0.5 -> 0.45s, maps to 0.2-0.7s
const decayTime = 0.2 + decay * 0.5;
// pitch: 0.5 -> 50Hz, maps to 45-55Hz according to research
const tune = 45 + pitch * 10;
// decay: 0.5 -> 0.45s, maps to 0.3-0.6s according to research
const decayTime = 0.3 + decay * 0.3;

// 909 Kick Core: Triangle + Soft Clipper
const bodyOsc = new Tone.Oscillator(230, "triangle");
const bodyOsc = new Tone.Oscillator(tune * 4.7, "triangle");

// Custom Soft Clipper WaveShaper
const clipper = new Tone.WaveShaper((val) => {
// Hyperbolic tangent (tanh) soft clipping
return Math.tanh(val * 1.5);
});
const clipper = new Tone.WaveShaper(this.distortionCurve);

const bodyGain = new Tone.Gain(0);

Expand All @@ -35,19 +45,21 @@ export class TR909Kick {
bodyGain.connect(this.destination);

// Aggressive Pitch Envelope: High start -> punch
const startFreq = 230 + (pitch * 50); // Start high for the punch
// Research: Start 4.7x base frequency (200-250Hz), decay 0.05 - 0.15 sec
const startFreq = tune * 4.7;
const endFreq = tune;

bodyOsc.frequency.setValueAtTime(startFreq, time);
bodyOsc.frequency.exponentialRampToValueAtTime(endFreq, time + 0.04); // Fast 40ms drop
bodyOsc.frequency.exponentialRampToValueAtTime(endFreq, time + 0.1); // 100ms drop

// VCA Envelope
bodyGain.gain.setValueAtTime(1, 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
// HPF around 1000-2000Hz
const noiseFilter = new Tone.Filter(1500, "highpass");
const noiseGain = new Tone.Gain(0);

noiseSrc.connect(noiseFilter);
Expand All @@ -56,7 +68,7 @@ export class TR909Kick {

// Ultra short envelope (10-20ms)
const clickDecay = 0.015;
noiseGain.gain.setValueAtTime(0.8, time);
noiseGain.gain.setValueAtTime(0.7, time);
noiseGain.gain.exponentialRampToValueAtTime(0.001, time + clickDecay);

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