Authentic Analog Drum Synthesis Implementation

src/logic/DrumMachine.ts

@@ -99,6 +99,17 @@ export class DrumMachine {
         this.params[drum] = { pitch, decay }
     }
 
+    /**
+     * Synchronizes all internal parameters from an external state.
+     */
+    syncInternalParams(kit: '808' | '909', drive: number, drumParams: Record<string, { pitch: number, decay: number }>) {
+        this.setKit(kit)
+        this.setSaturation(drive)
+        Object.entries(drumParams).forEach(([id, p]) => {
+            this.setDrumParams(id, p.pitch, p.decay)
+        })
+    }
+
     triggerDrum(drum: 'kick' | 'snare' | 'hihat' | 'hihatOpen' | 'clap' | 'cowbell', time: number, velocity: number = 0.8) {
         const p = this.params[drum]
         const kit808 = this.kit808

src/logic/DrumUtils.ts

@@ -1,7 +1,47 @@
+import * as Tone from 'tone'
+
 /**
  * Shared DSP utilities for drum synthesis based on research specs.
  */
 
+/**
+ * Generates a white noise buffer.
+ * @param context - Tone.js or Web Audio context
+ * @param duration - Duration in seconds
+ */
+export function generateWhiteNoise(context: Tone.BaseContext, duration: number = 2.0): AudioBuffer {
+    const sampleRate = context.sampleRate;
+    const bufferSize = Math.floor(sampleRate * duration);
+    const buffer = context.createBuffer(1, bufferSize, sampleRate);
+    const data = buffer.getChannelData(0);
+    for (let i = 0; i < bufferSize; i++) {
+        data[i] = Math.random() * 2 - 1;
+    }
+    return buffer;
+}
+
+/**
+ * Generates a 15-bit LFSR (pseudo-random) noise buffer.
+ * Uses characteristic polynomial x^15 + x^14 + 1.
+ * @param context - Tone.js or Web Audio context
+ * @param duration - Duration in seconds
+ */
+export function generateLFSRNoise(context: Tone.BaseContext, duration: number = 2.0): AudioBuffer {
+    const sampleRate = context.sampleRate;
+    const bufferSize = Math.floor(sampleRate * duration);
+    const buffer = context.createBuffer(1, bufferSize, sampleRate);
+    const data = buffer.getChannelData(0);
+
+    let lfsr = 0x7FFF; // 15-bit state
+    for (let i = 0; i < bufferSize; i++) {
+        // Galois LFSR for x^15 + x^14 + 1
+        const bit = ((lfsr >> 14) ^ (lfsr >> 13)) & 1;
+        lfsr = ((lfsr << 1) | bit) & 0x7FFF;
+        data[i] = (lfsr / 0x3FFF) - 1.0;
+    }
+    return buffer;
+}
+
 /**
  * Creates a soft-clipping saturation curve (hyperbolic tangent approximation).
  * Formula: (3 + k) * x * 20 * deg / (Math.PI + k * Math.abs(x))

src/logic/drums/TR808Clap.ts

@@ -1,18 +1,16 @@
 import * as Tone from 'tone'
-import { applyVariance } from '../DrumUtils'
+import { applyVariance, generateWhiteNoise } from '../DrumUtils'
 
 export class TR808Clap {
     private noiseBuffer: AudioBuffer;
 
     constructor(private destination: Tone.ToneAudioNode) {
-        const sampleRate = Tone.getContext().sampleRate;
-        this.noiseBuffer = Tone.getContext().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;
+        this.noiseBuffer = generateWhiteNoise(Tone.getContext(), 2.0);
     }
 
     trigger(time: number, pitch: number, decay: number, velocity: number = 0.8) {
         const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
+        const randomStart = Math.random() * (this.noiseBuffer.duration - 0.6);
         const bpfFreq = (1000 + pitch * 1000);
         const bpf = new Tone.Filter(applyVariance(bpfFreq, 0.02), "bandpass");
         const gain = new Tone.Gain(0).connect(this.destination);
@@ -39,7 +37,7 @@ export class TR808Clap {
         gain.gain.setValueAtTime(velocity, finalDecayStart);
         gain.gain.exponentialRampToValueAtTime(0.001, finalDecayStart + decayTime);
 
-        noiseSrc.start(time).stop(finalDecayStart + decayTime);
+        noiseSrc.start(time, randomStart).stop(finalDecayStart + decayTime);
 
         noiseSrc.onended = () => {
             noiseSrc.dispose();

src/logic/drums/TR808Cowbell.ts

@@ -7,6 +7,8 @@ export class TR808Cowbell {
     constructor(private destination: Tone.ToneAudioNode) { }
 
     trigger(time: number, pitch: number, decay: number, velocity: number = 0.8) {
+        if (velocity <= 0) return;
+
         // Core: Dual square wave oscillators from Schmitt trigger matrix
         // Standard frequencies: 540Hz and 800Hz
         const pitchMultiplier = 0.5 + pitch; // Range approx 0.5x to 1.5x
@@ -15,6 +17,8 @@ export class TR808Cowbell {
 
         const osc1 = new Tone.Oscillator(freq1, "square");
         const osc2 = new Tone.Oscillator(freq2, "square");
+        osc1.phase = Math.random() * 360;
+        osc2.phase = Math.random() * 360;
 
         const mixGain = new Tone.Gain(0.5);
         const bpf = new Tone.Filter(applyVariance(800, 0.02), "bandpass");
@@ -30,15 +34,15 @@ export class TR808Cowbell {
 
         const decayTime = applyVariance(0.1 + decay * 0.4, 0.02);
 
-        vca.gain.setValueAtTime(velocity, time);
+        vca.gain.setValueAtTime(Math.max(0.001, velocity), time);
         vca.gain.exponentialRampToValueAtTime(0.001, time + decayTime);
 
         this.activeGains.add(vca);
 
         osc1.start(time).stop(time + decayTime);
         osc2.start(time).stop(time + decayTime);
 
-        osc1.onstop = () => {
+        const onEnd = () => {
             osc1.dispose();
             osc2.dispose();
             mixGain.dispose();
@@ -47,6 +51,9 @@ export class TR808Cowbell {
             vca.dispose();
             this.activeGains.delete(vca);
         };
+
+        osc1.onstop = onEnd;
+        setTimeout(onEnd, (decayTime + 0.5) * 1000);
     }
 
     stop(time: number) {

src/logic/drums/TR808HiHat.ts

@@ -8,6 +8,8 @@ export class TR808HiHat {
     constructor(private destination: Tone.ToneAudioNode) { }
 
     trigger(time: number, isOpen: boolean, pitch: number, decay: number, velocity: number = 0.8) {
+        if (velocity <= 0) return;
+
         // Create nodes
         const mixGain = new Tone.Gain(0.15);
         const bpf1 = new Tone.Filter(3440, "bandpass");
@@ -22,7 +24,7 @@ export class TR808HiHat {
         const oscillators = this.frequencies.map(freq => {
             const driftedFreq = applyPitchDrift(freq * pitchMultiplier, 2.0); // +/- 2Hz drift for hats
             const osc = new Tone.Oscillator(driftedFreq, "square");
-            osc.phase = Math.random() * 360;
+            osc.phase = Math.random() * 360; // Analog phase randomization
             osc.connect(mixGain);
             return osc;
         });
@@ -36,7 +38,7 @@ export class TR808HiHat {
         envGain.connect(hpf);
         hpf.connect(this.destination);
 
-        // Filter Q values and randomization
+        // Filter Q values and randomization from research
         bpf1.Q.value = 1.5;
         bpf2.Q.value = 1.5;
         bpf1.frequency.value = applyVariance(3440, 0.02);
@@ -48,7 +50,7 @@ export class TR808HiHat {
         const decayTime = applyVariance(decayBase, 0.02);
 
         // VCA Envelope
-        envGain.gain.setValueAtTime(velocity, time);
+        envGain.gain.setValueAtTime(Math.max(0.001, velocity), time);
         envGain.gain.exponentialRampToValueAtTime(0.001, time + decayTime);
 
         this.activeGains.add(envGain);
@@ -58,9 +60,8 @@ export class TR808HiHat {
             osc.start(time).stop(time + decayTime);
         });
 
-        // Disposal - Explicitly clean up all 11-12 nodes to prevent memory leaks
-        // We use the first oscillator's onstop event to trigger the cleanup
-        oscillators[0].onstop = () => {
+        // Disposal - Explicitly clean up nodes to prevent memory leaks
+        const onEnd = () => {
             oscillators.forEach(o => o.dispose());
             mixGain.dispose();
             bpf1.dispose();
@@ -69,6 +70,10 @@ export class TR808HiHat {
             hpf.dispose();
             this.activeGains.delete(envGain);
         };
+
+        // Use Tone.Oscillator.onstop for cleanup with a safety timeout
+        oscillators[0].onstop = onEnd;
+        setTimeout(onEnd, (decayTime + 0.5) * 1000);
     }
 
     stop(time: number) {

src/logic/drums/TR808Kick.ts

@@ -30,11 +30,18 @@ export class TR808Kick {
         osc.frequency.setValueAtTime(startFreq, time);
         osc.frequency.exponentialRampToValueAtTime(endFreq, time + 0.05);
 
-        // VCA Amp Envelope: Instant attack, adjustable exponential decay
-        masterGain.gain.setValueAtTime(velocity, time);
-        masterGain.gain.exponentialRampToValueAtTime(0.001, time + finalDecay);
-
-        osc.start(time).stop(time + finalDecay);
+        // VCA Amp Envelope: Two-stage decay to emulate diode damping
+        // Stage 1: Fast damping (20ms) to 50% volume
+        // Stage 2: Natural decay to 0
+        const dampingTime = 0.02;
+        const dampingValue = Math.max(0.001, velocity * 0.5);
+        const safeFinalDecay = Math.max(dampingTime + 0.01, finalDecay);
+
+        masterGain.gain.setValueAtTime(Math.max(0.001, velocity), time);
+        masterGain.gain.exponentialRampToValueAtTime(dampingValue, time + dampingTime);
+        masterGain.gain.exponentialRampToValueAtTime(0.001, time + safeFinalDecay);
+
+        osc.start(time).stop(time + safeFinalDecay);
 
         osc.onstop = () => {
             osc.dispose();

src/logic/drums/TR808Snare.ts

@@ -1,17 +1,11 @@
 import * as Tone from 'tone'
-import { applyPitchDrift, applyVariance } from '../DrumUtils'
+import { applyPitchDrift, applyVariance, generateWhiteNoise } from '../DrumUtils'
 
 export class TR808Snare {
     private noiseBuffer: AudioBuffer;
 
     constructor(private destination: Tone.ToneAudioNode) {
-        const sampleRate = Tone.getContext().sampleRate;
-        const bufferSize = sampleRate * 0.5; // 500ms
-        this.noiseBuffer = Tone.getContext().createBuffer(1, bufferSize, sampleRate);
-        const data = this.noiseBuffer.getChannelData(0);
-        for (let i = 0; i < data.length; i++) {
-            data[i] = Math.random() * 2 - 1;
-        }
+        this.noiseBuffer = generateWhiteNoise(Tone.getContext(), 2.0);
     }
 
     trigger(time: number, pitch: number, snappy: number, velocity: number = 0.8) {
@@ -48,6 +42,7 @@ export class TR808Snare {
 
         // Snappy Layer
         const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
+        const randomStart = Math.random() * (this.noiseBuffer.duration - 0.5);
         // High-pass filter (>1800Hz) to prevent phase trap with tonal body
         // Q = 0.707 (Butterworth)
         const noiseFilter = new Tone.Filter({
@@ -66,7 +61,7 @@ export class TR808Snare {
 
         oscLow.start(time).stop(time + vcaDecay);
         oscHigh.start(time).stop(time + vcaDecay);
-        noiseSrc.start(time).stop(time + snappyDecay + 0.1);
+        noiseSrc.start(time, randomStart).stop(time + snappyDecay + 0.1);
 
         // Cleanup
         oscLow.onstop = () => {

src/logic/drums/TR909Kick.ts

@@ -1,5 +1,5 @@
 import * as Tone from 'tone'
-import { makeDistortionCurve, applyPitchDrift, applyVariance } from '../DrumUtils'
+import { makeDistortionCurve, applyPitchDrift, applyVariance, generateWhiteNoise } from '../DrumUtils'
 
 export class TR909Kick {
     private noiseBuffer: AudioBuffer;
@@ -8,14 +8,7 @@ export class TR909Kick {
     constructor(private destination: Tone.ToneAudioNode) {
         // Soft Clipping curve from research
         this.bodyCurve = makeDistortionCurve(10);
-
-        const sampleRate = Tone.getContext().sampleRate;
-        const bufferSize = sampleRate * 0.05; // 50ms click
-        this.noiseBuffer = Tone.getContext().createBuffer(1, bufferSize, sampleRate);
-        const data = this.noiseBuffer.getChannelData(0);
-        for (let i = 0; i < bufferSize; i++) {
-            data[i] = Math.random() * 2 - 1;
-        }
+        this.noiseBuffer = generateWhiteNoise(Tone.getContext(), 2.0);
     }
 
     trigger(time: number, pitch: number, decay: number, velocity: number = 0.8) {
@@ -58,6 +51,8 @@ export class TR909Kick {
 
         // Click Layer (Noise)
         const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
+        // Avoid "machine-gun" effect by randomizing start offset
+        const randomStart = Math.random() * (this.noiseBuffer.duration - 0.1);
         const noiseFilter = new Tone.Filter(noiseFilterFreq, "highpass"); // HPF > 1kHz to avoid phase trap
         const noiseGain = new Tone.Gain(0);
 
@@ -80,7 +75,7 @@ export class TR909Kick {
         pulseGain.gain.exponentialRampToValueAtTime(0.001, time + 0.005);
 
         bodyOsc.start(time).stop(time + vcaDecay);
-        noiseSrc.start(time).stop(time + clickDecay);
+        noiseSrc.start(time, randomStart).stop(time + clickDecay);
         pulseOsc.start(time).stop(time + 0.005);
 
         bodyOsc.onstop = () => {

src/logic/drums/TR909Snare.ts

@@ -1,5 +1,5 @@
 import * as Tone from 'tone'
-import { makeDistortionCurve, applyPitchDrift, applyVariance } from '../DrumUtils'
+import { makeDistortionCurve, applyPitchDrift, applyVariance, generateLFSRNoise } from '../DrumUtils'
 
 export class TR909Snare {
     private noiseBuffer: AudioBuffer;
@@ -8,15 +8,7 @@ export class TR909Snare {
     constructor(private destination: Tone.ToneAudioNode) {
         // Soft Clipping curve from research
         this.bodyCurve = makeDistortionCurve(15);
-
-        const sampleRate = Tone.getContext().sampleRate;
-        const bufferSize = sampleRate * 0.5;
-        this.noiseBuffer = Tone.getContext().createBuffer(1, bufferSize, sampleRate);
-        const data = this.noiseBuffer.getChannelData(0);
-        // While original used LFSR, research says Math.random() is sufficient for Web Audio API context
-        for (let i = 0; i < data.length; i++) {
-            data[i] = Math.random() * 2 - 1;
-        }
+        this.noiseBuffer = generateLFSRNoise(Tone.getContext(), 2.0);
     }
 
     trigger(time: number, pitch: number, snappy: number, velocity: number = 0.8) {
@@ -65,6 +57,7 @@ export class TR909Snare {
 
         // Snappy Layer
         const noiseSrc = new Tone.BufferSource(this.noiseBuffer);
+        const randomStart = Math.random() * (this.noiseBuffer.duration - 0.5);
         const hpf = new Tone.Filter(noiseHPFFreq, "highpass"); // HPF to protect fundamental
         // LPF controlled by 'Tone' (pitch parameter here), range 4kHz to 8kHz (research: toneCutoff)
         const toneCutoff = 4000 + pitch * 4000;
@@ -81,7 +74,7 @@ export class TR909Snare {
 
         osc1.start(time).stop(time + vcaDecay);
         osc2.start(time).stop(time + vcaDecay);
-        noiseSrc.start(time).stop(time + snappyDecay + 0.1);
+        noiseSrc.start(time, randomStart).stop(time + snappyDecay + 0.1);
 
         osc1.onstop = () => {
             osc1.dispose();

src/store/audioStore.ts

@@ -3,6 +3,7 @@ import * as Tone from 'tone'
 import { AcidSynth } from '../logic/AcidSynth'
 import { DrumMachine } from '../logic/DrumMachine'
 import { PadSynth } from '../logic/PadSynth'
+import { useDrumStore } from './instrumentStore'
 
 export interface AudioState {
     isInitialized: boolean
@@ -60,6 +61,17 @@ export const useAudioStore = create<AudioState>((set, get) => ({
         const drums = new DrumMachine()
         const pads = new PadSynth()
 
+        // Sync initial drum parameters from instrumentStore
+        const drumStore = useDrumStore.getState()
+        drums.syncInternalParams(drumStore.kit, drumStore.drive, {
+            kick: drumStore.kick,
+            snare: drumStore.snare,
+            hihat: drumStore.hihat,
+            hihatOpen: drumStore.hihatOpen,
+            clap: drumStore.clap,
+            cowbell: drumStore.cowbell
+        })
+
         Tone.Transport.bpm.value = get().bpm
         Tone.Transport.swing = get().swing