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README.md

Flues Drumkit - Hardcore Industrial TR-909

A hardcore industrial drum synthesizer LV2 plugin with 11 voices inspired by the TR-909 but pushed into aggressive territory. Designed for industrial, EBM, and harsh electronic music.

Features

  • 11 Synthesized Drum Voices (not samples!)
  • 43 Parameters with X11/Cairo GUI
  • Velocity Sensitivity on kick, snare, and toms
  • Hi-Hat Choke Group (closed kills open)
  • Master FX Chain: Bit Crusher, Distortion, Reverb
  • Stereo Output with fixed per-voice placement across the panorama
  • MIDI Channel Omni (responds to all channels)

MIDI Note Mapping

MIDI Note Note Name Drum Voice Velocity Sensitive
36 C2 Kick Yes
39 Eb2 Clap No (fixed level)
40 E2 Snare Yes
41 F2 Crash No (fixed level)
42 F#2 Closed Hi-Hat No (fixed level)
45 A2 Lo Tom Yes
46 A#2 Open Hi-Hat No (fixed level)
50 D3 Hi Tom Yes
51 Eb3 Bash (Metal) Yes
52 E3 Cowbell Yes
53 F3 Clave Yes

Note: When Closed Hi-Hat (42) is triggered, it immediately silences Open Hi-Hat (46) for realistic behavior.

Synthesis Methods

Kick Drum (5 Parameters)

  • Pitch: Starting frequency 60-250 Hz (exponential pitch envelope sweep)
  • Decay: Envelope decay time 50-1500ms
  • Drive: Tanh saturation 1.0-10× (adds harmonics)
  • Punch: High-frequency click enhancement 0-100%
  • Level: Per-voice output gain

Synthesis: Pitch envelope → Sine oscillator → Distortion → HPF noise burst → DC blocker

Snare Drum (3 Parameters)

  • Tone: Body/shell balance with resonator retuning and upper-mid crack emphasis
  • Snap: Noise level + HPF cutoff 700Hz-6.5kHz
  • Level: Per-voice output gain

Synthesis: Dual body/shell resonators + filtered noise burst + short crack resonator

Clap (3 Parameters)

  • Density: Impulse count (3-7) + spacing tightness (25-10ms) + burst length (3-7ms)
  • Tone: Bandpass center frequency 1000Hz-4500Hz + Q factor (4-8)
  • Level: Per-voice output gain

Synthesis: Multi-impulse noise bursts → Resonant bandpass filter (Q=4-8) → Envelope

Toms (3 Parameters, Shared)

  • Tom 1 Pitch/Decay/Level: Lo tom 60-150Hz, 80-800ms
  • Tom 2 Pitch/Decay/Level: Hi tom 150-400Hz, 80-800ms

Synthesis: Pitch envelope → mixed sine/triangle body → resonant knock transient → soft clipping

Hi-Hats (6 Parameters, Split)

  • Closed Brightness/Decay/Level: Brightness lift 5.5-14.5kHz, 50-200ms
  • Open Brightness/Decay/Level: Brightness lift 5.5-14.5kHz, 200-1200ms

Synthesis: 6× inharmonic square wave oscillators → metallic cross-ring mix → noise/sizzle bands → saturation

Crash (3 Parameters)

  • Brightness: Bandpass center shift 1.5kHz-10kHz
  • Decay: Envelope decay 300-2500ms
  • Level: Per-voice output gain

Synthesis: White noise → 3× bandpass cascade → Soft clipping

Cowbell (3 Parameters)

  • Tone: Dual oscillator pitch 380-1400 Hz
  • Decay: Envelope decay 50-1000 ms
  • Level: Per-voice output gain

Synthesis: Dual square/sine oscillators → bandpass → saturation

Clave (3 Parameters)

  • Tone: Resonant click pitch 900-4200 Hz
  • Decay: Envelope decay 20-400 ms
  • Level: Per-voice output gain

Synthesis: Noise burst → resonant bandpass → envelope

Bash (7 Parameters)

  • Size: Base plate/pipe frequency (180-1200 Hz)
  • Spread: Inharmonic overtone spread for clang and beating
  • Decay: Ring-out time 120-1600 ms
  • Drive: Per-voice tanh saturation 1-10×
  • Noise: Strike noise burst level
  • Edge: Highpass lift 800-8000 Hz for metallic bite
  • Level: Per-voice output gain

Synthesis: Dual detuned sine/ring-mod core → highpass strike + noise burst → dual bandpass resonators → tanh saturation

Master FX (4 Parameters)

  • Bit Crush: Bit depth reduction 0=off, 1=2-bit (lo-fi destruction)
  • Drive: Master distortion 1.0-5.0× tanh saturation
  • Reverb: Schroeder reverb level 0-60% (fixed room size)
  • Gain: Master output level 0-100%

Signal Flow

MIDI Note → Voice Synthesis → Stereo Voice Panner
    ↓
Bit Crusher (dual mono master bus)
    ↓
Master Distortion (dual mono tanh)
    ↓
Reverb (left/right tanks)
    ↓
DC Blocker (per channel, R=0.999)
    ↓
Master Gain
    ↓
Audio Out L/R

Installation

cd lv2/drumkit
cmake -S . -B build
cmake --build build
cmake --install build --prefix ~/.lv2

Verify installation:

lv2ls | grep drumkit
lv2info https://danja.github.io/flues/plugins/drumkit

Usage

In a DAW (Reaper, Ardour, Carla, etc.)

  1. Load "Flues Drumkit" as an instrument track
  2. Send MIDI notes in the range C2-D3 (notes 36-50, with B2/47 triggering Bash)
  3. Adjust parameters via the GUI or DAW automation
  4. Tip: Use MIDI velocity on kick/snare/toms for dynamics

Sound Design Tips

Aggressive Kick:

  • Pitch: 0.2-0.4 (60-100 Hz starting point)
  • Decay: 0.3-0.5 (medium decay)
  • Drive: 0.5-0.8 (heavy distortion)
  • Punch: 0.3-0.5 (add click attack)

Metallic Snare:

  • Tone: 0.7-0.9 (emphasize shell resonator, high Q)
  • Snap: 0.6-0.8 (bright, cutting snap)

Snappy Clap:

  • Density: 0.7-0.9 (7 impulses, tight spacing, longer bursts)
  • Tone: 0.5-0.8 (bright, cutting, high Q resonance)

Bash Metal Hits:

  • Size: 0.3-0.5 (mid-sized plate), Spread: 0.6-0.9 for harsh beating
  • Drive: 0.6-0.8, Noise: 0.6-0.8, Edge: 0.7-1.0 for serrated attack

Harsh Hi-Hats:

  • Brightness: 0.7-1.0 (8-12kHz, very bright)
  • Decay: Adjust per pattern (short for techno, long for ambient)

Master Processing:

  • Bit Crush: 0.2-0.4 for subtle grit, 0.7+ for lo-fi destruction
  • Drive: 0.3-0.5 for cohesive saturation
  • Reverb: 0.1-0.3 for industrial ambience

Performance Tips

  1. Hi-Hat Choke: Play closed HH to cut off open HH naturally
  2. Velocity Expression: Use MIDI velocity on kick/snare/toms for dynamics
  3. Layering: Combine multiple voices (e.g., kick + clap) for hybrid sounds
  4. Automation: Automate Drive and Bit Crush for evolving textures

Technical Details

  • Sample Rate: 48kHz (native)
  • Latency: Zero (real-time synthesis)
  • Polyphony: 11 voices (one per drum, monophonic)
  • CPU Usage: ~5-8% (single core, all voices active)
  • Output Level: Calibrated to ~-6dB peak with all drums

Architecture

DSP Modules (7 total):

  • NoiseGenerator.hpp - LCG white noise
  • ADEnvelope.hpp - Attack/decay envelope
  • PitchEnvelope.hpp - Exponential pitch sweep
  • BiquadFilter.hpp - Bandpass/highpass filtering
  • Distortion.hpp - Tanh soft clipping
  • Bitcrusher.hpp - Bit depth reduction
  • DCBlocker.hpp - DC offset removal

Drum Voices (7 types, 9 instances):

  • KickVoice.hpp - 4 parameters
  • SnareVoice.hpp - 2 parameters
  • ClapVoice.hpp - 2 parameters
  • TomVoice.hpp - 2 parameters (shared between lo/hi)
  • HiHatVoice.hpp - 2 parameters (shared between closed/open)
  • CrashVoice.hpp - 2 parameters
  • BashVoice.hpp - 6 parameters

UI: X11/Cairo with 28 rotary knobs organized in 6 rows by function

References

  • Inspired by Roland TR-909 (1984)
  • Industrial sound design from NIN, Ministry, Front 242
  • Physical modeling techniques from Karplus-Strong and resonant synthesis

License

MIT License - Part of the Flues synthesis project

Author

Danny Ayers - https://danja.github.io/flues/