PedalKernel

Real components. Real circuits. Real tone.

Write a schematic in .pedal files. Hear it. Build it.

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What is PedalKernel?

PedalKernel is a circuit-to-audio compiler. You describe a pedal the way you'd draw it on a napkin -- resistors, caps, diodes, tubes, pots, with real values and real wiring -- and PedalKernel compiles it into a real-time audio engine using Wave Digital Filters.

The same .pedal file exports to KiCad for PCB layout and generates a Mouser bill of materials. Design the tone first, then solder it.

Every component shapes the sound the way the physical part would. A 220nF cap in the feedback loop rolls off differently than a 100nF. Germanium diodes clip softer than silicon. A 12AX7 saturates differently than a 12AU7. There are no "models" or "algorithms" to choose from -- just the circuit.

Quick example

pedal "Tube Screamer" {
  components {
    R1: resistor(4.7k)       # These values are the tone
    C1: cap(220n)             # Change them and the sound changes
    D1: diode_pair(silicon)   # Si clips harder than Ge
    Gain: pot(500k)
  }
  nets {
    in -> C1.a
    C1.b -> R1.a, D1.a
    D1.b -> gnd
    R1.b -> Gain.a
    Gain.b -> out
  }
  controls {
    Gain.position -> "Drive" [0.0, 1.0] = 0.5
  }
}

Quick start

git clone https://github.com/ajmwagar/pedalkernel
cd pedalkernel
cargo build --release
cargo test

# Render a pedal file to WAV
cargo run --example process -- pedalkernel/examples/pedals/overdrive/tube_screamer.pedal

# Interactive TUI -- tweak knobs in real time
cargo run --example tui --features tui -- pedalkernel/examples/pedals/overdrive/tube_screamer.pedal

From tone to PCB

The same .pedal file drives three outputs:

                          +---> WDF audio engine ---> WAV / JACK real-time
                          |
  .pedal file ---> parse -+---> KiCad netlist ---> PCB layout
                          |
                          +---> Bill of Materials ---> Mouser order

What's included

12 pedals spanning overdrive, fuzz, distortion, modulation, compression, delay:

• Tube Screamer, Blues Driver, Klon Centaur, Fulltone OCD (overdrives)
• Fuzz Face, Big Muff (fuzz)
• ProCo RAT (distortion)
• MXR Phase 90 (phaser)
• Boss CE-2 (modulation)
• Dyna Comp (compressor)
• Boss DM-2, Memory Man (delays)

3 tube amps:

• Tweed Deluxe 5E3, Bassman 5F6-A, Marshall JTM45

3 synth modules:

• CEM3340 VCO, Moog Ladder VCF, Minisynth (complete mono voice)

Full component reference and circuit details in docs/components.md.

Feature flags

Feature	Default	What it adds
jack-rt	Yes	JACK real-time audio -- sub-5ms latency
tui	Yes	Interactive ASCII control surface
cli	Yes	Command-line interface
hardware	No	BOM generation, voltage checks, .pedalhw specs
gummel-poon	Yes	Advanced BJT modeling with base charge effects
debug-trace	No	Detailed signal-level tracing for debugging
solver-stats	No	WDF solver statistics
fault-injection	No	Injected faults for test validation
runtime-warnings	No	Warnings for out-of-range device operation
pro-pedals	No	Tests that reference private pedalkernel-pro circuits

Minimal DSP-only build:

cargo build --no-default-features

Documentation

• Components Reference — All available component types, syntax, and variants
• How it works — WDF compilation pipeline and circuit solving
• Performance — Benchmarks, CPU usage, scalability
• Hardware export — KiCad export, BOM generation, voltage checks
• Python tools — Schematic rendering, BOM generation
• Rust API — Parsing, compilation, and real-time processing
• Physical realism — How circuits match real hardware behavior
• UI manifests — Control surface definitions (for VST UI generation)

Performance

All pedals run comfortably in real-time. Tube Screamer: 1.2% CPU at 48 kHz. Big Muff: 1.7%. Even the most complex circuits stay under 6% with room to spare. Full benchmark details in docs/performance.md.

License

AGPLv3 (c) Avery Wagar