CHOWTape for Schwung

Analog tape model audio effect for Schwung, based on the AnalogTapeModel by Jatin Chowdhury.

The core of the effect is a Jiles-Atherton magnetic hysteresis model, solved with a 4th-order Runge-Kutta integrator. This physically models how magnetic tape saturates, producing warm harmonic distortion and natural compression that varies with input level.

Features

• Hysteresis saturation — Jiles-Atherton model with RK4 solver for physically accurate tape distortion
• Tape speed / loss filter — Head loss modeling with speed-dependent HF rolloff and head bump resonance
• Wow & flutter — LFO-modulated delay with Ornstein-Uhlenbeck process for realistic pitch drift
• Chew — Tape damage simulation with random dropout events and filtering
• Degradation — Noise injection and lowpass filtering for worn tape character
• Tone control — Pre-tape tilt EQ with low and high shelving filters

Parameters

Knob	Description
Drive	Input level into the hysteresis model
Saturation	Magnetic saturation — lower = thicker/more compressed
Bias	Tape bias / width — changes harmonic character
Tone	Pre-tape tilt EQ (dark to bright)
Speed	Tape speed — affects HF loss and head bump
Flutter	Combined wow & flutter depth
Chew	Tape damage / dropout amount
Mix	Dry/wet balance

Additional parameters (accessible via chain editor): Degrade, Output.

Build

./scripts/build.sh      # Cross-compile for ARM64 via Docker
./scripts/install.sh    # Deploy to Move via SSH

Credits

• AnalogTapeModel by Jatin Chowdhury — original DSP algorithms
• Hysteresis model from DAFx paper by Jatin Chowdhury (Stanford CCRMA)

License

GPL-3.0-or-later — see LICENSE for details.

This is a derivative work of AnalogTapeModel, which is licensed under GPL-3.0.