Performance System of a Modern Digital Luthier
California Institute of the Arts
Draft — ICMC target · instrument running today
Abstract
NEPTR is the brain at the center of the performance system, linking audio interfaces, DIY controllers, and hyper-instruments with internal DSP and a graphical interface. It replaces the laptop, the synthesizer, and the pedalboard onstage. Csound runs on a Raspberry Pi 5 at 48 kHz with a 128-sample period — 6 ms from string to amplifier — carrying 63 effect modules across 20 menus, with a Python touchscreen interface mirrored over OSC and the Rust DEMIURGE supervisor underneath. This paper documents the system as a whole rather than the box alone: the operating layer beneath it, the effect architecture inside it, and the family of DIY satellites around it.
Structure
- Introduction — the laptop, the synth, and the pedalboard, and why none of them are onstage
- Runtime — Csound on the Pi 5, 6 ms round trip, the Rust supervisor beneath
- Control surface — Teensy encoders, 20 menus, last-toggled-wins, the consistency test suite
- The effect roster — 63 hand-written modules; drive, spectral, granular, looper, NAM
- The performance system — hyper-trumpet, hyper-guitar, hemi speakers, We-Remote, 4-i-Gor, oFOOTS
- Evaluation — what survives a gig
- Future work
Resources
- DemiurgeOS — the platform it boots from
- NAM × Csound — the opcode at the end of its chain
- Hardware planets — the DIY satellites, with build files
- NEPTR on the site