Dev ships SunVox-based modular synth built mostly by Claude Code, cut CPU use 10x with Core Animation
jharsem · reddit · 2026-10-15
A developer released Sternbahn, a modular synth/groovebox for macOS built on the SunVox engine, now in free private beta (sternbahn.com).
- All 42 SunVox module types appear as cards on a canvas, connectable with audio cables; drag an LFO onto any control to modulate it, with a built-in sequencer for live performance.
- Native SwiftUI app, using only 10–12% of one CPU core while playing.
- Most of the Swift code was written by Claude Code: the patching UI, CoreAudio layer around the SunVox C engine, undo/redo, sequencer, a headless self-test suite, and the in-app guide — plus release pipeline (signing, notarization, Sparkle) and the website.
- The author contributed direction, sound design, and taste, testing on real hardware.
- Key optimization: live animations made SwiftUI redraw the whole window several times a second; moving scopes, meters, and modulated knobs to Core Animation cut playback usage to roughly a tenth of one core.
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