When the Spec Becomes Code: Building a Norns Instrument with AI

video upload by Lesjamusic

"Building PolyNexus: A Complete Norns Instrument, using Claude AI

I used to struggle with "vibe coding" - throwing prompts at AI and hoping for working software. Then I discovered the article "When the Spec Becomes the Code," and everything changed.

Spec-driven development (SDD) transformed my workflow. Instead of generating code through endless prompts, I focus on creating clear specifications first. The spec becomes the blueprint, and Claude AI helps compile it into working code.

PolyNexus is the result of this approach - a complete generative polyphonic instrument for Monome Norns that evolved far beyond my initial vision. What started as a chord sequencer grew ambitious: I built PolyVoice, a custom 6-voice synthesizer engine in SuperCollider, based on three Plaits oscillator models with wavefolding, sample rate reduction, and comprehensive modulation.

The best part? Spec-driven development gave me the confidence to tackle SuperCollider synthesis, something I wouldn't have attempted with traditional "vibe coding."

🎹 PolyNexus Features:

PolyVoice Synthesis Engine: • Custom 6-voice polyphonic SuperCollider engine • Three Plaits-inspired oscillator models (morph, waveshaping, wavetable) • Wavefolding for harmonic complexity • Sample rate reduction for lo-fi textures • Independent LFOs and envelope control per voice

Generative Sequencer: • 16-chord harmonic palette (monome Grid row 1) • Probabilistic note retriggering engine • Random chord sequencer for compositional surprises • Bass and sub-bass sequencer for rhythmic foundation • Real-time playable notes (Grid row 5)

Analog-Style Effects Chain: • Tape character: flutter, wow, saturation, tape noise • Tape-style delay with feedback and rate control • Multi-mode filtering for tone shaping

🔗 Resources: • Jean Bovet: "When the Spec Becomes the Code" - / when-the-spec-becomes-the-code • PolyNexus (coming soon to lines community) • monome Norns - https://monome.org • Mutable Instruments Plaits • SuperCollider synthesis language

⏱️ Timeline:
0:00 - Introduction: The Struggle with Vibe Coding
01:51 - Discovery: Spec-Driven Development
04:33 - What is PolyNexus?
12:37 - Live Performance

Want to try spec-driven development? Start by describing what you want to build in clear, detailed language. Iterate on the specification until it's crystal clear. Then let AI help compile it into code. You'll be amazed at what becomes possible."