feat: add Filter FM (Devilfish mod) - #35
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- Add DiodeLadderFilter based on Will Pirkle's analysis - Implement 4-pole diode ladder with TB-303 octave mode option - Add FilterType enum (TeeBee, Diode, DiodeOctave) - Integrate filter selection into Open303 synth engine - Include passband gain compensation and input drive 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Add three distinct nonlinearity stages modeling real diode behavior: 1. diodeShape() - asymmetric input saturation (exp on positive, linear negative) 2. fbShape() - feedback path saturation for resonance collapse/chirp 3. stageNL() - per-stage cubic nonlinearity for grit under drive - Add DC blocker to prevent low-frequency buildup - Remove chowdsp math_approx dependency (use std::exp directly) - Add detailed signal flow documentation in header 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- AC-coupled input signal modulates filter cutoff at audio rate - One-pole HPF (~20Hz) removes DC before modulation - Creates FM sidebands, talking/screaming character with resonance - New setFilterFmDepth() API (0-100%) Based on Devilfish mod: "Filter FM uses the output of the VCA, AC coupled into the filter cutoff frequency" 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Hey @dfl I'd love to get in touch with you but I can not afford LinkedIn Premium. Can you perhaps join the midilab Discord? :) <3 https://discord.gg/NWSvqJj9K |
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Summary
setFilterFmDepth()API (0-100%)Based on Devilfish mod: "Filter FM uses the output of the VCA, AC coupled into the filter cutoff frequency"
Dependencies
🤖 Generated with Claude Code