Rate
How fast the phaser sweeps.
- Turn up Faster swirling notches.
- Turn down Slow, psychedelic sweep.
Pedals / Phaser
Ninety Orange
Phaser · play-tested
seth — fish
seth@ninevolt:~$
Knobs
In the TUI each knob runs from low (left / 0%) to high (right / 100%). Start near noon, then nudge while you play.
Feedback
How resonant / peaky the phaser sounds.
- Turn up More dramatic, vocal, “whooshy” peaks.
- Turn down Milder phase shimmer.
Inspired by
MXR Phase 90 — four identical JFET all-pass stages (2N5952), one Speed knob on the original unit. Script Logo (1974) = no feedback resistor R28; Block Logo (1977+) adds R28 regen for sharper notches (ElectroSmash — Phase 90 analysis (PDF mirror)). LFO: Schmitt-trigger integrator → triangle wave modulates all four stages together. Output mixer ~50/50 dry/phased on hardware. Ninevolt display name Ninety Orange; Rate = Speed, Feedback = Script (low) ↔ Block (high). EVH, Blink-182, Offspring, Scorpions profiles.
Not a flanger or chorus — moving phase notches from cascaded APFs + dry mix (GeoFex — Phasers and flangers).
Signal path
| Step | What it does | |
|---|---|---|
| Triangle LFO Rate | Rate → 0.10–4.10 Hz; Schmitt-integrator-style triangle −1…+1. | |
| Log-swept corner | LFO sweeps JFET corner 58–800 Hz (ElectroSmash notch range); corner_to_apf_coeff() maps to digital APF coeffs ~0.97–0.99·Nyquist | Match |
| Feedback regen | 0 at Script (no R28); up to 0.85 at Block — R28 adds mid-hump + gain on hardware. | |
| 4× identical APF stages | First-order all-pass ladder; same swept cutoff on every stage (Phase 90 JFET topology). | |
| 50/50 dry/wet | Output mixer R8/R16 equal on hardware — cancellation at notch frequencies. | |
| Output | Classic four-stage swirl, clamped ±1. |
How we modeled it
Phase 90 path: input + regen → four identical swept APFs → 50/50 dry/wet mix. Rate sets LFO speed. Feedback 0 = Script (no R28); higher = Block resonance + gain. Hold chords — phasers need sustain; short plucks sound like EQ.
Phaser family: see PHASER_MOD_COMPARISON.md vs Purple Depth (Uni-Vibe) and Phase Lab (experimental).
Simplifications
- No Script/Block logo switch — continuous Feedback knob - Identical stage caps (Uni-Vibe uses staggered caps — see Purple Depth) - No input buffer / output mixer op-amp color - Fixed 50/50 mix (no Mix knob)