Chorus Module — BBD Stereo Chorus

Juno-inspired BBD (Bucket Brigade Device) stereo chorus with two delay lines, each modulated by a triangle-wave LFO. Supports three modes: I, II, and I+II.

Files

static/js/synth/modules/chorus.js

Signal Flow

                    ┌──→ dryGain ──┐
                    │               │
input ──→ split ────┼──→ delay1 ──→ wet1 ──┼──→ mix ──→ output
                    │   ↑ LFO1              │
                    │                       │
                    └──→ delay2 ──→ wet2 ──┘
                        ↑ LFO2

• Mode I: delay1 only (LFO1 at chorusRate, depth chorusDepth)
• Mode II: delay2 only (LFO2 at chorusRate × 2.5)
• Mode I+II: both delays active
• Off: dry signal passes at unity, wet gains set to 0

Parameters

Param	Range	Default	Description
chorusMode	off/I/II/I+II	off	Chorus mode selector
chorusRate	0.1–5 Hz	0.7 Hz	LFO rate for delay time modulation
chorusDepth	0–1	0.5	Modulation depth (scales LFO gain to delayTime)

Exports

Export	Signature	Purpose
paramDefs	—	Parameter definitions for UI generation
build	(ctx, params, input, dur)	Create two delay lines with LFOs, dry/wet sum
update	(nodes, params)	Update mode, rate, depth

Build Details

• Two DelayNodes (max 50 ms), initial delay times 15 ms / 22 ms
• Two triangle-wave OscillatorNodes started immediately, run continuously
• LFO outputs connect through GainNodes to delayTime AudioParams
• Dry/wet gains: mode-off = 1/0, mode-on = 0.5/0.5
• Mode II LFO runs at rate × 2.5 for a wider stereo effect