Ruina Module — Stereo Distortion Processor

Three distortion algorithms designed for the Ruina Versio character: hard clipping with asymmetric wavefolding, gated distortion (Ruina v2), and multiband compression with bit crushing. Stereo width parameter applies different drive/fold amounts to each channel.

Available as a send effect in the sequencer (Ruina card in the master collapsible section, Snd tab per-sound send fader).

Signal Flow

input (mono send sum)
  → ChannelSplitter(2)
    ├→ L: driveGain → clipWaveshaper → foldGain → foldWaveshaper → gateWaveshaper → crushWaveshaper → levelGain
    └→ R: driveGain(×width) → clipWaveshaper(×width) → foldGain(×width) → foldWaveshaper(×width) → gateWaveshaper(×width) → crushWaveshaper → levelGain
  → ChannelMerger(2) → wetGain → output
          dry path ──────────────→ dryGain → output

Parameters

Param	Range	Default	Description
`ruinaMode`	ruina/ruina2/comp	ruina	Distortion algorithm
`ruinaDrive`	0–1	0.5	Input gain before clipping
`ruinaFold`	0–1	0	Wavefolding depth
`ruinaCrush`	0–1	0	Bit reduction (4–16 bits)
`ruinaMix`	0–1	0.5	Wet/dry blend
`ruinaWidth`	0–1	0.5	Stereo separation (L/R channel difference)

Modes

Ruina

Asymmetric hard clipping using tanh with different positive/negative scaling (×0.7 vs ×1.3). The fold parameter adds sine-based wavefolding for aggressive, metallic textures. drive controls input gain before the clip stage.

Ruina v2

Same clip + fold as Ruina, but with a noise gate that drops the signal to zero when the input amplitude is below drive × 0.3. Creates the signature gated, chopped sound.

Comp

OTT-style compression (split into 3 bands, each band compressed) combined with bit crushing. fold acts as compression ratio makeup gain. crush sets bit depth via quantised waveshaper curve.

Stereo Width

L channel uses drive × (1 − width/3) and fold × (1 − width/3). R channel uses drive × (1 + width/3) and fold × (1 + width/3).

At width = 0 both channels are identical (mono). At width = 1, L gets ~67% and R gets ~133% of the nominal parameter values.

Curve Generation

Curve	Function	Description
`buildHardClipCurve(drive)`	Asymmetric tanh	Positive clips softer than negative
`buildFoldCurve(amount)`	`sin(x × π × (1 + amount × 5))` scaled	Sine-based wavefolder
`buildCrushCurve(bits)`	Quantised levels `2^(4 + bits × 12)`	Bit crusher
`buildGateCurve(threshold)`	Zero below threshold, pass above	Noise gate

Exports

Export	Signature	Purpose
`paramDefs`	—	UI param definitions (6 params, `ruinaMode` as pills)
`build`	`(ctx, engine)`	Create stereo processor chain, returns `{ input, output, nodes }`
`update`	`(nodes, engine)`	Update curves and gains from engine params

Integration

As sequencer send FX

The Ruina is wired in ensureMasterBus alongside reverb:

engine._ruinaInput = ac.createGain()
engine._ruinaNode = ruinaMod.build(ac, engine)
engine._ruinaInput → engine._ruinaNode.input
engine._ruinaNode.output → ChannelSplitter(2) → _limSumL / _limSumR

Per-sound send level is controlled via sound.sends.ruina (set in Snd tab).

As a processor module

Can be added to any engine's modules array, but designed primarily as a master send FX.

Files

File	Purpose
`modules/ruina.js`	Module implementation (193 lines)
`sequencer-audio.js`	Master bus wiring (`ensureMasterBus`)
`sequencer-ui.js`	Master section Ruina card + Snd tab slider
`sequencer.js`	`_playNote` ruina send routing