Cross-modulation
VXN1 collapses what most synths spread across three distinct features — hard sync, FM/PM, and ring modulation — into one Cross-Mod Type selector with a single Cross-Mod Amount depth. The selected mode determines what Osc 2 does to Osc 1.
Modes
| Type | What it does |
|---|---|
| Off | Independent oscillators. Bit-identical to the no-cross-mod fast path. |
| Sync | Hard sync. Osc 1 is the slave; Osc 2 is the master. Sub-sample phase reset on every Osc 2 wrap, with polyBLEP residual for band-limiting. Sweep Osc 1’s pitch (typically via Pitch Env with Mod on) to get classic sync sweeps. |
| FM (PM) | Through-zero phase modulation. Osc 2’s output offsets Osc 1’s read phase. Labelled “FM” on the panel for familiarity — internally it is true phase modulation, which means pitch stays stable as the modulator’s DC level moves. |
| Ring | Diode-bridge ring modulator (Parker DAFx-11 model). The ring output replaces Osc 1’s mixer slot — Osc 1’s normal waveform is gone, replaced by the ring product. |
Amount
Cross-Mod Amount (0–4) maps to:
- Sync: ignored — sync is binary (mode selects whether sync happens; amount has no effect).
- PM/FM: phase deviation index. Higher values push Osc 1 into harsher inharmonic territory.
- Ring: ring depth (mixer level for the ring product).
A common starting point: PM at amount ~1.5 with Osc 2 a few semitones above Osc 1 gives a bell-like timbre.
Cross-Mod Sweep
There is no dedicated cross-mod sweep route. The classic sound — a wide, envelope-driven pitch swing on the modulator only — is built from two parts on the modulation panel:
- Pitch Env Mod switch (on the pitch route) — when on, the pitch envelope is routed only to the cross-mod modulator: Osc 1 under Sync, Osc 2 under PM / Ring / Off. Combine with the ±12 st Pitch Env Dep for the envelope swing.
- Wheel→X-Mod (on the mod-wheel routes) — ±48 st wide-pitch route from MIDI CC1, applies to both oscillators in parallel. Use it for hands-on sweeping.
Pair Pitch Env Mod + a high Pitch Env Dep with Cross-Mod Type = Sync, and you have the canonical sync-sweep lead. Same trick under PM gives a swept-index FM bell.
The Wheel→X-Mod route is not gated by Cross-Mod Type. With Off or Ring it acts as a normal pitch joystick (both oscillators move together); with Sync or PM it audibly drives the cross-mod timbre.
Aliasing notes
Cross-mod can fold significant high-frequency energy back into the audible band:
- Sync: polyBLEP-band-limited; safe at 1× oversample for most material.
- PM with non-sine modulator: aliasing is by design — many vintage PM sounds rely on it. The 4× / 8× oversampling settings are the escape hatch if a specific patch needs cleaning up.
- Ring: cleaner than PM, but ring of two saws will alias under 2×. Push oversampling for bright ring patches.
See Master for the global oversampling setting.
Parameters
| Parameter | Range | Default | Unit | Notes |
|---|---|---|---|---|
| Cross-Mod Type | Off / Sync / FM / Ring | Off | enum | Mode selector |
| Cross-Mod Amount | 0–4 | 0 | depth | Index for PM, mixer level for Ring; ignored by Sync |