FOLD Stereo to Mono

FOLD is a free AUv3 audio plugin and standalone app for controlling stereo width and collapsing your mix to mono — with a live phase correlation meter.

FOLD is a stereo width and mono fold-down utility for iOS. Use it as an AUv3 plugin in any compatible host.

FEATURES Width — Continuously variable stereo width from mono to full stereo. Drag the knob or tap to enter an exact value. Width changes are smoothed to avoid clicks.

Mono — One tap collapses your stereo signal to mono with a click-free ramp. Instantly check how your mix translates to a single speaker, earbuds, or phone.

Output Trim — ±12 dB gain stage after the width processing. Compensate for any perceived loudness shift when narrowing a wide mix.

Phase Correlation Meter — Real-time bar display with a numeric readout. Green means your signal is mono-compatible and safe. Amber indicates partial cancellation. Red flags phase cancellation issues that will cause problems on mono playback devices.

WORKS AS AN AUv3 PLUGIN

Load FOLD in Loopy Pro, GarageBand, AUM, Audiobus, Cubasis, n-Track, or any AU-compatible host on iPhone or iPad. The AUv3 extension exposes all parameters for host automation.

Free. No in-app purchases. No ads. No account required.