Duplicate a mono track across both left and right channels so it plays correctly on stereo-only equipment and platforms.
Mono to Stereo turns a single-channel recording into a two-channel file. Some players, editors and platforms need stereo; and a simulated stereo width can make a mono voice or instrument feel less cramped.
A mono recording contains no real left/right information, so this is honest simulation: Duplicate is the compatible choice, Haas uses the precedence effect with a short delay, and Wide uses all-pass decorrelation that folds back to the exact original in mono.
Duplicate copies the channel to left and right. Haas delays the right channel by 5–40 ms; our hearing fuses the delayed copy with the original but localises toward the leading side, creating width — but summing to mono creates comb-filter colouration. Wide runs a copy through three Schroeder all-pass filters (5.0, 8.3 and 12.7 ms) and sets L = x + a·ap(x), R = x − a·ap(x), so L+R equals 2x exactly — perfectly mono-compatible.
Deliver a mono voice in a stereo project.
Add width to a mono guitar or synth.
Satisfy tools that require stereo.
Widen a mono sample.
| Methods | Duplicate · Haas 5–40 ms · all-pass decorrelation |
|---|---|
| Mono compatibility | Wide: exact; Duplicate: exact; Haas: comb filtering |
No — stereo cannot be recovered from mono; this simulates width.
Yes, about twice as large at the same per-channel bitrate.
No — it duplicates the same signal on both channels, which fixes compatibility issues but doesn't add spatial width. For real stereo width you'd need a stereo recording or a dedicated widening effect.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
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