Mono Compatibility for AI Mixes
Most generated width leans on phase difference, and the mono sum exposes it.
Related
Switch to mono and the wide parts leave first
Sum the bus to mono and the generated wide pad drops back at once, the vocal survives, and the kick loses half its body. This is not a playback fault: where the two channels are out of phase, the sum cancels them. The wider the generated stereo image, the more obvious the cancellation.
Where the collapse comes from
Width can come from level difference, time difference or phase difference; only the first two survive the mono sum, while phase difference is eaten by it. Generative models often buy width with phase, especially in reverb and delay returns, and separated stems carry no guarantee of phase relationship. Low frequencies suffer most because their wavelengths are long, so a few milliseconds of delay is enough to cancel them. Comb filtering is what the mono sum turns into a hollow or metallic colour.
Checklist
- Listen to the whole track in mono and note which parts thin out or vanish
- Sum kick and bass alone; the low end should barely change
- Listen to left and right separately to find one-sided elements
- Halve the width plugin and the stereo reverb return, then listen again
- The vocal must not be covered by the backing in mono
- Read the correlation meter and treat sections that stay negative
- Check once more on a phone speaker to confirm the key elements remain
What cannot be repaired
Mono-ing the low end, narrowing the width and shortening delays recover most problems. But if the generated material is genuinely out of phase in a section, no adjustment brings it back, and a fresh generation is faster than fighting the phase. Mono compatibility is also not the only standard: some ambient music exists because of a wide field, and forcing it narrow costs the space. Judge in this order: keep the key elements first, the width second, and the air last.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Along the same line
Sources
- Bobby Owsinski, The Mixing Engineer’s Handbook 与 Bartlett, Practical Recording Techniques 中关于单声道求和与相位的章节。
- 生成式立体声的宽度来源，依据公开工具文档与听辨实践。