PHIXER for Mid-Side: M/S decode and stereo width phase
Mid/Side encode and decode can feel huge in headphones: more Side, a wider bus, a stereo mic pair printed through an M/S matrix. On phone playback, Bluetooth, club PA mono, livestream fold, or a hall feed that goes LoRo, Mid thins and low-mid body dips while edges stay. Width tools push Side. Phase repair is a different job. Polarity and a few samples of timing come first. Free phase-repair helps after residual L/R fights remain on a stereo bed you must keep stereo. It is not a widener, not an M/S encoder, and it does not replace a true mono listen.
Download PHIXER free YouTube tutorial
PHIXER is free stereo phase-repair (VST3/CLAP/AU · Win/Mac/Linux) from Riverflux Audio. Frequency-aware phase rotation for leftover L/R fights on stereo material. It is not a Mid/Side width knob, not a polarity button, not a delay matcher, and not a substitute for mono audition after decode. Use it after hygiene, when residual spectral cancellation remains on a stereo bed you must keep stereo.
Three mid-side / width failure modes this page covers
- M/S decode after heavy Side boost. Encode → boost Side → decode sounds huge in cans. Phone and club fold scoop Mid body while edges stay.
- Stereo width / imager on a collapsing bed. Turning up width when L/R already fights makes mono worse. Cousin: PHIXER vs stereo imagers.
- M/S matrix on a stereo mic pair or OH / room bed. Pair or OH printed through Mid/Side can hollow the middle on fold. Cousins: Stereo Mic Pair and OH / Room.
Fast mid-side mono audition (about 60 seconds)
- Decode to L/R (or bypass the width stage) and sum L+R with a monitor controller or utility. Do not mute Side to "hear the problem."
- A/B stereo vs mono across a sustained note and a transient. Note what disappears: Mid body, attack, hall tone, or center image that was actually cancellation.
- Return Side level toward unity. Flip Ø on one decoded channel if body returns immediately. Then nudge a few samples of L vs R attack timing before chasing plugins.
- Confirm on a phone speaker, then again after bus EQ / compressor / reverb send. Re-check after mic-pair or OH / room beds join the bus.
Honest order of fixes (before spectral phase rotation)
1. True mono listen after decode
Hard L+R sum with Mid and Side both open in the decode path. Habit: mono check workflow.
2. Reduce Side before adding plugins
If mono scoops only when Side is loud, turn Side down. Width that cancels Mid is not free width.
3. Polarity before more processing
Flip Ø on one decoded channel while mono. Keep the flip that returns body. Guide: polarity vs phase.
4. Attack timing before spectral tools
Nudge a few samples or ms so transient peaks agree across L and R after decode. Often enough on phones and club fold.
5. Skip when intentional thin mono is the point
Some Side-heavy prints are meant to stay edge-only in fold. Honesty list: When not to use PHIXER. Comparison: Mid/Side vs phase repair.
6. Only then audition residual L/R spectral fights
If a stereo bed must stay stereo after M/S decode and fold still hollows a band after the steps above, gentle frequency-aware phase rotation can help. Prove it with mono A/B. Watch the YouTube tutorial and the mono demo.
M/S and width setups and common mono failures
| Setup | Common mono failure | First fix |
|---|---|---|
| Encode → Side boost → decode | Mid body dips; edges stay | Reduce Side; mono listen |
| Stereo imager / widener | Bass cancels harder in fold | Imager vs phase |
| M/S on XY / ORTF / A-B pair | Pair middle hollows on phone | Mic pair use-case |
| M/S on OH / room bed | Overhead body scoops under close mics | OH / room use-case |
| Master-bus width before delivery | Streaming / phone fold thins | Mono check master; less Side |
| Haas / shuffle width | Low end disappears in LoRo | Undo delay width; polarity / timing |
Mic pair and OH / room cousins (short version)
- Stereo mic pairs often meet M/S matrices in classical, jazz, and ensemble capture. Full write-up: PHIXER for Stereo Mic Pair.
- Overheads and rooms can pile more cancellation under a Side-boosted bed. Full write-up: PHIXER for OH / Room.
- Imagers and Mid/Side width are not phase repair. Comparisons: vs imagers · M/S vs phase.
- Polarity and attack timing still come first on every cousin. Spectral tools after residual L/R fights only.
When not to reach for PHIXER
- Side is simply too loud (turn Side down first).
- Wrong polarity on one decoded channel (flip Ø first).
- Obvious attack misalignment after decode (nudge first).
- You only need a mono-safe Mid print, not a stereo bed.
- Intentional Side-heavy texture that is meant to stay thin in mono.
- Honesty list: When not to use PHIXER.