PHIXER for Multiband: crossover phase shifts and mono check
Multiband processors and crossovers can introduce band phase shifts. A 3-band crush or OTT-style split that feels huge in headphones can hollow one band on phone, Bluetooth, club PA mono, or livestream fold. Split-band gain reduction is not the same job as stereo phase repair. Crossover alignment, polarity, latency between bands, and true mono listen come first. Free PHIXER helps after residual L/R fights remain on a stereo bed you must keep stereo when the bands recombine.
Download PHIXER free YouTube tutorial YouTube intro
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 multiband compressor, not a crossover, not a stereo imager, and not a substitute for band gain structure or mono audition after bands recombine. Use it after hygiene, when residual spectral cancellation remains on a stereo bus you must keep stereo.
Why multiband / crossover moves phase
- Crossover split then recombine. Low, mid, and high bands look fine soloed; summed stereo hollows a band on mono fold when band filters or latency disagree. Polarity and timing first; spectral tools last.
- Multiband next to heavy bus / sidechain. A ducked bus into a multiband (or the reverse) shares the same mono scoop when stereo link or invert is wrong. Cousin: PHIXER for Bus Sidechain.
- Multiband next to a stereo imager. Width boost plus split-band crush can shift Side energy while bands recombine unevenly. Cousin: Stereo imager vs phase.
- Correlation as a quick tell. Meter near zero while headphones still feel huge? Check mono fold, then decide. Cousin: Correlation meter quick-read.
Fast mono fold check with PHIXER (about 60 seconds)
- Solo the multiband path (or the bus that carries it). Sum L+R with a monitor controller or utility. Do not mute one side to "hear the problem."
- A/B stereo vs mono across a sustained soft source and a kick hit. Note what disappears: kick body, bass weight, pad mid, vocal chest, hat air.
- Bypass the multiband briefly. If mono weight returns, the crossover / band depth / stereo-link settings may be the scoop, not free stereo. Then check Ø and a few samples of attack timing on L vs R.
- Confirm on a phone speaker, then again after sidechain duck, imagers, or stems join the bus. Re-check after bands recombine into the master.
Honest order of fixes (before spectral phase rotation)
1. True mono listen after bands recombine
Hard L+R sum with both ears open on the multiband output or stem sum. Habit: mono check workflow.
2. Crossover, band depth, and stereo link
If mono scoops only when one band is deep and release is long, fix the split first. Linked stereo multiband often behaves better than dual-mono bands that fight each other.
3. Polarity before more processing
Flip Ø on one bus path or one side while mono. Keep the flip that returns body. Guide: polarity invert vs continuous phase rotation.
4. Attack timing / band latency before spectral tools
Nudge a few samples or ms so transient peaks agree across L and R after bands recombine. Often enough on phones and club fold.
5. Bus / sidechain and imagers before spectral tools
Mute sidechain duck or mute the stereo imager briefly. If mono weight returns, fix those cousins first. Cousins: Bus Sidechain and Stereo imager vs phase.
6. Correlation hint before chasing continuous rotation
Read +1 / 0 / -1 in about a minute, then decide. Cousin: Correlation meter quick-read.
7. Skip when intentional thin mono is the point
Some Side-heavy multiband beds are meant to stay edge-only in mono. Honesty list: When not to use PHIXER.
8. Only then audition residual L/R spectral fights
If the stereo bed must stay stereo 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 YouTube intro.
Multiband / crossover setups and common mono failures
| Setup | Common mono failure | First fix |
|---|---|---|
| 3-4 band bus compressor | Mid band scoops on phone fold | Mono listen; check stereo link and Ø |
| OTT-style up/down split | Body dips when bands recombine | Band depth / crossover; polarity; timing |
| Dynamic EQ as multiband | Body thins when L/R already fight | True mono; Ø; less Side |
| Multiband after kick sidechain | Duck + split cancels on fold | Bus Sidechain |
| Multiband + stereo imager | Side boost cancels on fold | Imager vs phase |
| Multiband into master | Streaming / phone fold thins | Mono check master; less Side |
Related guides
- PHIXER for Bus Sidechain / heavy bus compression sidechain and stereo phase
- Stereo imager vs phase repair
- Correlation meter quick-read (+1 / 0 / -1 in 60 seconds)
- Polarity invert vs continuous phase rotation
- PHIXER for Stems / stem-bus phase
- When not to use PHIXER
- PHIXER for Vinyl Cut / lacquer mono prep (bass fold and phase)
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