PHIXER for Live FOH: foldback, stream phase, and honest mono on the matrix
IEMs and booth monitors can feel huge while the stereo matrix for stream, broadcast, or phone clips goes hollow. Open mics, wedges, and dual-path kits create near-copies that cancel when summed. That is live dual-path physics, not a broken console. Mono check the matrix before you print. Free phase-repair helps after polarity and timing. It is not a widener, and it does not replace a true mono listen on the stream bus.
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 live limiter, not a time-aligner, not a stereo widener, and not a substitute for polarity, delay matching, or a real mono check on the FOH / stream matrix. Use it after hygiene, when residual spectral cancellation remains on a stereo bed you must keep stereo.
Three live FOH failure modes this page covers
- FOH / foldback / stream phase. Matrix sounds fine in IEMs; stream and phone clips thin. Full checklist: Live FOH / foldback / stream phase.
- Club / DJ PA cousin. Same mono-fold story on dancefloor PA and USB sticks. Cousin guide: PHIXER for DJs.
- Streamers / OBS cousin. Dual-PC and Discord Stage folds that cancel viewer mono. Cousin guide: PHIXER for Streamers.
Fast live matrix mono audition (about 60 seconds)
- Sum L+R on the stream / broadcast / matrix bus (or monitor controller mono). Listen to kick body, vocal mid, and room tails.
- A/B stereo vs mono. Note what disappears: kick thump, vocal chest, bass fundamental.
- Mute open ambient / OH / wedge-bleed paths briefly. Note which path thins the fold.
- Confirm on a phone speaker or single earbud path, then again after any bus FX / limiter pass, not only before cleanup.
Honest order of fixes (before spectral phase rotation)
1. True mono listen on the matrix / stream bus
Hard L+R sum or monitor mono. Habit: Live FOH / foldback / stream phase and mono check workflow.
2. Polarity if a path flips
Kick in/out, snare top/bottom, dual guitar cabs, vocal + ambient. Flip Ø when body returns. Guide: polarity vs phase.
3. Timing / delay-align before spectral tools
Console delay or DAW nudge on dual-path kits and DI+amp. Spectral rotation is not a substitute for a few ms of delay.
4. Prefer one hero path for critical lows
Keep critical low-mid correlated on the matrix. Put width in sides that survive fold. Related: DJ / club PA and streamers / OBS.
5. Only then audition residual L/R spectral fights
If a stereo matrix 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 mono demo.
Live FOH / foldback / stream path types
| Setup | Common mono failure | First fix |
|---|---|---|
| FOH stereo matrix only | Fine in IEMs, thin on stream | True mono listen before print |
| Close mics + OH / ambient | Body cancels on sum | Polarity; align; mute weaker path |
| Wedge bleed into open mics | Midrange fights itself | Reduce wedge; see FOH checklist |
| FOH dump into OBS / stream | Room-flattering stereo hollows on phones | Dedicated stream bus; streamers guide |
| Club / festival PA fold | Wide FX under kick gone | DJ / club PA guide |
| Phone / Instagram clip of the gig | Huge in booth, gone on phone | Phone speaker check before delivery |
DJ and streamer cousins (short version)
- Club PA and USB sticks have the same mono-fold shape as a live matrix dump.
- OBS / Twitch / YouTube Live viewer fold cancels the same way when headphones hide L/R fights.
- Polarity and timing still come first. Spectral tools after residual L/R fights only.
- Full write-ups: PHIXER for DJs · PHIXER for Streamers.
When free PHIXER belongs in a live FOH toolkit
- The material is already stereo and must stay stereo (matrix bed, stereo stream print), not a mono PA dump you fake-widened.
- Polarity, timing, and mono listen are cleaned up, but fold still hollows a band of the spectrum.
- You can A/B mono with the plugin bypassed and hear clearer body without wrecking the image.
- You are building a mono habit on the stream bus, not using PHIXER to paper over three open dual paths.
- Budget is zero: free download on Gumroad (Win/Mac/Linux · VST3/CLAP/AU).
Decision table
| You notice… | First try | Why |
|---|---|---|
| Stream thins when mono | Mute ambient/OH; polarity | Anti-correlated dual path |
| Close + OH cancel body | Align a few ms | Timing before spectral tools |
| Stereo matrix still cancels by band | PHIXER on that stereo print | Residual spectral L/R fight |
| Wedge bleed dominates | Reduce wedge / gate | Not an L/R repair job first |
| Club PA hollows the same way | DJ checklist | Same mono-fold physics |
| You want more loudness | Limiter / gain staging | PHIXER is not a loudness tool |
When NOT to use PHIXER here
- You have not mono-auditioned the matrix / stream bus or a phone speaker yet.
- The fix is obviously quieter ambient path, polarity, or a few ms of delay.
- You want PHIXER to fix feedback, replace a time-aligner, or widen a mono PA dump. Wrong job.
- The path is mono and the print problem is level or tone.
- Full list: when not to use PHIXER.
Quick path: Matrix mono listen → mute fighting ambient / OH → polarity if a path flips → align dual-path kits → mono again after bus FX → phone check → PHIXER only for leftover stereo cancellation on a bed you must keep stereo → confirm again in mono. Cousins: DJs · Streamers · core FOH: waxen-badge-qea5.