PHIXER for Mastering: master bus mono checklist, streaming loudness + mono, and honest limits
A master can hit platform LUFS and still hollow on phone, club mono, Bluetooth, and some streaming play paths. That is fold physics and residual L/R fights, not a broken limiter. Mono check before send-to-mastering. Loudness OK is not mono OK. Free phase-repair helps after polarity and timing. It is not a loudness tool, 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 loudness processor, not a limiter, not a stereo widener, and not a substitute for polarity, timing, or a real mono check. Use it after hygiene, when residual spectral cancellation remains on a stereo master bus, stem stack, or print you must keep stereo.
Three mastering failure modes this page covers
- Master bus mono checklist. Stereo width, M/S tricks, and parallel paths that sound huge in the suite can cancel when you sum L+R before delivery. Full checklist: Master bus mono checklist.
- Streaming loudness + mono. Hitting Spotify / Apple / YouTube LUFS targets does not guarantee mono-safe low-mids. Platform normalization and phone speakers expose anti-correlated energy headphones hid. Guide: Spotify / streaming loudness + mono compatibility.
- When not to use. Spectral phase rotation is the wrong fix for a dull mono vocal, a polarity flip, or a loudness miss. Honesty list: when not to use PHIXER.
Fast master-bus mono audition (about 60 seconds)
- Sum L+R on the master (or your monitor controller mono). Listen to kick, bass, vocal, and reverb tails.
- A/B stereo vs mono. Note what disappears: chest, kick body, vocal mid, guitar body.
- Mute stereo wideners / M/S width / hard L/R FX briefly. Note which path thins the fold.
- Confirm on a phone speaker or Bluetooth-like mono path, then again after your limiter / LUFS pass, not only before loudness.
Honest order of fixes (before spectral phase rotation)
1. True mono listen on the master
Hard L+R sum or monitor mono. Habit: mono check workflow and master bus mono checklist.
2. Polarity if a path flips
Interfaces, stems, and some DSP invert. Flip Ø when body returns immediately. Guide: when not to use PHIXER (polarity first).
3. Timing / align before spectral tools
Layered kicks, dual-mic guitars, and printed parallel buses need sample-accurate alignment first. Spectral rotation is not a substitute for a few ms of delay.
4. Prefer mono-safe low-mid energy
Keep critical low-mid correlated. Put width in sides that survive fold. Related: streaming loudness + mono.
5. Only then audition residual L/R spectral fights
If a stereo master print, stem stack, or bus 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.
Mastering path types
| Setup | Common mono failure | First fix |
|---|---|---|
| Master bus before send | Fine in suite, thin in mono | True mono listen; mute fighting width |
| After limiter / LUFS pass | LUFS OK, phone hollow | Mono after loudness; see streaming + mono |
| M/S or stereo widener on master | Center thins on fold | Reduce Side; check low-mid correlation |
| Printed stem stack into master | Session OK, print hollow | Audition stems alone; stems guide |
| Vinyl / club mono check | Bass cancels on sum | Correlate lows; polarity; timing |
| Phone / Bluetooth / car | Huge in nearfields, gone on phone | Phone speaker check before delivery |
Streaming loudness + mono (short version)
- Platforms normalize integrated loudness. Chasing louder LUFS does not fix mono cancellation.
- Check mono after your limiter, not only before. Limiting can change how width and low-mids sit.
- Phone speakers and many earbuds are effectively mono or near-mono. That is the real delivery path for many listeners.
- Full write-up: Spotify / streaming loudness + mono compatibility.
When free PHIXER belongs in a mastering toolkit
- The material is already stereo and must stay stereo (master print, stem stack, stereo bus), not a mono vocal 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 master, not using PHIXER to paper over three open wideners.
- Budget is zero: free download on Gumroad (Win/Mac/Linux · VST3/CLAP/AU).
Decision table
| You notice… | First try | Why |
|---|---|---|
| Master thins when mono | Mute width; polarity | Anti-correlated low-mid |
| LUFS OK, phone hollow | Mono after limiter | Loudness ≠ mono |
| Kick / bass cancel on sum | Align; correlate lows | Timing before spectral tools |
| Stereo print still cancels by band | PHIXER on that stereo print | Residual spectral L/R fight |
| Vocal alone is dull | Gain / EQ / take choice | Not an L/R repair job |
| 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 master or a phone speaker yet.
- The fix is obviously quieter stereo width, polarity, or a few ms of delay.
- You want PHIXER to make the master louder, wider, or to replace a limiter. Wrong job.
- The path is mono and the print problem is level or tone.
- Full list: when not to use PHIXER.
Quick path: Master mono listen → mute fighting width → polarity if a path flips → align layered / parallel paths → mono again after limiter / LUFS → phone check → PHIXER only for leftover stereo cancellation on a print you must keep stereo → confirm again in mono.