Master bus mono checklist (before send-to-mastering)
The last 10 minutes on the mix bus catch more delivery failures than another stereo widener. Flip mono, watch correlation, mute suspicious FX, then decide if any residual spectral fight remains.
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PHIXER is free stereo phase-repair (VST3/CLAP/AU · Win/Mac/Linux). Frequency-aware phase rotation for leftover L/R fights. It is not a mastering chain, not a widener, and not a substitute for mono-checking the bounce.
1. Mono fold for 30–60 seconds
Flip the mix to mono on a dense chorus, drop, or dialogue bed. Note hollow vocals, thin kick, missing bass. Those are usually arrangement or path fights, not “needs more width.”
2. Correlation glance
- Watch a correlation / goniometer on the master during the loudest sections.
- Sustained negative dips mean fold risk on phones, clubs, and LoRo paths.
- Do not chase a perfect +1. Catch collapses where the song sells.
Deep dive: correlation & phase meters.
3. Solo suspicious stereo FX
Mute one at a time in mono
Ping-pong delays, Haas doubles, imagers, mid/side wideners. Prefer redesign (HPF wet, less width, mono delay) over stacking more stereo processors. See delay throws vs mono and Haas vs phase.
4. Hygiene leftovers
- Dual-mic paths: polarity and timing done? (drums, DI+amp, vocals)
- Parallel buses: polarity matched before saturation stacks (parallel bus guide)
5. Residual spectral fights only
If a stereo print still cancels by band after the above, try frequency-aware phase rotation on that stem or bus, then mono-check again. Wrong first tool for un-checked Haas or dense ping-pong.
When NOT to use PHIXER on the master
- You have not mono-checked dry+FX yet.
- A polarity or timing fix on a source already restores body.
- You want PHIXER as a “mastering widener.” Wrong job.
- The mix is already mono-safe and you are chasing louder.
Quick path: Mono fold → correlation glance → mute stereo FX offenders → source hygiene → PHIXER only for residual band fights → mono-check the bounce again.