Riverflux Audio · Educational · Null test + polarity checklist
Null test + polarity checklist: when to reach for PHIXER
Practical stereo phase hygiene before you touch any continuous phase tool. Hear cancel on a true L+R null (or classic invert-null). Invert polarity first. Nudge timing second. Reach for free frequency-aware phase rotation only when residual L/R spectral fights remain on a path that must stay stereo.
Download PHIXER free YouTube tutorial YouTube intro
PHIXER is free stereo phase-repair (VST3/CLAP/AU · Win/Mac/Linux) from Riverflux Audio. Continuous, frequency-aware phase rotation for leftover L/R fights. It is not a null-test meter, not a 180° polarity button, not a sample-align delay, and not an InPhase-class alignment suite. Use this checklist to decide whether you need it at all.
Printable checklist (about 2 minutes)
- True mono / null listen. Sum L+R (or invert one side into the other). Do not mute one channel and call it a mono check.
- Name what disappears. Bass body, kick punch, snare crack, vocal center, or a whole stereo bed.
- Polarity invert (Ø / 180°) first. Flip one path. Keep the flip that returns weight on the null. If mono is fixed, stop.
- Attack timing second. Nudge a few samples or ms so transients agree. Re-null after the nudge.
- Correlation glance. Needle toward -1 or 0 on the hollow moments confirms anti-correlation. Ears still win.
- Phone / club fold re-check. Many listeners only hear the fold. Re-test after limiter or encode.
- Reach for PHIXER only if the stereo path must stay stereo, invert + timing helped only part of the spectrum, and a band still cancels on fold.
- Prove any rotation. Mono A/B before and after. If the null did not improve, undo.
Polarity invert vs continuous phase rotation
| Tool | What it does | Reach for it when |
|---|---|---|
| Polarity invert (Ø) | Flips the whole waveform 180° | One path is simply inverted vs another (DI+cab, dual mic, bus copy) |
| Sample / ms align | Slides time so attacks meet | Late hit or mic distance delay is the scoop |
| Continuous phase rotation (PHIXER) | Rotates phase across frequency on a stereo bed | Leftover L/R spectral cancel after Ø and timing; bed must stay stereo |
| InPhase-class aligners | Delay / correlation alignment suites (paid) | Track-to-track time alignment jobs. Different tool class: PHIXER vs Waves InPhase |
When to reach for PHIXER (and when not)
Reach for it
- Stereo sample, stem, or DJ edit that still hollows a band in mono after Ø and timing.
- Remix contest packs or club edits where kick/bass vanish on mono club systems. Cousins: DJ edit / club mono fold · remix contest stem phase-check.
- You need continuous Amount / From / To control, not another 180 flip.
Skip it
- A single Ø flip already restores mono weight.
- The fix is delay / Haas / time-align, not spectral phase.
- You can print a mono-safe center and do not need the stereo bed.
- Honest limits: When not to use PHIXER (delay, mono, Haas).
Fast hear-cancel workflow
- Solo the stereo bed. Play a sustained soft source and a transient hit.
- Sum L+R. Optionally classic-null by inverting one channel into the other.
- Flip Ø on one path. Keep the flip that returns body. Stop if done.
- Nudge timing a few samples. Re-null and re-check on a phone speaker.
- Only then audition PHIXER on residual spectral fights. Prove with mono A/B.
- Watch: tutorial · intro.
Related guides
- Polarity invert vs continuous phase rotation
- Phase-checking DJ edits and club edits before release
- Phase-check remix contest stems and DJ edit packs
- PHIXER vs Waves InPhase (different jobs)
- Mid/side processing vs stereo phase rotation for mono compatibility
- Correlation meter quick-read (+1 / 0 / -1)
- When not to use PHIXER
- Hub
- Product
- Gumroad download
- YouTube tutorial · YouTube intro