DAW null-test and mono-check workflow (with PHIXER in the right slot)
A short, repeatable habit for any DAW: mono-check dual paths, use null tests honestly, fix polarity and timing first, then decide if frequency-aware phase repair earns a place.
Download PHIXER free PHIXER hub
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 widener, not a time-aligner, and not a substitute for polarity or delay matching.
What this workflow is for
You want a repeatable DAW habit: prove whether a stereo clip cancels in mono, fix polarity and timing first, then decide if frequency-aware phase repair earns a slot. This is host-agnostic (Ableton, Reaper, Logic, Studio One, Bitwig). Names differ; the order does not.
Pair with mono check before/after and correlation and phase meters.
Null tests vs mono checks (do not confuse them)
- Mono check: sum L+R (or flip a mono button) and listen. Ask: does body disappear?
- Null / cancel test: invert polarity on a duplicate path and sum to silence (or near-silence) to prove two signals are identical, or to isolate a processor's change.
- Where null tests lie: dither, adaptive processors, lookahead, and nonlinear FX never null cleanly. That does not mean your mono fold is fine.
Setup once (any DAW)
- Create a Mono Check utility: mono button on the master, or a mid/side utility with Side muted, or a dedicated mono fold plugin.
- Optional: put a correlation / goniometer on the master or on buses you care about.
- Keep a keyboard shortcut or scene that toggles mono so you actually use it.
Workflow A: dual-path capture (DI+mic, top/bottom, spots+mains)
- Solo the pair. Enable mono check.
- Flip polarity on one path. Keep the fuller mono.
- Nudge timing to the shared attack.
- Role-split EQ if both share the same lump.
- If a stereo bus still band-cancels, try PHIXER on that stereo bus, then mono-check again.
Workflow B: printed stereo stem you cannot re-mic
- Mono-check the stem alone.
- If it hollows, try PHIXER on the stereo file (not on a mono track).
- A/B in mono and in stereo. Keep only if mono improves without wrecking the stereo image you need.
- If mono still fails, the stem may need arrangement or a different take. See when not to use PHIXER.
Workflow C: prove a processor change (honest null)
- Duplicate the track. Invert polarity on the duplicate.
- With identical settings and no adaptive FX, you should get near silence.
- Engage PHIXER (or any FX) on one copy only. What remains is the difference.
- Use that to hear what changed, then still mono-check the kept version. Difference ≠ mono-safe.
Decision table
| Result | Next step |
|---|---|
| Mono check thins; Ø restores body | Keep polarity; stop if enough |
| Mono check thins; delay aligns attacks | Keep timing; stop if enough |
| Stereo bus still band-cancels after hygiene | Try PHIXER; re-check mono + stereo |
| Null test never silences with adaptive FX | Expected; rely on mono check + ears |
| Mono source sounds thin | Not a PHIXER job |
Common mistakes
- Widening before mono-check.
- Running PHIXER on mono tracks.
- Trusting a green correlation meter without listening on phone/mono.
- Assuming a failed null means the mix is broken (adaptive FX).
- Skipping polarity/timing because a phase plugin exists.
Habit: mono-check every dual-path and every stereo stem before creative width. Polarity → timing → role-split → residual stereo phase repair → width last.
Related reading
- Mono check before/after
- Correlation & phase meters
- Polarity invert vs phase rotation
- Phase repair vs time-align
- Product · Hub
Get the free fixer
PHIXER is free stereo phase-repair from Riverflux Audio (VST3/CLAP/AU · Win/Mac/Linux). Slot it after polarity and timing in the workflows above.