Spotify / streaming delivery mono-fold checklist: loudness + mono compatibility
Streaming masters often meter fine for loudness targets (Spotify, Apple Music, YouTube, Amazon) and still collapse on phone speakers, single-bud Bluetooth, and mono fold. That is usually Mid/Side imbalance, hard L/R beds, and width tools that were never auditioned in mono after loudness normalization, not a limiter problem alone. Fix mono audition of the delivery master, center critical low-mid energy, and simplify width first. Frequency-aware phase repair belongs only after residual L/R fights remain on stereo beds that must stay stereo before mono fold.
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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 meter, not a limiter, and not a substitute for mono audition of the streaming master. Polarity and timing first on multi-path sources; PHIXER after residual spectral fights on stereo beds.
What streaming mono-fold failure sounds like
- Loud and wide in cans, thin on phone. Normalization keeps level; mono fold removes Mid.
- Kick / bass / vocal chest disappear on single-bud BT. Hard L/R or Haas width hollows the center.
- Fine at target LUFS, broken on car and phone. Loudness compliance ≠ mono compatibility.
- Stereo imager after limiter wrecks fold. Width last in cans, cancellation first on mono.
- Same class of problem as master bus mono, YouTube mono, car / BT / phone, broadcast mono.
Fast mono audition (about 60 seconds)
- Solo the final streaming master (post-limiter / post-loudness tool). Flip a utility to mono.
- A/B stereo vs mono. Note what disappears: kick, bass, vocal chest, snare body, Mid guitars.
- Check correlation on the master. Negative dips on choruses are a red flag before upload.
- Spot-check a phone speaker or mono Bluetooth if available. Cans lie about fold.
Order of operations (before spectral phase rotation)
1. Mono-check the delivery master, not only the mix bus
Loudness tools and limiters can change balance. Audition the file (or bounce) you will upload. Related: master bus mono checklist.
2. Center critical low-mid energy
Kick, bass, and vocal chest should survive mono. If they live only as side energy or Haas width, phones and cars hollow them. Guides: car / BT / phone.
3. Simplify width tools before loudness
Imagers, Mid/Side wideners, and short-delay width after the limiter are classic mono killers. Prefer modest width earlier; prove mono after the final loudness pass.
4. Fix multi-path sources upstream
DI+mic, dual cab, OH+close, and parallel buses should be polarity- and delay-clean before the master. Guides: polarity vs phase, bass DI+amp.
5. Respect platform loudness without chasing peak loudness at all costs
Meet typical Integrated LUFS / True Peak guidance for your destinations, then re-check mono. Louder does not fix cancellation.
6. Only then audition residual L/R spectral fights
If a stereo bed must stay stereo and mono still hollows a band after the steps above, gentle frequency-aware phase rotation can help. Prove it with mono A/B, rotator bypassed vs engaged.
Path types and typical failure modes
| Path | Common mono failure | First fix |
|---|---|---|
| Master after imager + limiter | Kick/vocal thin on phone | Simplify width; mono A/B |
| Hard L/R guitars / synths | Huge in cans, gone on BT | Center critical Mid; reduce width |
| Haas / short-delay width | Hollow chest on fold | Remove Haas; Haas vs phase |
| Multi-path source into master | Body combs after loudness | Polarity + delay upstream |
| Loudness OK, fold not checked | Fine LUFS, broken mono | master bus mono / phone spot-check |
Streaming delivery checklist (to upload)
1. Confirm destination loudness / True Peak guidance
Spotify, Apple Music, YouTube, and others normalize. Aim for sensible Integrated LUFS and safe True Peak, then treat mono as a separate pass.
2. Mono-check the bounced master alone
Solo kick, bass, vocal, and Mid beds in mono. Note fights introduced by width or parallel paths.
3. Watch phone, car, and single-bud destinations
Most streams are heard on compromised mono-ish playback. Guides: car / BT / phone, YouTube mono.
4. Optional correlation + null habit before upload
Host-agnostic habit: DAW null-test + mono-check, correlation meters.
When PHIXER helps
- The material is already stereo and must stay stereo, not a mono master you fake-widened.
- Upstream polarity/delay, width simplification, and loudness pass are done, but mono still hollows a band.
- You can A/B mono with the plugin bypassed and hear clearer Mid without wrecking the image.
- You are not using it to "fix" Haas width, to replace a limiter, or to chase LUFS.
Decision table
| You notice… | First try | Why |
|---|---|---|
| Kick/vocal thin when imager opens | Pull width; mono A/B | Side-heavy Mid |
| Fine LUFS, hollow on phone | Mono master; center lows | Loudness ≠ mono |
| Haas guitars cancel chest | Remove Haas; simplify | Short-delay width |
| Stereo bed still cancels by band | PHIXER on that stereo bed | Residual spectral L/R fight |
| Mono master alone is dull | Tone / balance / EQ | Not an L/R repair job |
When NOT to use PHIXER here
- You have not mono-auditioned the bounced streaming master yet.
- The fix is obviously width simplification, centering low-mid, polarity upstream, or removing Haas.
- You want PHIXER to make the master louder, wider, or "more streaming-ready." Wrong job.
- The problem is True Peak overs or Integrated LUFS target, not L/R cancellation.
- See also when not to use PHIXER.
Quick path: Bounce streaming master → mono audition → center critical low-mid → simplify imagers/Haas → fix upstream multi-path polarity/delay → meet loudness / True Peak calmly → re-check mono → PHIXER only for leftover stereo cancellation on a stereo bed → upload.
Watch
- PHIXER tutorial + how it sounds (walkthrough with audio examples)