PHIXER for Amp + DI: amp and DI blend phase for guitar and bass
Amp plus DI blends can feel huge in headphones: DI clarity next to cab grit, or a reamp stack with a dry DI. On phone playback, Bluetooth, club PA mono, or livestream fold, low-mid body thins and note attack softens while highs stay. Polarity and a few samples of timing come first. Free phase-repair helps after residual L/R fights remain on a stereo amp + DI bed you must keep stereo. It is not a cab IR, not a DI reamp, and it does not replace a true mono listen on the bus.
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 polarity button, not a delay matcher, not a widener, and not a substitute for mic placement. Use it after hygiene, when residual spectral cancellation remains on a stereo bed you must keep stereo.
Three amp + DI failure modes this page covers
- Guitar amp + DI / reamp blend. Fine in cans; thin chest of chords on phone or club fold. Cousin: PHIXER for Guitar Cabs.
- Bass DI + amp / cab IR dual path. Fundamental dips when DI and amp grit sum. Cousin: PHIXER for Bass DI.
- Room / OH bleed under an amp + DI stack. Kit or room beds fight the same fold shape. Cousin: PHIXER for OH / Room.
Fast amp + DI mono audition (about 60 seconds)
- Sum L+R on the guitar or bass bus (or monitor controller mono) with amp and DI both open.
- A/B stereo vs mono across a sustained note and a transient. Note what disappears: low-mid body, pick attack, cab thump, or grit that was actually cancellation.
- Mute the amp (or the DI) briefly. Flip Ø on the amp path (or the DI). Keep the flip that returns body without killing the blend.
- Nudge a few samples of amp vs DI attack timing before chasing plugins. Confirm on a phone speaker, then again after bus EQ / compressor / saturation.
Honest order of fixes (before spectral phase rotation)
1. True mono listen on the full amp + DI blend
Hard L+R sum or monitor mono with both paths open. Habit: mono check workflow.
2. One hero for body
Prefer DI (or one cab mic) for weight and let the other path add grit or air without fighting Mid on every note.
3. Polarity before more processing
Flip Ø on the amp (or the DI) while mono. Keep the flip that returns body. Guide: polarity vs phase.
4. Attack timing before spectral tools
Nudge a few samples or ms so transient peaks agree across amp and DI. Often enough on its own on phones and clubs.
5. Skip when intentional thin grit is the point
Some mixes deliberately thin in mono for DI-led or amp-led textures. Honesty list: When not to use PHIXER.
6. Only then audition residual L/R spectral fights
If a stereo amp + DI bed 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.
Amp + DI path types
| Setup | Common mono failure | First fix |
|---|---|---|
| Guitar amp mic + DI | Chord body dips when summed | Polarity + timing; mono listen |
| Guitar dual cab + DI | Grit stays, low-mid hollows | Guitar cabs use-case |
| Bass DI + amp / cab mic | Fundamental scoops on phone fold | Bass DI use-case |
| Bass DI + cab IR / amp-sim | Impulse latency vs dry DI cancels mid-bass | One hero; flip Ø; nudge timing |
| Reamp wet + dry DI | Attack softens on club mono | Polarity on wet; mono A/B |
| Amp + DI under OH / rooms | Bleed + blend both hollow | OH / room use-case |
Guitar cabs, bass DI, and OH cousins (short version)
- Dual guitar cabs and multi-mic cabs hollow the same way amp + DI fights Mid. Full write-up: PHIXER for Guitar Cabs.
- Bass DI + amp dual path is the low-end cousin of the same blend. Full write-up: PHIXER for Bass DI.
- Overheads and rooms can pile more cancellation under an amp + DI stack. Full write-up: PHIXER for OH / Room.
- Polarity and attack timing still come first on every cousin. Spectral tools after residual L/R fights only.
When not to reach for PHIXER
- Wrong polarity on the amp or DI (flip Ø first).
- Obvious attack misalignment between amp and DI (nudge first).
- You only need one hero path or a mono-safe print of the blend.
- Intentional thin amp or DI-led texture that is meant to stay thin in mono.
- Honesty list: When not to use PHIXER.