Upright bass / double bass DI + mic + amp dual-path phase: why fundamentals cancel on mono fold
DI or pickup plus bridge/body mic (and optional amp) feels weighty in the booth and on stage wedges. On studio mono fold or livestream, fundamental, body, and pizz attack often thin or cancel against secondary paths that carry the same note a few milliseconds later. That is usually polarity and arrival time between DI and mic/amp, plus a stereo bed that was never folded before send. Fix polarity and small delays first. Frequency-aware phase repair belongs only after residual L/R fights remain on stereo beds before mono fold. Distinct from electric bass DI + amp/cab: this page is upright / double bass acoustic dual-path hygiene.
Download PHIXER free Learn more 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 compressor, not a widener, and not a substitute for mic placement or mono audition of the stream or mix bus. Polarity and timing first; PHIXER after residual spectral fights.
What upright / double bass DI + mic + amp phase failure sounds like
- Fundamental huge in headphones, thin on phones. DI (or pickup) and bridge / body mic share the same note a few ms apart.
- Amp or cab grit cancels body on livestream. Mic + DI + amp stack notches low Mid when the platform folds.
- Pizz attack present in booth, soft on phone. Dual-path acoustic + DI without polarity and timing hygiene.
- Bow scrape harsh after fold. Stereo board or hard L/R beds collapse Mid while edges remain.
- Fine on stage wedges, broken for remote viewers. Same destinations as electric bass DI + amp (cousin workflow, different instrument), live FOH, OBS livestream.
Distinct from electric bass DI + amp
Electric bass dual-path (DI + reamp / cab) is covered at alpine-lantern-hqbk. This page is upright / double bass: acoustic body and bridge mic energy, optional piezo or magnetic pickup DI, optional amp for grit or stage, and room / OH for jazz and classical capture. Same polarity-and-timing first rule. Different resonance, bow noise, and mic placement traps.
Fast mono audition (about 60 seconds)
- Solo the stream / mix bus (not only booth headphones). Flip a utility to mono.
- A/B DI or pickup muted vs open under bridge/body mic, amp mic, and room. Note what disappears: fundamental, body, pizz attack, bow scrape.
- Solo pairs: DI vs mic, mic vs amp, stereo bed vs mono fold.
- Check correlation on the delivery bus, then with the bass muted vs full.
Order of operations (before spectral phase rotation)
1. Polarity between DI / pickup and bridge / body / amp
Flip DI vs mic, or mic vs amp, when fundamental or body return immediately on a clear pizz or bow attack. Guide: polarity vs phase. Cousins: electric bass DI + amp, dual-mic phase, why bass disappears in mono.
2. Small delay align secondary paths to the hero mic or DI image
Acoustic mics arrive later than DI. Amp mics and digital hops add more offset. A few samples of delay on the secondary often restores fundamental better than EQ for "more 80 Hz."
3. One hero upright bass image to the stream or mix bus
Do not send DI, bridge mic, body mic, amp, and room all hot into the livestream or print. Pick a hero Mid-safe path (often a focused mic+DI blend or a strong bridge mic), keep extras muted or low. Parallel stacks are classic hollow-bass on phone fold.
4. Prefer hero body / fundamental as the tone; quieter color grit or room
Amp grit and room air should color the hero image, not replace it for the stream mix. If every path sits at full level under a loud OH, mono fold almost always hollows the fundamental.
5. Skip wideners and Haas on upright bass beds before fold
Short-delay width and stereo imagers make booth headphones huge and phones hollow. Keep critical low end and body centered for stream and print. Primer: why bass disappears in mono.
6. Only then audition residual L/R spectral fights
If a stereo 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, rotator bypassed vs engaged. PHIXER belongs on residual stereo fights, not as a substitute for DI vs mic polarity.
Path types and typical failure modes
| Path | Common mono failure | First fix |
|---|---|---|
| DI / pickup + bridge / body mic | Fundamental / body cancel on stream | Polarity; delay secondary; quieter secondary |
| Mic + amp / cab mic | Grit stays, body hollows | Polarity + timing; hero Mid-safe path |
| Instrument + room / OH | Attack disappears on phone | Polarity + delay; hero image |
| Stereo pair hard L/R | Huge in cans, gone on phone | Center critical lows; simplify width |
| FOH / matrix → OBS / print | Fine in booth, hollow for viewers | OBS livestream / live FOH |
Studio / livestream checklist (to send)
1. Label DI vs mic vs amp vs room paths
Name DI/pickup, bridge, body, amp, and room/OH so operators know what hits the livestream or print. Ambiguous stacks get left open and comb on fold.
2. Mono-check delivery bus alone, then with full bass
Solo fundamental and body in mono. Then open pizz attack and bow scrape in mono. Note fights between grit color and hero body.
3. Watch phone, social, and archival destinations
Most remote viewers hear mono or near-mono. Guides: live FOH, OBS livestream, bass in mono.
4. Re-check after pickup blend or amp insert changes
Piezo blend, magnetic pickup, reamp boxes, and amp IR hops change delay and polarity. Flip and time-align again after any path change.
When PHIXER helps
- The material is already stereo and must stay stereo (stereo pair, stereo room or board print), not a mono DI you fake-widened.
- Polarity, delay align, and hero-path levels are cleaned up, but fold still hollows a band of the spectrum.
- You can A/B mono with the plugin bypassed and hear clearer body or fundamental without wrecking the image.
- You are not using it to "fix" unaligned DI+mic under room, or to replace a time-align edit on the matrix.
Decision table
| You notice… | First try | Why |
|---|---|---|
| Fundamental thins when DI opens under mic | Polarity; delay secondary; quieter secondary | Arrival-time / polarity fight |
| Mic + amp grit hollows body | Polarity; timing; hero Mid-safe path | Dual-path stack |
| Fine in booth, thin on phone | Mono delivery bus; pull extras | Booth ≠ viewer fold |
| Stereo bed still cancels by band | PHIXER on that stereo bed | Residual spectral L/R fight |
| Mono bass alone is dull | Tone / EQ / gain / mic choice | Not an L/R repair job |
When NOT to use PHIXER here
- You have not mono-auditioned the stream / mix bus yet.
- The fix is obviously polarity, delay, one hero image, or quieter secondary under mic/DI.
- You want PHIXER to make the bass louder, wider, or "more low end." Wrong job.
- The path is mono and the print problem is balance or EQ.
- You are mixing electric DI + cab and should use the electric bass DI + amp guide instead.
- See also when not to use PHIXER.
Quick path: Solo delivery bus in mono → polarity DI vs mic/amp → delay-align secondary → one hero image → quieter extras under hero → skip Haas/imagers → mono-check with full bass → PHIXER only for leftover stereo cancellation on a stereo bed → fold again for stream / studio print.
Related guides
- Bass DI + amp/cab dual-path phase (electric bass cousin)
- Why bass disappears in mono
- Dual-mic phase
- Bluegrass / acoustic string-band multi-mic phase
- String section / violin multi-mic phase
- Overhead & room mic phase
- Polarity vs phase rotation
- When not to use PHIXER
- Twitch / OBS livestream mono fold
- Live FOH / foldback / stream phase
Watch
- PHIXER tutorial + how it sounds (walkthrough with audio examples)