Official Guide v1.1.0 VST3 / Audio Unit Universal Binary (ARM64 / Intel)

AuxHarmonizer User Guide & Vocal Choir Manual

Real-time 4-voice polyphonic vocal harmonization, smart voice leading, Sibilance Lock protection, and DAW MIDI chord track integration.

1. Overview & Voicing Architecture

Generating vocal harmonies traditionally requires either stacking dozens of vocal takes or using mechanical pitch shifters that sound like metallic vocoders. AuxHarmonizer creates lush 4-part polyphonic harmonies from a single solo vocal take, either automatically using smart diatonic scale detection or driven live by your MIDI keyboard. Crucially, its proprietary Sibilance Lock detects and isolates consonants ("s", "t", "ch") so backing voices never produce harsh, clustered sibilant clutter.

Humanize & Acoustic Micro-Timing

Real ensemble singers never sing at the exact same microsecond or pitch. AuxHarmonizer's Humanize engine injects subtle stochastic timing drifts and micro-pitch imperfections, completely eliminating synthetic comb filtering and phase cancellation.

2. Complete Knob & Parameter Reference

Knob Name	Parameter ID	Range & Unit	Default	Acoustic Function & Listening Tip
Harmony Level	`harmony_gain`	0.0% – 100.0%	100.0%	Master Harmony Trim. Controls the overall master output level of all active synthesized backing voices simultaneously.
Lead Level	`lead_gain`	0.0% – 100.0%	100.0%	Lead Vocal Trim. Controls the volume of the unprocessed original singer. When running AuxHarmonizer on an Aux Return track, pull to 0% (or use `Mute Lead`).
Humanize	`humanize`	0.0% – 100.0%	25.0%	Micro-Timing & Pitch Drift. Injects natural human imperfections into each voice. At 0%, sounds like a clean electronic vocoder; at 35%–50%, sounds like an organic choir of separate people.
Sibilance Lock	`sibilance_lock`	0.0% – 100.0%	50.0%	Consonant Decoupling. Detects transient unvoiced consonants ("s", "t", "p") and prevents them from generating multi-layered pitch copies. Eliminates harsh sibilant build-up.
Throat	`throat`	-100% – +100%	0%	Choir Vocal Tract. Global formant offset applied across all harmony voices. Negative values create youth/female choir ensembles; positive values create deep baritone choirs.
Tube Drive	`tube_drive`	0.0% – 100.0%	0.0%	Harmonic Glue. Warm vacuum-tube saturation on the combined harmony bus. Melts the synthetic voices together into a unified acoustic choir.
Stereo Spread	`stereo_spread`	0.0% – 100.0%	50.0%	Stereo Field Width. Scales the individual pan positions of Voices 1–4 outward from center. At 100%, envelopes the listener in massive wide harmonies.
Snap Speed	`snap_speed`	0.0% – 100.0%	50.0%	Tracking Speed. Controls how quickly harmony pitches snap to incoming vocal notes in Chord/Auto mode. Slower values glide smoothly; faster values lock tightly.

The 4 Independent Voice Strips

Each of the four synthetic voices features full dedicated control over spatial panning, volume, pitch interval, and individual singer formant character:

Voice 1 (V1) Active

Default Pan: -45% (Mid-Left)

Default Interval: +4 st (Major 3rd)

Formant: 0 st

Voice 2 (V2) Active

Default Pan: +45% (Mid-Right)

Default Interval: +7 st (Perfect 5th)

Formant: 0 st

Voice 3 (V3) Active

Default Pan: -85% (Hard Left)

Default Interval: -5 st (Low 4th)

Formant: -2 st (Deep)

Voice 4 (V4) Active

Default Pan: +85% (Hard Right)

Default Interval: +12 st (Octave Up)

Formant: +2 st (Air)

3. Operating Modes & Intelligent Voicing

Chord / Auto Mode Diatonic Intelligent

Analyzes your incoming vocal melody and automatically derives musically correct harmonies based on your selected Root Key and Scale. Features built-in Smart Voicing and Voice Leading logic to prevent dissonant clashes and awkward voice crossing.

MIDI Track Mode External Polyphonic

Receives live MIDI note chords from a designated DAW MIDI track. Sing any single note into your microphone while playing chords on your keyboard: AuxHarmonizer instantly generates a multi-part polyphonic choir conforming to your exact keyboard voicings.

Low Latency Live Tracking Toggle

When tracking a vocalist live in studio headphones, engage Low Latency. This bypasses multi-frame lookahead buffers to achieve instantaneous monitoring without headphone delay. Disengage during final mix export for maximum DSP precision.

4. Battle-Tested Mix Recommendations

Recipe 1: The Auxiliary Send 4-Part Pop Choir

Aux Return Bus

Create an auxiliary return track with AuxHarmonizer inserted. Mute the dry lead vocal and blend the lush stereo choir in behind the singer during chorus sections.

Mode: Chord / Auto (Song Key)

Lead Mute: ON (100% Wet)

Sibilance Lock: 80%

Humanize: 35%

Stereo Spread: 85%

Tube Drive: 20%

Acoustic Result: A rich, wide vocal bed wraps around the lead singer without doubling dry lead gain or creating harsh sibilant buildup.

Recipe 2: Real-Time MIDI Gospel / Jazz Vocoder

Lead Vocal + MIDI Route

Route a MIDI keyboard track to AuxHarmonizer in Ableton, Logic, or FL Studio to control complex polyphonic voicings in real time.

Mode: MIDI Track

Lead Level: 65%

Harmony Level: 100%

Sibilance Lock: 65%

Tube Drive: 30%

Humanize: 20%

Acoustic Result: Sing any note into your microphone while pressing jazz or gospel chords on your keyboard to instantly hear lush, emotional choral chords.

Recipe 3: 3-Octave Monster / Air Stack

Direct Insert Post-Compressor

Thicken a modern rock or hip-hop vocal hook with sub-octave chest punch and high octave air while keeping everything centered.

Voices Active: V1 and V4 only (Mute V2 & V3)

Voice 1: -12 st, Formant -3 st, Pan 0%

Voice 4: +12 st, Formant +2 st, Pan 0%

Harmony Level: 35%

Sibilance Lock: 90%

Acoustic Result: Creates an imposing, modern 3-octave lead stack anchored firmly in the center of the mix.