Quadravox

Eventide Quadravox is not a new plugin, and that is part of why it is worth writing about. It first arrived in 2016, and Eventide even gave it away free for a spell in 2019, so plenty of producers already have it sitting unused in a folder somewhere. It is still on sale, still supported, and still one of the more interesting harmonisers you can run, especially if you make electronic music rather than the vocals and guitars most reviews focus on.

I came to it after using Eventide's H910 plugin for a while and wanting something with more voices and more programmable timing. Quadravox is a four-voice diatonic pitch shifter built on technology from Eventide's flagship H8000FW processor, and it carries the same pitch-shifting heritage as the classic Eventide Harmonizer hardware that has been a studio fixture since the 1970s. This review looks at it from a house and dance production angle, with a bit of honesty about where it falls short.

Jump to:

• What is Eventide Quadravox?
• How does Quadravox sound on synths and for dance music?
• What features are worth knowing?
• Does Quadravox handle MIDI and automation?
• What are the downsides?
• Are there free alternatives to Quadravox?
• Is Eventide Quadravox worth it?
• FAQ
• Review Summary
• Where To Buy Quadravox

What is Eventide Quadravox?

Quadravox is a four-voice diatonic pitch shifter. In plain terms, you feed it audio, tell it a key and scale, and it generates up to four extra voices that stay in that key. Because the shifting is diatonic, each voice snaps to a note that belongs to the scale you chose, rather than a fixed number of semitones, so the harmonies stay musical as the source moves.

Each of the four voices has its own level, pan, delay with feedback, and pitch. You set all of that either with the sliders and typed values, or by dragging voices around the Notation Grid, which lays the pitches out on a musical stave with timing running left to right. Colour and brightness show pan and level at a glance. It is a genuinely quick way to work if you can read a stave, and it is the feature that separates Quadravox from a plain pitch-shift box.

This is a different job to something like Scaler 3. Scaler generates MIDI chords and progressions for you to play into an instrument. Quadravox does not touch MIDI notes at all. It harmonises the audio you already have, following the key and scale you set. The two can sit happily in the same project, but they are not doing the same thing.

How does Quadravox sound on synths and for dance music?

On synths it sounds clean and tight, and it turns single-note parts into stacked harmonies, panned sequences and tempo-locked grooves. Most Quadravox coverage centres on backing vocals and guitar, so this is the side that is less written about, and for dance music it is arguably the more useful one.

To test it I dropped a simple eight-bar poly synth loop into Bitwig at 140 BPM, a single-note part with nothing clever going on, and worked through the voices. With one voice active you get a straightforward harmony you can pan and time. Add a second and you can bring it in on the beat or offset it so it answers the first. Build up all four and you can stack cinematic harmonies or spread notes across the stereo field for width.

The preset banks are where the dance potential shows. The sequence presets are the standout. One of them sets voices one and three panned left, voices two and four panned right, with delays between them and a mix of fourths, fifths and an octave up. Play a plain riff through it and you get a moving, panned sequence that works well as the basis for a bassline or a lead hook. Because the per-voice delays sync to your session tempo, short times and small shifts thicken and widen a sound, while longer times and larger shifts build arpeggiated grooves.

One important setting: pitch tracking. With it on, Quadravox follows a single detected pitch, so it is happiest on monophonic sources. Turn pitch tracking off and it stops trying to read a note and treats the input as raw material, which is how you get it working on chords, drums and rhythmic parts. That switch is the difference between it fighting your source and it transforming it.

What features are worth knowing?

Beyond the four voices and the Notation Grid, a few things are easy to miss and worth your time:

Live Mode trims the default 40ms latency that Quadravox normally runs in. So with this mode on you can audition and perform in real time. The trade-off is quality, so the sensible workflow is to switch Live Mode on while you experiment, then switch it off when you commit to a sound for the cleanest result.

Does Quadravox handle MIDI and automation?

Set your expectations correctly here. Quadravox is an audio effect, not an instrument. You do not play MIDI notes into it to trigger harmonies. It follows the key and scale you set and tracks the pitch of the audio you send it. For anything you want to move over time, use your DAW's parameter automation. In Bitwig, for example, you can right-click a control such as delay, feedback, shift or loop and automate it from there. There is no interface-level MIDI learn, so your host is where that work happens.

What are the downsides?

For me I found that pitch tracking takes care on expressive vocal lines. It can occasionally misread a note and send a voice off in the wrong direction, and dialling that in properly is fiddly. Again, this is more of an issue on vocals than on steady synth or instrument parts.

Also, Quadravox is managed through iLok, which adds a setup step, and it is a specialised tool rather than an everyday utility. You will reach for it deliberately, not on every track. I'm not a fan of iLok as you'll know from my Substack rants, but I also understand why it's there.

Are there free alternatives to Quadravox?

If you want to test the water before buying, a few free harmonisers get you part of the way. None of them match the four-voice Notation Grid and tempo-synced delays, but they cover the basics.

• Pitchproof by Aegean Music is a free diatonic pitch shifter and harmoniser. It works well on monophonic sources such as vocals, guitar solos and single-note synth lines, and it has a guitar tuner built in. It does produce audible artefacts on polyphonic material, so keep it to one note at a time.
• Duet by Martin Eastwood Audio is a free Windows VST double-tracker and harmoniser, good for width, thickening and doubling on vocals and synths.
• Graillon 2 by Auburn Sounds is a freemium pitch correction and harmony tool. The free version gives you autotune-style correction plus a pitch-shift voice you can use for a simple harmony, with the full feature set behind a paid upgrade.

For more options in that vein, see the Audioblob free VST plugin list. If you would rather spend a little and get a lot, the 10 plugins under £30 roundup is a better starting point than most freebies.

If you go the other way and want more voices, Eventide's Octavox is the eight-voice version of the same engine, with more presets. Quadravox is the smaller, more affordable four-voice option.

Is Eventide Quadravox worth it?

For creative harmony and sequence work, yes. It is quick, musical and distinctly Eventide, and it earns its place on synths, riffs, guitar and rhythmic material with pitch tracking off. The Notation Grid and the tempo-synced delays make it a compositional tool as much as an effect, and it turns plain parts into something with movement. It also turns up cheaply in Eventide and Plugin Boutique sales fairly regularly.

Where it is less convincing is polished vocal harmony, purely because of the missing formant control. If clean, natural backing vocals are your main goal, budget for extra tidying or a different tool. If you want a harmoniser that inspires ideas and reshapes sounds, Quadravox still holds up well.

If you already like Eventide's approach to effects, it sits comfortably alongside something like Eventide Blackhole, and it pairs neatly with a dedicated vocal processor such as the one covered in the VoxGuru review when you do want to work on voices.

FAQ