Be Your Own Backup Singer With This Five-Voice Plug-In
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Be Your Own Backup Singer With This Five-Voice Plug-In


Click here tolisten to the exclusive Harmony Engine audio clips

Antares, creator of one of the oldest and most recognizable tricks in the DSP plug-in book, Auto-Tune, and the more recent and enigmatic AVOX vocal processing bundle, is playing the pitch-manipulation game again with Harmony Engine. Having positively reviewed the utilitarian-to-outrageous AVOX in the January 2006 issue of Remix, I was keen to try the California-based company's latest offering. Harmony Engine is a five-voice vocal harmony-generating plug-in for Mac OS X and Windows XP or Vista that works under a variety of DAW hosts. The generated vocal quintet includes the source as well as four individual harmony voices, each with a variety of independent controls such as gain and pan, vibrato, “throat length” and plenty more.


I downloaded the software from Antares' Website, where the company offers 10-day, fully functional demo versions of most of its current software line. The download screen lists individual links for each of the available plug-in formats. That makes for smaller downloads and minimized client hard-drive requirements at the potential expense of multiple installers for users of different hosts. I like this approach, and Antares assists with a description of each of the major plug-in format types.

I tested Harmony Engine on a Power Mac G5 dual 2.0 GHz with 1 GB of RAM, running Apple Logic Pro 7. I downloaded the 15 MB Audio Units Universal Binary version, which comes with support files and a well-illustrated 48-page PDF manual. The installation was a simple and quick affair; the installer tells you exactly which files will be placed where on your computer — a rare and nice touch, at least on a Mac. On first try, however, Logic didn't recognize Harmony Engine despite the documentation's assertion that Logic 7 is “fully supported.” Antares tech support was very helpful and thorough in its directions. Upon updating to Logic version 7.1.1, the plug-in was recognized — problem solved. Harmony Engine uses the increasingly common iLok system for authorization, which was as straightforward as the install. The scheme uses a single dongle that authorizes multiple software programs.

Harmony Engine 1.0 can route or export its five channels to individual DAW tracks for further processing. Antares suspects that factor has caused some incompatibility problems with some DAWs that don't support that function, but Antares is working to make sure hosts will simply disable that one function, rather than refuse Harmony Engine as an available plug-in. At the time of this writing, Logic was the only fully supported Audio Units host; Digital Performer 5 was listed as “partially supported” (no automation); and Steinberg Cubase SX 3.1/4, Nuendo 3.1/4, Wavelab 6 and Cakewalk Sonar 6.2 are all fully supported. On the other hand, Ableton Live 5/6, Bias Peak Pro, Adobe Audition and all Sony apps, including Acid, Sound Forge and Vegas were not yet listed as supported. Another noticeable omission is a TDM version, though RTAS is available for Pro Tools 7.x systems.

Once you clear the hurdle of owning a compatible host, Harmony Engine's interface looks clean, well-labeled and modern; all controls conveniently exist in a single window, and each of the five harmony voices is well laid out in channel-strip fashion. All voices (“channels”) have the following features in common: a linear Gain fader, a horizontal Pan fader, continuous level meters and Solo and Mute buttons (which come in very handy as you custom-sculpt your sound). The four harmony-generating channels have the remainder of their controls in common, including Interval (plus/minus 5th, 3rd, semitones, etc.), a physically modeled Throat Length presented on a vertical pot and four Vibrato controls, including Rate, Onset Delay, Pitch Amount and Amp Amount. Replacing the Vibrato section, the source channel contains drop-down menus for Input Vocal Range (Soprano, Alto/Tenor, Baritone/Bass, Instrument) and Model Glottal (Soft, Medium, Loud, Intense). The source channel also has a linear pot for Tracking; combined with the Vocal range controls, that enables you to best match and clone the source.

Global controls include various Humanize, Glide, Formant and Pitch Freeze components and a wide variety of harmony controls, including Key/Root, Scale, Harmony Source and more. Finally, MIDI controls and fully customizable Harmony and Voice Parameter Preset matrices are onboard for saving custom settings. One begins to see pretty quickly that Harmony Engine goes well beyond most automatic harmonic generators; while it's feasible to do something as simple as call up an instance of the plug-in and just let it fly, each of the harmonic voices can be micro-controlled: Choose a harmonic interval or fixed interval above or below the source, fine-tune the pitch, subtly enhance or subtract vibrato and alter the vibrato rate, etc. However, I also quickly discovered that using Harmony Engine out of the box was not adequate. To get a good sound, Harmony Engine absolutely requires tweaking.

Read more of the Remixreview of the Antares Harmony Engine 1.0


Auto-Tune and Harmony Engine are meant to complement each other; Harmony Engine is in no way a pitch-correction tool, so the source vocals need to be in tune first. The first project I threw at Harmony Engine was a male/female vocal duet accompanied by MIDI synth instrumentation. My first impressions were mixed. Placing the plug-in on either his or her vocal tracks worked okay out of the box, and when I tweaked the default settings with various basic combinations — a 5th up, a 5th down, an octave above, etc. — it sounded really good, with all five voices active, in context of the entire song. But as I soloed the effected vocal track, and even more so as I began to strip the harmonies down by soloing just a few of the voices, the clones sounded artificial, distinctly out of key and overprocessed, especially the further up or down from the original they were. The singers in these examples were a far cry from Mariah Carey, however, so I tried some other sources.

Next, I downloaded the “Let You Know” tutorial files from Antares' Website and went to work. The vocals in “Let You Know” are much more in-tune than my original samples, so I expected better results, and got them. However, the initial harmonies still sounded unnatural to me. I dug deeper to see if I could manually produce something harmonically correct and also natural sounding. Deep tweaking is the key with Harmony Engine. With careful mixing of the voices within the plug-in (especially soloing each voice by itself or against only the original while tweaking) and adjusting the throat length of each voice, I achieved good results for the full harmonies. Overall, the plug-in wasn't especially convincing or pleasing with fewer than three voices active unless small intervals were applied or if the instrumentation played on top essentially camouflaged some of Harmony Engine's processed artifacts.


Harmony Engine is capable of much more than just key- or semitone-based harmony generation; you can take any input signal (monotone or not) and generate single-note or complex chords with Harmony Source set to Chord Degrees or Chord Name. Simple drop-down lists allow you to select your desired key (regardless of the original input key), set the desired chord (various Major, Minor, Diminished, etc.), set the desired scale (Major/Flat 7th, Harmonic Minor, etc.), widen or shorten the chord's octave spread and slide the register from bass to treble. You can even use MIDI input, either over a single MIDI channel or one MIDI channel per voice, to generate chords — a very cool feature. Each note of a chord is played through one of the four channels, although with the exception of Multiple-Channel mode, they are automatically mapped from highest note to lowest from left to right — the opposite of a piano — which seems counterintuitive. All of this chord-generation capability is awesome, and unlike some of my earlier experiments, the chords sounded perfectly in-tune. However, the resulting sound quality of the solo voices still retains the artificial quality as described earlier.

There are finer details to Harmony Engine, but there isn't space to cover them here. Ultimately, the plug-in left me excited, with a wish list for the next version. Because many engineers may not possess perfect pitch or strong music theory or even know the key an original track is in, an automatic key and note finder for the input source — similar to a chord finder — would be a welcome addition, as would be a note readout on each channel for the Chord modes. A phase-reverse switch on each channel would also be useful, especially for same-note harmonies. Finally, allowing the Harmony Source to be channel-selectable instead of just global would be perhaps an advanced feature, but still welcome.

Harmony Engine's first version may not be a home run, but it's at least an RBI double. Its wide range of harmony-generating features is wrapped in an intuitive interface. It sounds great for four- or five-voice harmonies but less than convincing for note-separated duets and some trios. It also relies heavily on very in-tune sources. The plug-in gives sheet-music-challenged types a fairly easy means of generating complex harmonies, although without any source chord or note indicators, a solid music base is almost a prerequisite. Hopefully it will soon fully support a wider DAW base.

For exclusive Harmony Engine audio clips, go



Pros: Sophisticated harmony and chord generation. Individual voice mixing. Strong MIDI implementation. Intuitive interface. Low CPU usage.

Cons: Unconvincing voice quality in the upper and lower registers. Several notable DAW hosts not yet supported. Lacks note or chord-finder capabilities. iLok key sold separately.


Mac: G4/1.5 GHz; OS 10.4 or later; Pro Tools|HD or LE 7.x for RTAS or any VST or Audio Units host; iLok USB key (sold separately); valid account

PC: 1.7 GHz; Windows XP/Vista; Pro Tools|HD or LE 7.x for RTAS or any VST host; iLok USB key (sold separately); valid account