Gear Geek: Eventide H910 Harmonizer

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Eventide H910 users quickly discovered new ways of making its internal effects interact to produce previously unheard soundscapes.

In 1974, two years after Lexicon introduced the Varispeech—a pitch shifter designed for processing speech, not music—Eventide announced its first Harmonizer, the Model H910. It began shipping the next year with a street price of about $1,300, and studios everywhere added it to their racks almost immediately. According to Eventide engineer Tony Agnello, who invented the Harmonizer and is now the company''s CTO, the H910''s name pays homage to The Beatles'' song “One After 909.”

The H910 was a rackmount device that accepted an audio signal and generated a pitch-shifted version of that signal in real time. The output could be any interval within an octave higher or lower than the original. By singing into a microphone connected to the device, you could harmonize with yourself. With multiple Harmonizers, you could create an entire chorus of voices. The H910 also had a pair of built-in digital delays, each offering a maximum 112.5ms of delay time, as well as a Feedback knob for regenerating the delayed signal.

The Pitch Ratio Readout showed the ratio between the original pitch and the transposed pitch rather than actual pitch names. To dial in the pitch you wanted, you either referred to a chart or memorized the ratios for musical relationships. An optional, proprietary keyboard allowed you to control pitch by playing it in real time, and a polyphonic keyboard could control multiple Harmonizers to create chords from a single monophonic sound source.

The ability to turn a note into a chord is a real timesaver, but combined with other digital processing, Harmonizers exploit audio effects that would otherwise be impossible. In addition to producing semitone intervals, you could apply small amounts of shift to correct a previously recorded, out-of-tune instrument. You could use a pair of H910s to thicken sounds by simultaneously detuning them sharp and flat. By applying feedback to a pitch-shifted signal, each repetition could be pitched at an interval of the previous repetition, producing scales with the delay setting determining the length of time between tones.

Users included producer Tony Visconti, who relied heavily on the H910 for David Bowie''s albums Young Americans, Low, and Lodger. The unit contributed to hits by Steve Winwood, Hall & Oates, and other ''80s chart-toppers. Frank Zappa, Eddie Van Halen, and Jimmy Page famously made the H910 part of their signature guitar sounds.

Eventide''s subsequent Harmonizers offer longer delay times, more simultaneous harmonies, better fidelity, and other improvements. Today you''ll find plenty of plug-ins that do everything you could with an H910 and then some, but with greater fidelity and flexibility. Eventide''s H910 plug-in, part of the Anthology II TDM plug-in bundle, now comes closest to capturing its character.

Former EM senior editor Geary Yelton lives in Asheville, N.C., surrounded by beautiful mountains and wonderful toys.