#Eventide h910 full#
Popularized by Jimmy Page (as the only piece of digital gear to grace his rig) and cherished by Suzanne Ciani, the H949’s full feature set is recreated in this plug-in. When used as a variable-speed tape recorder, the Harmonizer® is capable of shortening or lengthening a piece of program material to fit a given time slot without altering the pitch.” The TIME REVERSAL feature is entirely new. “…a combination digital delay line, pitch changer, and all-around special effects unit. Here’s how it was described when first introduced: The H949 also offered unique flange, reverse, and randomized pitch effects. Produced from 1979–1984, it introduced MicroPitch which used a proprietary single sideband modulation technique for precise control of small pitch shifts. Since the audio on each side of the discontinuity cannot be controlled or determined, these glitches can be quite nasty, full scale clicks or complete drop outs.Building on the legacy of the H910 Harmonizer, the H949 was Eventide’s first de-glitched pitch shifter. As the pitch ratio moves away from unison, the glitches occur more and more frequently. For pitch ratios close to unison (pitch ratio ~1.00), the delay changes slowly and glitches occur infrequently.
What does the glitch sound like? How noticeable is it? Well, that depends on the pitch ratio and the audio source. Of course, the instantaneous jump results in a “discontinuity” in the audio signal. Use a ‘circular delay buffer’ of some length (typically 20-30 msec) with the delay abruptly jumping from zero to max in the case of increasing pitch (decreasing delay) and from max to zero in the case of decreasing pitch (increasing delay). The ‘solution’ is both simple and imperfect. In fact, for real-time performance, it’s best to limit maximum delay to no greater than ~20 msec. Delay can’t decrease past zero (that would require a magical digital “advance” line). It helps to think of this as increasing pitch by decreasing delay and decreasing pitch by increasing delay. If you continuously read from memory slower than you write to it, the delay will grow until you’ve completely filled up the memory. If you increase pitch by continuously reading from memory faster than you write to it, you’ll run out of data. The challenge for a real-time pitch changer that does not change tempo is rather obvious. Of course, as with tape, the audio plays back at a faster or slower rate. This is the equivalent of recording to tape at one speed and playing back at another speed. Random Access Memory ICs became commercially available and pitch change was made possible by reading the audio from memory (playing back) at a different rate than writing (recording). The Challenge: Pitch Change Without Speed Changeīy 1975, IC technology had sufficiently advanced to the point that it became practical to design a digital pitch change effects box - the H910. However, the interface was not designed to easily dial in pitch-related effects, and there was a technical challenge to overcome. Eventide’s DDL1745M had an optional pitch change module and a handful of studios began to discover digital effects. Offering pitch shifting (1 octave), delay (up to 112.5 ms), feedback regeneration and more from an easy-to-use. With memory for audio was just becoming possible, the H910 was the right box at the right time, says Agnello. Prior to its introduction, studios had adopted digital delay as a utilitarian tool to replace the bother of using an expensive tape machine (and salaried tape op) for double tracking and plate reverb pre-delay. Unveiled in 1975, Eventide’s H910 Harmonizer pitch shifter spawned a legacy of products that continues to this day.
#Eventide h910 pro#
The H910 was arguably the first pro audio digital effects product. Just three years later, Buys Ballot, a Dutchman, demonstrated the Doppler Effect on sound waves by having six tubas play the same sustained note while perched on the front of a speeding locomotive.
In 1842, Christian Doppler suggested that “the observed frequency of a wave depends on the relative speed of the source and the observer.” Doppler was thinking about star light, not sound, but a wave is a wave is a wave. (Kids whirling objects around on a string were not the scientific observers for which one would have hoped.) To notice even a slight pitch change of 2% a sound source with 100% constant pitch would have to be approaching the listener at 15 mph. Why had no one elucidated this effect in our long history? It’s simple few things moved fast enough! Sound travels at ~750 mph. While Pitch Change is naturally occurring, throughout history, humans would rarely have perceived the effect because the sound source must be traveling at a high enough rate of speed relative to the listener to cause a discernible change in pitch. There’s a lot of history to cover about the conception and development of the Harmonizer so let’s first consider the underlying principle: the interesting phenomenon known as Pitch Change.
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