Arturia iProphet is a classic vector synth in your backpack

May 22, 2015

Despite its relative obscurity, the Sequential Prophet-VS was one of the most innovative synths of the mid-’80s. Released just a year before the company was sold to Yamaha (and products discontinued), the Prophet-VS unleashed an entirely new form of waveform manipulation for synthesists. Called “Vector Synthesis,” this method of tone generation was based on four digital oscillators, each with its own waveform and tuning, that could be blended in real time or via a set of automation tools that blurred the line between envelopes and LFOs. The results were similar to the PPG Wave’s ability to scan through a wavetable and shifting timbres, but far more flexible, since the VS was able to smoothly transition between a much wider variety of harmonic spectra.

Arturia's newest iOS app iProphet is an impressive recreation of the VS sound, incorporating nearly all of the original’s features into a much more intuitive interface, and adding a few essential effects that thicken the sound nicely.

The original Prophet-VS oscillator topology is reproduced faithfully here. Each of the four oscillators includes coarse and fine tuning for an array of 95 single cycle digital waves that cover a lot of sonic ground and have a distinctly vintage ’80s vibe. Once you’ve adjusted these options for each oscillator, you can then mix and blend them via a virtual joystick to create really deep textures or (with a little advance planning) chords.

Things get a lot more interesting when you apply Arturia's visual implementation of the VS’ envelope-based mixer for the oscillator blending. Here, you can specify five different joystick positions and then set the transition times between each point, allowing you to shift smoothly between waveforms and tunings. What’s more, this envelope can be set to loop between a variety of positions, allowing for LFO effects. The end results can range from shimmering animated pads to percussive patches that quickly whip through timbre shifts in clever ways. While there are other modern iOS synths that perform similar tricks, the VS interface distinguishes iProphet from the competition.

From there, the rest of the iProphet’s synthesis engine covers the classic analog/subtractive territory, but with a few improvements and modern Arturia enhancements. For example, iProphet retains the original’s innovative five-stage envelopes for the filter and amp—each with separate parameters for level and time--but with the enhancement of being graphically editable. As for the filter, it’s got the standard complement of cutoff, resonance, and envelope amount, but Arturia also gave it modern multi-mode options. The tempo-synced dual LFOs cover familiar territory, with controls for rate and the five essential waveforms: triangle, square, saw up or down, and random.

Another enhancement is a pin-based modulation matrix, evocative of the legendary EMS VCS3. Here you can route the LFOs, envelopes, keyboard tracking, modulation wheel, and iPad accelerometers to a variety of iProphet’s synthesis functions. Interestingly, the depth of modulation is governed in a semi-global way for each modulation source. For example, you can route the filter envelope to the frequency of oscillators A and D, but the amount will be the same for both. This isn’t a drawback, as this “limitation” gives iProphet some extra character.

While iProphet doesn’t include the original’s unusual arpeggiator, it does include its chorus, along with an overdrive stage and a stereo delay. As for iOS communication, there’s Audiobus, Core MIDI, Apple Inter-App audio, and even Tabletop if that’s your preferred standard.

All in all, iProphet is a knockout classic synth emulation for the iPad, and for a mere five bucks, an obvious Key Buy.

PROS

Faithful recreation of the Prophet-VS vector synthesis engine. Intuitive interface design makes managing oscillators and blending a breeze. Multimode filters. Integrated chorus, overdrive and delay.

CONS

The user-designable waveform tools of the Prophet-VS are not included, nor is its innovative arpeggiator.

Bottom Line

A classic in your backpack.

$4.99 | arturia.com


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