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Monday, November 11, 2013

Product Review - Dave Smith Instruments Prophet 12

Article Preview :: Polyphonic Synthesizer

Reviews : Keyboard

A new Prophet is always an exciting prospect, but the name certainly carries a weight of expectation. Can the latest model live up to its illustrious ancestry?
Gordon Reid

Thirty-five years after it was first attached to a synthesizer, the Prophet name still invokes awe, and the day isn't long enough to list all of the musicians who have achieved great things using Prophet 5s, 10s, 600s and T8s. Consequently, there's always an air of expectation when a new Prophet is announced. But is it justified? Does a world replete with workstations offering multiple virtual analogue engines, gigabyte samplers, sequencers, terabyte hard disk recorders and gazillions of effects need another 12-voice hybrid polysynth?

The Prophet 12 comprises two six-voice synthesizers called Layer A and Layer B. These can be played individually, layered, or placed either side of a split point, so you can use the Prophet 12 as a single 12-voice polysynth, as a six-voice bi-timbral synth, or as two independent six-voice synths. Happily, it doesn't require dozens of hidden functions and tiers of menus to achieve all of this. Much of what it can do is immediately accessible from its control panel, so it gives of its best quickly, even to relative novices. Nonetheless, there's more here than meets a casual glance, so let's start by working through the voice structure and seeing what we can place into each of those Layers.



There has been much gossip among the chattering classes about the hybrid analogue/digital nature of the Prophet 12. Nowhere is this more relevant than the oscillators, which are generated by no fewer than six SHARC chips, each of which handles the digital elements of two voices. This is a non-trivial amount of processing power, but with four oscillators per voice, each with coarse and fine tuning, slop (tuning instability) and independent portamento, plus a sine wave sub-oscillator one octave below Osc 1, that's a total of up to 60 waveforms being generated at any given moment, which is not trivial if you're going to do it correctly.

Dave Smith Instruments Prophet 12 

Each oscillator offers the standard set of analogue-style waveforms, each with waveshaping options. The best-known form of waveshaping is pulse-width modulation, but there are other shapers for the sawtooth, triangle and sine waves, and even for the three noise colours.

There are also 12 additional waves, chosen to expand the initial palette in interesting ways. These have names such as Nasal, Ohhhh, Ahhh and Buzzz, which give you a rough idea of what they sound like, and of the uses to which they can be put. Instead of waveshaping, the additional waves allow you to select a base waveform, place one of the other shapes to its left and another to its right, and crossfade (or, in modern parlance, morph) between them, either to obtain new static waveshapes, or to create unusual dynamic waveforms.

As you would expect, the waveshaping and morphing of all of these sources can be controlled by the LFOs, the contours, and many other facilities available through the modulation matrix (which we'll address in a moment) and you can set this up independently for each of the oscillators in a voice, so the initial sound can become very detailed, very quickly.

You'll also find controls within the oscillator section for Amplitude Modulation, Frequency Modulation ('cross-mod') and a button for hard sync. The ring to the left of these shows which oscillators are active at any given time, and the preset routings of the AM, FM and sync sources and destinations: Osc 4 affects Osc 3; Osc 3 affects Osc 2, and so on. This is a powerful architecture. For example, you can have two sync'ed pairs in a single voice, or a sync'ed pair and a two-operator FM sound, or a three-op FM sound and an unmolested oscillator, or... well, you get the picture. Except that you don't, because you can also assign and route the oscillators within the modulation matrix. This fully vindicates DSI's decision to use digital oscillators, because even the smallest deviations between voices would result in excessive tonal differences between notes and render polyphonic patches unusable.


'Character', VCFs & VCA

Given the degree to which the initial waveforms and tunings can be modulated, and the myriad ways in which the AM and FM amounts can be modified within the Prophet 12, the tonal possibilities are enormous even without invoking filters and other effects, and careful programming generates sounds that would never be available on a pure analogue polysynth (or, for that matter, many digital ones). Nonetheless, whereas the filter section would immediately follow the oscillators on most synths, the Prophet 12 has an additional waveshaping section positioned prior to the filter. This is called Character, and it offers five ways to mangle

Published in SOS November 2013

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