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Korg Prophecy

Solo Synthesizer (Preview) By SOS Team
Published May 1995

Two months ago, Korg unveiled their OASYS high‑end physical modelling synth, and already a low‑cost spin‑off is just around the corner. SOS staff were amongst the first to hear it.

Korg's OASYS, previewed in March 1995's SOS, is a high‑end, polyphonic synth, capable of emulating any kind of synthesis, including physical modelling. Now Korg has unveiled another brand new instrument, the Prophecy, at the 1995 Frankfurt Musik Messe.

The Prophecy is a monophonic solo instrument with a projected price that puts it into the 'I gotta get one' bracket (at the time of writing, this would appear to be in the region of £1200). Unlike Yamaha's VL1, which takes a highly sophisticated approach to emulating wind instruments, the Prophecy encompasses a greater breadth of sound types, but I suspect that the sophistication level has been constrained to make the instrument both affordable and more manageable.

The Prophecy actually looks quite small with its 37‑note keyboard, but it can sound as huge as you like. One of the benefits carried over from the OASYS is the capability to handle several different types of synthesis — analogue, VPM (Korg's approach to FM synthesis) and physical modelling. The modelling section covers brass, reed, and plucked instruments, and the real‑time articulation comes from two control wheels and a ribbon controller, plus MIDI modulation sources, including velocity and aftertouch. No breath controller is built in, although those who want one can patch in something like an Anatek breath control box. The Prophecy also includes an effects section which can provide distortion, wah, parametric EQ, chorus/flange and delay/reverb. Because all the controllers use conventional MIDI data, the output of the Prophecy can be recorded into and replayed from a MIDI sequencer in the usual way.

You might ask how a DSP‑based synth handles analogue synthesis, but from what we've heard, there are no worries in this area. The two main oscillators are augmented by a sub‑oscillator, a noise generator and extensive modulation facilities, including LFO, oscillator sync and other analogue stalwarts. The filter (which may be set to high‑pass, low‑pass, band‑pass or band‑reject modes) sounded very analogue, and we were treated to a variety of 'bass sounds to kill for' — searing Moog‑style leads and filter sweeps. If I hadn't been told this was a digital machine, I would have accepted the analogue sounds without question. The FM — sorry, VPM — sounds produced all the classic 'metal things being hit' that the DX7 was so famous for, as well as some big, angry, modulated sounds reminiscent of someone dismantling a corrugated iron shed with a chainsaw, monitored through a flanger. No worries there either.

Finally came the modelling, and considering that the player wasn't dribbling into a breath controller at the time, the wind sounds were very convincing. The plucked sounds also worked well, especially the fretless and slapped bass.

Looking at the block diagram (Figure 1), the physical modelling side of the Prophecy seems unusual; instead of modelling the entire instrument, it would appear that an oscillator generates the basic waveforms, and these are fed through a waveshaping section, where the tonal articulation associated with modelling is applied. From there, the signal passes through the conventional filters, VCAs and effects, for further tonal shaping. I would imagine that this simplifying of the modelling process is what makes it possible to produce the Prophecy at such a low cost. The simplified modelling also makes the Prophecy relatively simple to program. There are 128 programs, and an arpeggiator with five preset and five user patterns. Further patterns and program data may be stored on a data card. Considering this was a pre‑production instrument, it seemed very close to completion, but we'll have to wait until summer before we can have one. I don't think I need to be a prophet to predict that the Prophecy is going to be in demand. It could change the face of your Barclaycard statement forever!