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Korg Prophecy

Solo Synthesizer By Gordon Reid
Published October 1995

It's not a new synth — it's seven! Korg's amazing new Prophecy offers analogue and FM synthesis, and physical modelling, and still costs under £1000. Unsurprisingly, SOS staff have been dying to review one ever since it was unveiled at this year's Frankfurt Musik Messe. Lucky man Gordon Reid won the toss...

This is the story as it was told to me... In 1987, the former Sequential Circuits design team (responsible for classics such as the Prophet 5 and Prophet VS) began working for Korg. The company immediately bundled them out of sight, locked them in a room full of computers and said "design something for us". Locks were locked, bolts were bolted, and most people forgot that they had ever existed.

Years passed. Every day somebody from Korg would shove some food and water through a hole in the door. Then, one day, there was a timorous knock from inside. Locks were unlocked and bolts were drawn. When the door was opened, a pasty‑faced individual peeked out, blinked in the light, and said, "We've designed something. It's called a Wavestation". "What does it do?" asked the guys from Korg. "Well, it's sort of a wavetable synthesizer, with vector synthesis, and wave sequencing". "Not bad" said the guys from Korg. "Now get back inside and design something else".

Years passed. Every day somebody from Korg would shove some food and water through a hole in the door. Then, one day, there was another timorous knock from inside. The door was opened, and an even pastier‑faced individual peeked out, blinked in the light, and said "We've designed something else". "What does it do this time?" asked the guys from Korg. "Well, it does analogue synthesis" said the pasty‑faced one. "And FM. Oh yes... and physical modelling of plucked strings. And brass. And reeds. And it can be programmed to handle any new synthesis techniques that may come along in the future... and it does them all simultaneously. We've called it the Open Architecture Synthesis System, or OASYS for short."

The executives at Korg were delighted, and instead of shoving the team back into their room, bought them dinner at an expensive Japanese restaurant. But there was a problem. At £10,000, the OASYS was expensive. Very expensive. So Korg turned to the developers and said, "Sorry guys, we've got to put you back in your room. We need something cheaper, something that will appeal to the average musician. Something, to be blunt, that we can sell in the mass markets."

Months passed. Every day somebody from Korg would shove some food and water through the hole in the door. Then, quite recently, there was a knock from inside. An extremely pasty‑faced individual peeked out and said, "We've done what you asked". "What does it do?" asked the guys from Korg. "Well, it does analogue synthesis" said the pasty‑faced one. "And FM. Oh yes... and physical modelling of plucked strings. And brass. And reeds. And, before you shove us back in the room... it does all that for less than £1,000." Thus did the Prophecy, as they say, come to pass.

Outside And In

Externally, the Korg Prophecy is a light but robust 37‑note monosynth with a velocity‑ and aftertouch‑sensitive keyboard. The styling is, to my eyes, new and refreshing, although a few people have commented on its similarities to the Yamaha VL1... A 2 x 40‑character backlit LCD dominates the control panel, and is surrounded by buttons to the left and right, and knobs underneath. Conventional modulation and pitch‑bend wheels, plus the 'log' (a combined mod‑wheel and pressure‑sensitive ribbon controller), round off the package. Most people will either love it or hate it. I love it...

Round the back, you'll find the inevitable MIDI In, Out and Thru, alongside inputs for an expression pedal, an on/off (sustain) foot‑switch, and a socket for an EC5 MIDI controller. This can be used for patch selection when your hands are otherwise occupied. There's also a socket for a RAM card that will store arpeggiator patterns as well as patches. And, finally, there are the stereo audio outputs.

Internally, the Prophecy is just a computer, although it boasts no fewer than five processors. Three of these are the Texas Instruments TMS57002 DSPs used in the Korg G‑series effects. The other two are for housekeeping: an NEC V55 looks after the user interface, key‑scanning, and display, and a Toshiba H8 (which I've never heard of) looks after the three DSPs.


You programme the Prophecy using the five knobs known as Performance Editors (which can also modify sounds in real‑time for live synthesis) and 32 of the 40 multi‑function pushbuttons. But be warned... as soon as you start playing with the editing, you start losing chunks of your life: begin fiddling at 8.00pm, and suddenly the sun is coming up.

Why is it so involved? Answer: Sheer synthesis power. For example, although the Prophecy features five distinct methods of synthesis, it offers nine oscillator types. These are: analogue, VPM (Korg's term to get around the fact that they can't use FM to describe this kind of synthesis), brass modelling, reed modelling, plucked modelling, noise + comb‑filtering, and three analogue‑style sync, ring‑modulated, and cross‑modulated models grouped under the family name 'MOD'. Each of these is a synthesis system in itself, and, with the possible exception of VPM, Korg could probably justify a thousand smackers for any one of them.

So let's take a single model — the somewhat obscure 'noise and comb‑filter' — as an example. This takes noise and passes it through a comb filter that can be modulated, enveloped, fed back, and filtered again. The model has seven pages of 'common' parameters, a further seven pages for each of the two virtual oscillators, a page for the white noise generator, and a page for the sub‑oscillator. That's a total of 66 parameters for the oscillators alone! But hang on... many of those parameters are simply the 'amounts' by which the assignable LFOs and envelope generators are applied. There are four LFOs, each offering four programming pages that contain 11 parameters, and six assignable 5‑stage ADBSR envelope generators, each with four pages containing 18 parameters. Oh, and don't forget the two wave‑shapers, the 10 mixer options, the two multi‑mode resonant filters, or the feedback loop from the final output back into the mixer. If this hasn't given you a complete mental breakdown, bear in mind that just about everything can be routed just about everywhere. The bottom line is this: if you were to read a 4000‑word review of a synthesizer that offered only the Prophecy's comb‑filter model, it would still be superficial. Get the picture?

A League Of Its Own?

Now, how about considering the other six models? No, I can't face it either, especially since Korg, in a particularly sadistic moment, created 'sets' that combine the nine oscillator types in 12 different ways. Nine of these are dual‑model modes that combine nearly every possible configuration of the analogue, VPM, comb, and modulation models (only MOD + MOD is missing). The other three are the single‑oscillator brass, reed, and plucked models. But there's yet another reason to tear your hair out — the instrument models are families. For example, the reed model offers not one, but 13 physical models: soprano sax, alto sax 1, alto sax 2, tenor sax 1, tenor sax 2, baritone sax, flute, single reed, double reed, recorder, bottle, glass bottle, and 'monster' — each with a markedly different character. You can't escape the dawning realisation that this is a synthesizer in a league of its own.

Let's escape from all this mind‑bending complexity by considering something straightforward and easily understood... like an LFO. Ooops, wrong again! Each Prophecy LFO offers 30 (!) waveforms and can simultaneously modulate up to 65 parameters in differing amounts and with differing polarities. This flexibility is matched only by how well the LFOs have been thought out. For example, you can imitate a guitarist's vibrato by choosing the appropriate waveform, and then offsetting it so that the pitch only goes up, not down. Alternatively, you can choose one of the exponential waveforms for stunningly realistic 'flutters', such as those produced by flutes and piccolos. You can even define an LFO to have a rate of zero. If this has a non‑zero offset it acts as an AR envelope generator that can be 'played' directly from the keyboard or any other controller, thus increasing the Prophecy's complement of EGs from six to a maximum of 10!

Still with us? OK, but then there are the programmable effects to consider: two types of wave‑shaping, overdrive, wah‑wah, distortion, chorus, flanging, panning, delay, and reverb. You can twist each Prophecy voice out of recognition simply by playing with these. In addition, and like the great synthesizers of yore, the Prophecy also offers an arpeggiator. This can be set to operate over a range of one, two, three or four octaves, in one of five different preset or five user‑definable patterns. It also offers latching and key‑sync, has variable velocity, and is 'live' to controllers. The gate length (and therefore the nature of many sounds) can be manipulated to take advantage of the portamento and triggering. Finally, you can limit the range of the keyboard over which the arpeggio will be defined. The Prophecy will even sort your notes into desired inversions!

Moving on, there are the 11 alternative scales, high priority, low priority, and last‑note keying modes, single triggering, multi‑triggering and velocity‑sensitive triggering, adjustable sensitivity curves... etc etc.


Of course, none of the above would be worth a brass farthing (or should that be a 'modelled, virtual brass farthing'?) if the resulting sounds were naff. And you can't always trust first impressions, because factory sounds can often be a bit like the emperor's new clothes. Even the most uninspiring synth will have a few good sounds placed in locations 00, 01 and so on, where even the most disinterested punters can stumble across them. So how can you tell whether a synth is still going to inspire you two years after you bought it?

When you consider the functions the Prophecy offers for the price (less than £1,000, remember) there's almost no excuse for buying anything else.

For those of us fortunate enough to attend the demonstration which accompanied the launch of the Prophecy, the answer became obvious within minutes. There is an indefinable 'something' about certain instruments: the Minimoog, the Mellotron, the Yamaha CS80, the Roland Jupiter 8, the Hammond C3, the Fender Rhodes... and the Prophecy quickly proved that it too has a great deal to offer: depth, delicacy, expression... The demo had huge Moog modular‑type sounds with multiple oscillators, detune, and rasping analogue filters with bags of resonance. There were analogue sync‑sweeps, more 'Emerson‑style' Moog emulations with the oscillators tuned in 3rds and 5ths, glitch‑free resonant filter sweeps, and acid synth‑basses with pitch‑bend and portamento. Bell‑like FM sounds were followed by analogue sounds modulated to emulate wave sequences. There were demonstrations of up/down arpeggiation that sounded like nothing so much as a Juno 60, and random arpeggiation reminiscent of a Jupiter 8. An uncannily realistic soprano sax solo was followed by a demonstration of the harmonic changes that you would expect to hear when a guitarist moves the position at which a guitar string is plucked. This then metamorphosed into an overdriven, distorted, screaming lead guitar. There was an uncanny bass guitar played using slap and hammer, as well as more traditional fingering techniques. A demo of tonguing and overblowing a Trombone was followed by a snatch of 'Amazing Grace' played on bagpipes which, as the 'virtual' arm pressure was released, had the drones decaying as the bag deflated. Finally there was the 'outro': an enormous lead synth solo with resonance, filter modulation, oscillators entering and leaving the mix for feedback effects, and just about everything else. An instantly recognisable snatch of the solo from ELP's 'Lucky Man' (originally played on a Moog IIIC) had everybody grinning. All very smooth, very powerful, very convincing. The Emperor was well and truly wrapped in his winter woollies.

If this sounds a bit overwhelming (and it was) you don't have to go far to convince yourself just how powerful and expressive the Prophecy can be. No further, in fact, than your local music emporium and the Prophecy's demonstration programs. These dramatically show off 16 of the factory programs — analogue synths, basses, brass, flutes, and others — and demonstrate the extremes of mood and expression that you can coax from the log and the other real‑time controllers.

Playing Techniques

This brings us neatly to the following question: can you simply plug in a Prophecy and expect it to sound like a genuine saxophone or a wall full of painstakingly programmed Moog Modules? The answer, I'm afraid, is no. Give a novice gut‑scratcher a Stradivarius, and he (or she) will still sound like a novice. In our case, and despite the quality of the Prophecy's sound generation, simply pressing down the notes will produce a sound rather like a synthesized saxophone, or a poorly programmed Moog. The reason is this: physical modelling has made it possible not only to reproduce single notes with realistic timbres and modulations — after all, a good sampler can do that — but also to recreate the nuances and sounds that occur within and during the transitions between those notes. So, if you want to sound like you're playing a particular instrument, you've got to play like you're playing that instrument. For example, the more competent your control of parameters such as 'air pressure' and 'embouchure', the more realistic any brass or reed model will sound. To put it another way (and here's a statement guaranteed to wring cries of dismay from some players) the better you play your synth, the better it sounds. And that, in the absence of a breath controller, means learning to control the log, the ribbon controller, the ribbon's pressure sensitivity, the two wheels, the velocity sensitivity, and the pressure sensitivity.


It's almost impossible to discuss the Prophecy in terms of any limitations. OK, so it's limited to seven sound creation methods — but that's still six more than almost any other synth ever released. Maybe the effects section is a little limited compared to, say, a Quadraverb, but then this is a monosynth, and not a piece of outboard equipment. Wait, I've found one — there's no breath controller! Then again, the Prophecy responds to and can route every MIDI controller to just about every parameter you can think of!

Taking things a little more seriously, there are three areas in which Korg could have made improvements — two concerning the hardware, the other to do with software. Firstly, the pressure exerted by the log's return springs is too high. While this might sound trivial, the Prophecy is performance‑orientated, and the response of the controllers should be as near‑perfect as possible. On production models, the moulding of the log will be slightly different to the prototype you see here (and much kinder to the fingertips), but my feeling is that the spring loading should be slackened off. Secondly, it seems a shame to limit the Prophecy to just three octaves. Sure, that was good enough for most monosynths, but real classics such as the Minimoog, ARP 2600, and even Korg's own 800DV had 44‑ or even 49‑note keyboards. Clavia and Yamaha seem to have learned the lesson (with their Nord Lead and VL1 respectively), and it's a shame to see the Prophecy limited in this way.

Finally, let's worry about the software — and, in particular, the initial impenetrability of the operating system. This is a direct consequence of the enormous flexibility of the Prophecy, and could be a serious limitation, at least in terms of players quickly and easily programming the sounds that they want. Korg could, and maybe should, have mitigated this by providing a better display. Two lines of 40 characters with no graphics simply aren't the right tools for such a detailed instrument. But... would potential purchasers have paid the extra £150 for a full‑sized screen? Such an increase would have taken the Prophecy well over the magic £1000 mark. Another solution would be for Korg to supply a software editor to run on a Mac, PC, or Atari ST. Unfortunately, although they have an editor that they're using to programme the factory voices, it only runs on an NEC computer with its own high‑powered DSP expansion boards. Whatever the answer is — even if it turns out to be a 6ft x 4ft wall‑chart — something should be done to make the power of the Prophecy more accessible. There are so many quality sounds crowded together inside its silver‑grey case that they are almost cracking the plastic to get out. And editing, once mastered, opens the doors to genuinely new sounds.


Oh my god! How can I summarise such an instrument in so few words? It will take years to plumb the Prophecy's depths. This review has barely scratched the surface of its capabilities, although it must be emphasised that nothing in the Prophecy is particularly arcane or impenetrable in the way that the DX7 was, it's just that there's so much of it. Anyway, here goes...

Though many have tried, no manufacturer has ever succeeded in wresting the King of Monosynths crown away from the Minimoog. But maybe, just maybe, Korg have cracked it. Analogue anoraks might complain about the digital parameter access editing, and argue that "it can't possibly be like the real thing" (whatever that means), but too many of them forget that the bottom line with any synthesizer is the sound. That was true in 1970, and remains so today. By that measure, whether emulating an analogue synth, a sax, or a bass guitar, the Prophecy stands up to the closest scrutiny. As for value for money, a 1970 Minimoog cost, at today's values, about £5,000. All seven synthesizers that comprise the Prophecy will set you back less than 20% of that. Indeed, they'll cost you little more than double the typical prices being asked for the rash of quirky 'retro' analogue monosynths that hit the streets during 1994 and 1995.

Stop messing around. Forget paying £1,000 for a 20‑year‑old Minimoog. Make your apologies to the guy trying to sell you a BassStation. Put your money back in your pocket. The Prophecy is in the shops now. Go grab your bank manager and knock him about a bit until he gives you another few hundred quid. Then go and get gob‑smacked like the rest of us.