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Korg DS8

Digital FM Synthesiser

After last month's preview, Simon Trask gets to grips with FM's friendlier face. Can simpler programming compensate for the deficiencies of four-operator sound?

At last, a machine that produces sound with FM synthesis, yet incorporates a familiar, analogue-style programming system. Does the hybrid really work?

FOR A LONG time now, the cry from musicians has been that FM synthesis, wonderful though it may sound, is too difficult for all but the most dedicated to program. Yamaha's DX7 has been accused of encouraging preset mania - though the huge library of sounds that have been programmed by those dedicated souls mean there are a lot of "presets" around.

Essentially, the programming problem seems to break down into two interlinked causes: conceptual confusion (nobody really knows what all the building blocks are or what they're for) and digital access fatigue (too much button-pushing, not enough feedback). Korg's new FM synth, the eight-voice DS8, addresses both of these problems. It superimposes a different programming architecture and terminology on the real workings of FM, and comes up with a programming system which, from the word go, is much, much easier to work with.

You can tell, as soon as you lay a finger on the DS8, that this is an FM instrument through and through. Flicking through the 100 onboard sounds reveals that familiar sharp, transparent, metallic quality with which we have all become so familiar. The DS8 offers no real surprises in the FM department - and it is the Mk1 version of FM, not the improved version to be found on Yamaha's DX7II and TX81Z.

Korg have concentrated on providing a wide range of sounds: pianos, electric pianos, organs, acoustic and electric basses (including the inevitable slapped bass), strings, lead synths, trombone, trumpet, flute, clarinet, lead synth, jazz guitar, percussive sounds such as vibes and marimba, and a variety of sound effects such as wind, rain, water drops and birds. There are also a few patches which offer combined sounds, such as electric piano + strings and bell + brass.

Korg have also given the DS8 dual and split keyboard modes (which they confusingly term layer and double). Split mode additionally allows two sounds to be overlapped over any section of the keyboard, and you can allocate a number of voices to each side of the split (eg. 3+5 or 2+6), while a multi-timbral mode allows up to eight separate patches to be played remotely from a sequencer within the overall polyphony of the synth. These modes, together with your choice of patches, can be arranged in what Korg term "combi-programs", ten of which can be stored onboard the DS8.

And, determined to give their new synth a contemporary flavour, Korg have included onboard programmable effects such as delay, flange and chorus (but not reverb) which are a definite bonus - flange and chorus in particular really fill out a sound.

As for the keyboard itself, it's of the five-octave, weighted plastic variety, and in keeping with most of the competition, is sensitive to both attack velocity and channel aftertouch.


THE DS8 ADOPTS what seems, on the face of it, a familiar programming system: two oscillators each with their own four-stage timbre envelope and four-stage amplitude envelope, plus a four-stage pitch envelope and an LFO (or Modulation Generator, in Korg's terminology) which are common to both oscillators.

Oscillator 1 offers a choice of sawtooth, square, bright sawtooth and bright square waveforms, while oscillator 2 offers sawtooth and square waves but also allows you to select crossmodulation; again, in Korg's terminology, oscillator 1 modulates oscillator 2, and so creates no sound of its own. You can change the pitch of each oscillator individually, but this process steps through the harmonic series rather than octaves or semitones, and the two oscillators can be detuned. A keyboard-tracking parameter alters the brightness of the sound as you move across the keyboard (more at the top, less at the bottom).

The timbre EG section consists of a master timbre "level" in addition to the timbre envelope, and an intensity parameter which determines the intensity of the timbre modulation by the timbre EG within the range determined by the master level. And there's another keyboard-tracking parameter which shortens the timbre envelope as you move up the keyboard, and lengthens it as you move down the keyboard.

The amplitude EG section includes master level (allowing you to balance the volumes of the two "oscillators") and envelope rate settings together with keyboard tracking; obviously, intensity doesn't figure here. Other timbrally-based parameters are spectrum (which produces a resonance-type effect) and ring-modulation.

Of course, the timbre section isn't a filter section, even though there are broad similarities in effect. What we are dealing with here is FM synthesis - Korg have merely superimposed a more accessible and intuitive structure on the real FM architecture of algorithms, operators, carriers and modulators. In fact, one of the fascinations of the DS8 is the way that the two structures don't quite mesh in sonic terms. FM synthesis won't produce the same results as analogue synthesis (from which Korg have borrowed the DS8's programming structure) because the building blocks don't function together in the same way. Result? The internal organisation (which ultimately controls the sound of the DS8) subverts the external organisation, which makes for a refreshing angle on programming.

It is possible, more or less, to understand the DS8 in Yamaha's terms - and experimentation using a DX7 side by side for comparison suggests that the DS8 employs two four-operator FM algorithms (numbers 4 and 5 on the DX9, but seemingly minus the feedback loop on 5; the second algorithm is selected by choosing cross-modulation for oscillator 2). And indeed, the DS8 does sound more like a DX9 than a DX7 - though beyond making that generalisation, it would be a mistake to tie the DS8 down to any one of Yamaha's DX instruments, because it has its own identity and character. Still, one undesirable feature of FM synths up 'til the DX7II is, unfortunately, also evident on the DS8: digital noise on bassy sounds.


KORG'S "NEW' PROGRAMMING system isn't the only way in which their design team has made FM more accessible. There are also a number of ways in which you can make very quick alterations to a sound during performance using dedicated front-panel controls. For a start, you can cycle between oscillators 1, 2 or 1+2, which in effect gives you control over the two sound components that can make up a single voice on the DS8. The effectiveness of this obviously depends on the sounds you have programmed, and if you're using cross-modulation you will get no sound from oscillator 1 at all.

Other dedicated buttons allow you to switch velocity, aftertouch, portamento and multi-effects on and off, and to cycle around the various multi-effects without having to go into edit mode. These performance features are applied to both oscillators in a single patch, and to both patches in dual and layer modes.

But the most useful performance controls (and also, perhaps, the most unusual) are the single timbre and two envelope sliders. While the former controls the timbre of both "oscillators" in a patch (producing an effect roughly equivalent to filtering, ie. brightening or darkening a sound), the latter control the overall volume envelope of each oscillator. The changes that these sliders make are not absolute, but relative to the parameter values set in the patch memory - which makes them much more flexible in practice. It's also worth noting that using cross-modulation changes the effect of the timbre slider and of envelope slider 1, because "oscillator 1" now assumes a timbral role (in FM terminology, it becomes a modulator).

"Korg's programming system isn't the only way they've made FM more accessible; you can also make quick alterations during performance."

Taken together, these features make a vital contribution to the character of the DS8, introducing a welcome degree of performance control and flexibility.

A more familiar Korg performance controller is the joystick, which can be moved in four directions: left and right control pitch-bend up and down (the range of bend can be set from 0-12 semitones), while up controls pitch modulation (vibrato) and down controls amplitude modulation (tremolo) and timbre modulation (wah-wah). Move the joystick diagonally, and you combine pitch-bend with these other effects.

Going back to the timbre and envelope sliders, these are intended to be performance-only controllers; any alterations made during performance are lost when you enter edit mode, where the current set of patch parameter values (edited or not) take over. What's more, the timbre and envelope sliders have no effect in edit mode, either.

In some ways this is a sensible approach for Korg to have adopted, but it does ignore the fact that the timbre and envelope sliders are very effective editing controls; you may well want to store the results of your manipulations or go into edit mode and fine-tune them. Instead, you have to hunt around in edit mode for the right parameter settings to recreate the sound that you created in an instant with the sliders.


GOOD NEWS, THOUGH, lies in the fact that editing sounds on the DS8 (in fact, doing just about anything on the DS8) is greatly aided by a 2X40-character backlit LCD, which allows you to see several related parameters at the same time. Left/right cursor switches allow you to step through the parameters, while familiar increment/decrement buttons and a data entry slider take care of parameter value alterations. Thankfully, this sort of large and informative window display is becoming a common feature on synths and samplers nowadays.

The DS8's parameters are listed on the instrument's front panel and are grouped under three headings: function, voice parameter and combi parameter, each with its own selector button. With the numeric keypad under the LCD window, this listing makes it easy to find your way around the instrument and to familiarise yourself with the features it has to offer.

There's no denying that the DS8's line in intuitive, user-friendly sound creation means you could build up a patch library quite quickly. That's a good thing, because not surprisingly, the wealth of sounds which exists for Yamaha's FM instruments can't be loaded into the DS8. And the DS8 gives you instant access to a large number of sounds once you've created them - up to 400 patches and 40 combi-programs can be stored on a credit-card RAM, which together with the onboard complement means that you can call on up to 500 sounds and 50 combi-programs with no cartridge swapping.

One point about combi-programs is that you can't combine internal and external patches. But it's easy enough to transfer individual patches between internal memory and cartridge, as well as transferring complete banks of 100 patches and 10 combi-programs.

The DS8 offers a useful range of parameters for taking advantage of the keyboard's dynamic sensitivity. You can determine velocity response for each of the timbre and amplitude envelopes in a patch, and aftertouch response for pitch modulation generation, timbre level (for both oscillators) and amplitude level (for each oscillator). Sadly, you can't invert the velocity or aftertouch response - so no switching or crossfading of sounds.

There's a choice of polyphonic and unison keyboard performance modes. Unison mode stacks up all eight voices to play a single patch, and offers you the ability to choose single- or multi-triggering and to detune the voices - a good way of creating a powerful sound. Korg haven't forgotten that old faithful portamento, either, which is programmable for each patch and can be switched in and out from a dedicated front-panel button.

The keyboard itself is a particularly effective compromise between synth-style and piano-style: plastic keys and medium travel, coupled with a modestly weighted action which allows you to "dig in" more than you can on some synth keyboards. It's certainly one of the most pleasing synth keyboards I've played in a long while.


A SIGNIFICANT FEATURE of the DS8 is its provision of onboard digital effects. Korg were one of the first manufacturers to put patch-programmable effects on a synth - you'll no doubt remember the programmable DDL on their DW8000 and Poly 800 MkII synths.

Today, the DS8's "multi-effects" section is slightly less sophisticated (but more friendly) than a full-function DDL, yet still allows you to program any one of delay (manual, long or short), doubling, flanger and chorus effects for each patch and combi-program. These can be switched in and out from the synth's front panel. There's no onboard digital reverb, but it's worth bearing in mind that you could buy a DS8 and a professional-quality dedicated reverb unit (such as Korg's own DRV2000 or the Ibanez SDR1000+) for the price of a synth with built-in reverb.

One irritation that I encountered on our review model is that when you call up a patch or combi-program which uses any one of these effects, there's a delay of a couple of seconds or so (sometimes less) before the effect actually comes into operation. By any reckoning, that's one built-in effect too many.

"You can't have a lead synth sound with long delay and a string sound with chorus - but you can have the long delay on the lead synth sound only."

Long delay offers a delay range of 105-729msecs plus programmable feedback level and effect level, while short delay offers a range of 20-88msecs and similar feedback and effect levels. Doubling, flanger and chorus are useful effects, but to these ears they don't possess the richness that you might expect from the same treatments produced by a dedicated delay line.

While each patch can have its own effect, the DS8 is capable of generating only a single effect at a time. This means that when you select double, layer or multi modes you have to make a couple of choices: which patch's programmed effect you want to use and which patch(es) you want the effect to operate on. What this means is that, for instance, in double (split) mode, you can't have a lead synth sound with long delay and a string sound with chorus - but you can decide, say, to have the long delay on the lead synth sound only.

A similar restriction applies with multi mode, and it's worth noting that, although you have access to up to eight different sounds when using the DS8 in conjunction with a sequencer, these sounds aren't totally independent. Just as the DS8 can only generate a single effect at a time, only a single set of controller assignments and a single set of Modulation Generator (LFO) assignments can be implemented by the synth. You can choose which patch will be the source, and turn the effect on and off for each patch individually.


BEARING THIS IN mind (and the same sort of thing applies to many multi-timbral instruments), let's consider what multi mode does allow you to do. You may remember from last month's In Brief that multi mode allows up to eight sounds on the DS8 to be played at once. Each patch can be assigned its own MIDI receive channel (1-16) and number of voices (within the eight-voice limit - there's no dynamic allocation of voices). You can play any one of these patches from the DS8's keyboard (within the assigned polyphony) by setting the synth's MIDI transmit channel to the receive channel of the relevant group.

For instance, you can play (and perhaps record) a monophonic lead synth sound on the DS8's keyboard while an external sequencer plays back a monophonic bass line and a four-voice chordal string part - and you'll still have two voices free for other parts.

A further useful feature of double, layer and multi modes is the ability to pan each patch to either left, right, or equally to left and right (centre) audio outputs, enabling sounds to be processed individually once they're out in the big wide world of audio.

In detail, the DS8 allows you to perform the following MIDI switching functions: select master transmit/receive channel, omni on/off, local on/off, active sensing on/off, patch change on/off, controllers on/off and System Exclusive on/off.

MIDI System Exclusive communication allows all 100 internal patches and combinations to be transferred in bulk. Individual patch data can also be sent over MIDI by selecting the relevant patch (as on the DX7, you need to have System Exclusive enabled to do this), and overall, the arrangement should make life fairly simple for those of you who want to use an all-purpose MIDI data storage device or equivalent software program. At the same time, Korg have actually provided a fairly sophisticated System Exclusive implementation (with full details in the manual), which software developers will be able to make use of for the usual patch editor/librarian programs for computers.

The DS8's rear panel offers MIDI In, Out and Thru, stereo and headphone outputs, a sustain pedal input, a dedicated program up input and assignable footpedal and footswitch inputs. The footswitch can be assigned to select program down, oscillator select (1, 2 or 1+2), velocity on/off, multi-effect on/off, aftertouch on/off and portamento on/off. The footpedal, on the other hand (foot?), can be assigned to control MIDI volume, timbre (equivalent in effect to the front-panel timbre slider), pitch modulation or timbre modulation.


IT WOULD BE all too easy for a cynic to dismiss this synth. FM has been with us for a long time, and thanks to Yamaha, there is an abundance of FM instruments in the marketplace.

The competition is stiff, with Roland's D50 just arriving in big numbers, the Ensoniq ESQ1 still selling well, and Elka's sophisticated EK44 (which also delves into FM territory) starting to win a lot of friends - though Korg's synth is the cheapest of all these.

So why bring out another FM synth? Obviously, Korg's intention is to provide an easier way of manipulating FM sounds, and the DS8 succeeds in doing this admirably. The combination of performance-based edit controllers and a more accessible editing system gives FM a new dimension, and makes the DS8 an instrument you could get attached to quite easily. Creating and altering FM sounds is no longer a chore - and as a result, the true sonic variety of FM reveals itself much more readily.

This is not to say that the DS8 brings a new quality to FM synthesis - the strengths and weaknesses of the system per se remain the same as ever. But despite what some people would have you believe, there's still plenty of life in FM.

The DS8's factory sounds don't tell the full story - they won't bowl you over if your ears are jaded, but they do provide a good range of sounds to work from. And unlike much of its competition, the DS8 has genuine charm as well as versatility - as long as you look beyond the presets. Which, funnily enough, is exactly what the machine encourages you to do.

Price £999 including VAT

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Also featuring gear in this article

Previous Article in this issue

MIDI Time Code

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Brave New Science

Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - Jul 1987

Donated & scanned by: Mike Gorman

Gear in this article:

Synthesizer > Korg > DS8

Gear Tags:

Digital Synth
FM Synth
FM 4-Operator

Review by Simon Trask

Previous article in this issue:

> MIDI Time Code

Next article in this issue:

> Brave New Science

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