As technology becomes more "digital" and music moves "back into analogue" a curious middle ground opens up between them - a middle ground occupied by Casio's VZ8M synth module.

AT ONE TIME Casio were known only for their watches, calculators and cheap 'n' cheerful home keyboards. Then in 1985, when Yamaha were already trailblazing the digital path with FM synthesis, the company took their first step into the world of "serious" hi-tech instruments with their CZ range of digital synths. The CZs became popular by providing a cheaper and more user-friendly variation on FM synthesis, using a custom form of digital synthesis known as Phase Distortion.

In the ensuing years, Yamaha have made FM more sophisticated, yet easier to use, and have provided FM instruments to suit every bank balance. And now that every synth manufacturer has gone digital, Roland, Korg, Kawai and Ensoniq have chosen to follow a different path from that trodden by Yamaha and Casio, each instead opting for their own method of combining sampled and synthesised sounds. What's more, the increasing power and decreasing cost of digital technology has allowed manufacturers to combine synthesiser, sequencer, drum machine and effects processor in one keyboard instrument, and the workstation concept has taken hold.

So, several years on from the CZs, where do Casio fit into this brave new world? Well, last year they introduced the VZ1 synth (reviewed MT, September '88) and 3U-high, 19" companion VZ10M rack-mount. These use iPD - interactive Phase Distortion - a more sophisticated version of their original digital synthesis system which, in conceptual terms, could loosely be considered as a user-configurable version of Yamaha's FM synthesis. Now the VZ8M is the latest and cheapest variation on the VZ theme, a 1U-high 19" expander which adds auto-panning but halves the VZ1/VZ10M's polyphony to eight voices and, due to its reduced dimensions, forgoes the generous displays of its companions in favour of a 2x16-character backlit LCD window.

Like the other VZs, the 8M has none of the abovementioned trappings introduced by other manufacturers. And just as Yamaha have stuck with FM, so Casio's iPD synthesis steers resolutely clear of the currently-popular combination of sampled and synthesised sounds. Yet while Yamaha may have flogged FM synthesis for all it's worth over the past few years, they've at least seen fit to keep the 'packaging" up-to-date - witness the user-friendly YS100 and YS200 synths, and the recent V50 FM workstation complete with onboard sequencing, drumkit section and effects processing.

Compared to other budget expanders such as Kawai's K1R and K1M or Roland's MT32 and D110, the VZ8M seems almost traditionally conceived (that's traditional as in early digital rather than analogue). But does that make it an unattractive proposition by today's standards?

STRUCTURES & MODES

CASIO'S iPD SYNTHESIS is based around the concept of eight sound Modules, each consisting of a DCO and a DCA, which can be configured in a number of ways. Instead of drawing on a variety of sampled and synthesised sounds, each Module's DCO can be assigned one of eight possible waveforms: a sine wave, five sawtooth waves and two noise sources.

Modules are paired into lines (1+2, 3+4, 5+6, 7+8), and there are three possible ways in which each pair of Modules can be combined: Mix, Ring Modulation or Phase. In addition you can specify External Phase on/off for each of Lines 3/4, 5/6 and 7/8, with the second Module in each Line being modulated by the preceding Line.

Those of you familiar with Yamaha's FM synthesis will recognise certain parallels here: the Modules can be thought of as operators which become carriers or modulators depending on the Mix, Phase and External Phase settings assigned to them. What this means is that, instead of selecting a predefined algorithm (to use Yamaha's terminology once again), you define your own algorithm, or configuration of Modules. Pressing the Module On/off button in Edit mode calls up a display of the current configuration in the LCD; you can also turn individual Modules on or off in this display by pressing the Program Number keys 1-8. As with FM, Casio's iPD synthesis doesn't have filtering in the traditional sense, but when you specify a Phase relationship for a Line, the first module is effectively modulating the timbre of the second, with its DCA shape controlling the timbre envelope.

By selecting Phase and External Phase for all Lines you can modulate the eighth Module with Modules 1-7. Or, at the other extreme, with all Modules set to Mix and no External Phase you can have eight waveforms per sound; while this means the basic waveforms are unchanged, you can detune waveforms against one another and apply a variety of other operations which can be used to change the waveforms even though you can't modulate them. You can define a large number of different configurations within these extremes, theoretically allowing a healthy variety of sounds. And in case you hadn't already realised, each of the VZ8M's eight voices can play a complete eight-Module sound, though reducing the number of active Modules doesn't increase the polyphony.

"The VZ8M's eight voices can play a complete eight-Module sound, though reducing the number of active Modules doesn't increase the polyphony."

The sound that you create using the eight Modules is known as a Normal patch. As well as the configuration of Modules, there are a number of other parameters which are programmable per patch. You can define a pitch envelope of up to eight stages which is common to all eight Modules, and specify envelope depth, a six-step keyboard follow envelope, and velocity control of pitch. A vibrato function acts as an LFO on the DCO, with a choice of triangle, saw up, saw down or square waves, and settings for depth, rate, delay and multi-trigger on/off. Usefully, the pitch of all eight Modules can be adjusted +/- two octaves in octave steps from one parameter.

A similar set of parameters can be defined for the DCA, only in this case for each Module individually (except for tremolo, which affects all eight Modules alike). You can also define for the eight Modules globally whether or not each of aftertouch, MIDI footpedal (controller number four), MIDI mod wheel and a further definable MIDI controller (in the range 12-31) will affect such features as vibrato depth and rate, pitch, amplitude envelope bias and tremolo depth and rate, and whether MIDI controller 64 will function as sustain, sostenuto or be disabled altogether. Meanwhile, the 8M's velocity responsiveness can be adjusted by selecting any one of eight velocity curves, including a reversed curve and "velocity off" curve.

Panning across the 8M's stereo outputs can be fixed (+/-15), controlled via the various dynamic MIDI control options mentioned above, or auto-panned according to user-definable rate and depth settings (this latter option is a new feature).

In addition to Normal mode, the VZ8M also has Combination and Multi modes. These allow you to combine up to eight Normal patches in a variety of ways. In Combination mode you can choose one of nine split/layer keyboard configurations, while Multi mode allows you to set up a multitimbral MIDI configuration for sequencer or guitar performance.

The Combination mode's nine key-assign configurations are as follows: 1+2, 3+4, 1+2+3+4, 1/3, 1/3+4, 1+2/3, 1+2/3+4, 1/2 / 3/4 and 12345678, where "+" is a layer and "/" is a split. If you're using the R/Mix line out then all patches will be sent from that out, but if you're using the stereo pair then the configurations are "split down the middle".

In split textures you can define the split points yourself, while for layers you can create velocity splits and positional crossfades between the relevant Normal patches. Additionally you can set the volume level of each patch, and individually delay the onset of each patch in a layer of up to four patches (useful for creating echo effects on an instrument which has no onboard audio effects processing).

Multi mode on the 8M allows you to select a Normal patch, MIDI channel, volume level and poIyphony for each of eight Areas. As the expander can't dynamically allocate its eight voices across the Modules, you have to allocate a fixed poIyphony to each of the Modules you want to use; therefore if you wanted to use all eight Modules, each Module would be limited to one voice. Admittedly this isn't a problem if you're using the 8M as an expander for a MIDI guitar, but for keyboard and sequencer applications it's a bit of a pain; I thought we'd finally got beyond such limitations, as most manufacturers nowadays provide dynamic allocation of voices.

Normal patches can be stored to their own memories, but you can also store them into onboard Operation memories along with Combination and Multi settings - the idea being that you can easily switch between different types of "texture" if they're all stored in one memory type. In fact, Combination and Multi settings have to be stored into the Operation memories.

"Casio's implementation of MIDI overflow mode allows you to link up to eight VZ8Ms for 64-note polyphony - though I'm not sure who'd want to do that."

The VZ8M has 128 preset Normal patches and 128 preset Operation memories, with a further 128 of each accessible from a ROM card which plugs into the slot on the expander's front panel. For your own programming purposes Casio have provided 64 Normal and 64 Operation memories onboard the 8M, with a further 64 of each accessible off RAM card.

The 8M's internal memory can also be transferred via MIDI SysEx, either sectionally or as a full memory dump (which takes a lengthy 25 seconds). Incidentally, Casio's implementation of MIDI overflow mode allows you to link up to eight VZ8Ms for 64-note polyphony, though I'm not sure who'd want to do that.

Finally, bearing in mind that Casio also produce MIDI guitars and MIDI wind controllers, it's not surprising that they've included special Guitar and Wind performance modes along with the standard keyboard performance. In the case of Wind mode, for instance, the 8M's aftertouch sensitivity is automatically adjusted to suit the output of, presumably, Casio's digital horns.

SOUNDS

THE CRUNCH COMES with how the 8M actually sounds. Well, overall I'd say clean, thin, bright, metallic, sparkling, crystalline, hard-edged... very "digital", with all the implications that that word had in the early days of digital synths, when FM and PD synthesis were synonymous with the digital sound. The 8M is also capable of producing some nicely rounded, warm-edged sounds which nonetheless have a sharp, clean quality, such as some of the bass, vibes and string-pad sounds. The preset sounds include typically digital bright, tinkly electric pianos, clangorous bells, gamelan-type clangorous percussion, "icy" atmospheric sounds, clean and polite (as opposed to grungy) electric organs, metallic tuned percussion, some cutting but not exactly fat lead sounds, a mixture of hard percussive and hollow metallic bass sounds... You get the general idea, no doubt.

The VZ doesn't have the sort of all-round competence that we're coming to expect from today's sample-based synths, and on the whole it's not the instrument to go for if you want imitative sounds or expansive pad-type accompaniments, but it does have a particular quality of sound which can be exploited very effectively in the right context (for instance, it can be quite techno-sounding in a Derrick May style). And whereas the trend in synths is towards a sample/synth hybrid which provides an ever-greater number of source sounds that are complete in themselves, the VZ's uninspiring source material and flexible programming possibilities make it more of a programmer's instrument.

VERDICT

A FEW YEARS back, the VZ8M would probably have been lauded for the new quality of digital clarity and brightness it brought to synthesis, and programmers would have worked hard to wring all manner of imitative sounds from it, with varying degrees of success. But by today's standards it sounds, well, dated (early digital period, circa 1985).

Given the much greater sonic competence of today's generation of digital synths. I don't think I'd choose the 8M as a first expander, but perhaps as a second (or even a third) which could selectively add the particular kind of digital bite and metallic edge that it's well suited to delivering. And I wouldn't rely too much on the existing sounds but delve into the programming to shape sounds more precisely to my own requirements.

At a time when the trend is towards increased polyphony, I'm not sure that opting for reduced poIyphony on the VZ8M was a wise move on Casio's part, especially with the fixed polyphony of the Areas in Multi mode. However, as I mentioned earlier, these factors shouldn't really trouble MIDI guitarists or MIDI wind players. For keyboard performance and sequencing purposes, I would be inclined to go for the 16-voice VZ10M, which after all only costs £100 more than the 8M.

The synth world has developed rapidly over the past couple of years, and I can't help feeling that Casio have got somewhat left behind in the rush. But we've long since learned that old synths never die, they just bide their time till they sound fresh again, so no doubt the VZ range will find its own niche.

Price £499 including VAT

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