No doubt about it, the new DX5 fills a yawning gap in Yamaha's FM polysynth line-up. But does it have enough accessible facilities to steer musicians away from buying a modular DX7-based system from the same company?

A couple of months back, I finished my review of the budget DX21 poly by saying that Yamaha had scarcely put a foot wrong, in terms of hi-tech product planning, since they produced their first range of programmable FM synths in 1983. That range comprised the DX9 (the model the 21 replaces), the ubiquitous DX7, and the DX1, a handbuilt, prestige machine with a suitably prestige price-tag: just under £10,000. What was missing then was something that bridged the gap between the accessibility of the 7 and the higher performance (in all respects) of the flagship machine. It remained missing until a month or so ago, when Britain received its first bulk shipment of a new polysynth called, logically enough, the DX5.

The 5 turns out to be the essence of a DX1 in most important areas - though it lacks some flashy front panel displays, a weighted keyboard, and that holiest of synth player's performing grails, polyphonic aftertouch. Working down from the DX1, the newcomer's sub-£3000 RRP makes it look incredibly good value for money. But it's more realistic to judge its economic worth in relation to the DX7. In fact, the DX5 is essentially two DX7s combined in one instrument, something that wouldn't bode too well for its value for money rating if it didn't have sundry other goodies to boast as well.

First of these sundries is sturdiness, something the DX7 has a little of but the DX5 has in abundance. Being this big and heavy (just look at the pictures) doesn't do much for the synth's portability, but it does mean it'll take a few studio or gigging knocks before throwing in the towel and losing half its memory.

Turn the thing on, and the DX5's sound quality is instantly recognisable as FM. The structural similarities between this synth and its Yamaha brethren mean that anybody who's ever played with an older machine will feel comfortable with the DX5 almost straight away.

Appearance-wise, the DX5 looks familiar too. Really, it's a tasteful combination of a number of elements from other Yamaha keyboards (mainly the DX7 and DX1), and succeeds in looking rugged, modern and professional all at once. Something old, something borrowed, something blue (or purple, or green).

The DX5's keyboard has a six-and-a-quarter-octave (E-to-G) span, and is capable of responding to attack velocity and channel aftertouch. Whilst its action won't appeal to anyone who likes a firm touch response, it has a light, smooth travel most of the office staff found rather pleasant to play. And with twice the synthetic capability of the DX7, you'll not be surprised to learn that the DX5 has a full 32 notes' worth of polyphony - which must be something of a record in the synth world.

You'll also not be surprised to learn that, with two FM tone generators at its disposal, the 5 features Dual and Split modes of operation - which still leaves you with 16-note polyphony for Dual playing and 16 notes either side of a split (split-point is fully variable).

The voice memory is divided into two 'channels' (A and B), each of which has four banks of eight voices. In Single mode, both FM tone generators are dedicated to the same voice, giving the above-mentioned 32-note polyphony. In Dual and Split modes, each generator is dedicated to a different voice, one selected from channel A's memory and the other from channel B's — so each voice has the 16-note capacity of the DX7.

As the DX5's voice parameters are the same as the DX7's, there seems little point in going over what must be familiar territory to a lot of you reading this review. Taking each voice channel individually, the sonic capabilities of the DX5 are neither more nor less than the DX7 - though in the natural way of things, the new machine's factory sounds reflect the increased experience Yamaha's programmers have accumulated in working with FM.

There's a particularly attractive selection of keyboard sounds (pianos, electric pianos and electric grands included), while strings and brass also come across strongly. There's the usual array of delicate struck and plucked voices (including an effective jazz guitar-type sound), some 'standard' percussion sounds such as snare, cymbal and tom toms that come out with varying success, and the usual array of effects such as bombs dropping, (electronic) birds tweeting, and even the sound of traffic (a bit of a disappointment, this one, as a couple of car horns don't really constitute a traffic jam worthy of inclusion in a Renault car commercial).

In terms of pure sonic capability, the DX5 is the equivalent of two DX7s. And where it scores is in the facilities it provides on top of that basic capability. First off, it has 64 onboard performance memories and the ability to read 64 more off cartridge. Performance memories were a feature of the DX1, but have more recently and noticeably made an appearance on the DX21 poly. But whereas each of the 21's performance memories is limited to storing voice position pointers and voice mode, and performance controllers are voice-programmable, the 5 includes performance controller function parameters in its performance memory - a much more flexible approach. Another nice feature of the 5's performance memories is that they can access voices from both the internal and cartridge voice memories, something that makes their application possibilities splendidly open-ended. And even though they aren't voice-specific, the 5's performance memory parameters are programmable for each voice channel. So in Split and Dual modes each voice has its own controller allocations. This means you can program the sustain pedal or pitchbend, for instance, to be functional on one voice but not the other.

Together with sustain and pitchbend, there are parameters governing portamento, modulation, breath control and aftertouch. Also included is a useful 'output level attenuate' function which allows you to balance voice levels in Split and Dual modes (some voices are inherently louder than others). You can also accomplish this using an A/B balance slider on the front panel, but it's obviously convenient to be able to preset levels. And that's the thing that characterises the DX5 most of all: convenience.

A further useful performance memory function comes under the auspices of MIDI, and goes by the name of 'source select'. It allows you to define either the DX5's keyboard or an incoming MIDI channel as the controlling source for each voice channel (the Oberheim Matrix 12 operates something similar). This is particularly handy in Dual mode, where you can have two voices spread over the entire keyboard, with one controlled from a MIDI sequencer while you play the other from the keyboard.

One of the 'improvements' an upmarket synth should have over its cheaper brethren is in front panel accessibility - a consideration that's increased in significance since digital control made parameter access a maze rather than a motorway. The DX5's bid for easy access takes the form of a larger LCD (2 rows by 40 characters - and backlit, thankfully) and a healthy array of buttons in various groupings across the lower half of the front panel. Generally speaking, these buttons operate at two levels: voice and performance memory selection at one level, edit and function parameter selection at the other. Again, it's an approach that'll be familiar to every DX owner. Each button has a small built-in red LED to indicate when it's activated, but these only function at the voice/performance memory level.

At the other level, every edit parameter is given its own button, and each of the six operators has its own select and on/off buttons (again with their own LEDs). The increased size of the LCD allows all the edit parameters to be accessed from just five displays - with each display cramming in up to 12 parameters in PPG fashion. This easy access and the ability to view a number of parameters at once makes voice editing an appreciably less laborious task than it is on the other DXs. And that has to be good news.

Spread across the upper half of the panel are the algorithm, EG and keyboard level scaling diagrams carried over from the DX7, and a Function Job table that effectively 'maps onto' an array of performance/function buttons further down the panel. Quite what lies behind Yamaha's fascination with 'Jobs' (they've previously made an appearance on the company's QX1 and QX7 sequencers) I'm at a loss to explain. In the present context, they're merely function parameters, with up to three of them assigned to each button in the aforementioned array. Cross-referencing between the table, buttons and LCD can be a bit confusing at first (especially when you have to deal with 'subjobs' as well, which you have to if you're mucking about with the MIDI functions), but you soon get used to it.

Edit and Function value changes are made using the evergreen data slider and ± selectors, and the 5 follows the DX21 in making individual Edit buttons double as incrementor buttons.

"Sounds - There's an attractive selection of keyboard sounds in the factory line-up, while strings and brass also come across strongly."

The DX5 has two cartridge ports on the right of its front panel, one for each of voice channels A and B. These can take 64-voice ROMs and 32-voice RAMs a la the DX7, and slot A can also take ROM and RAM Performance cartridges. Obviously, if you're accessing a Performance cartridge you can't access sounds from voice cartridge A - not serious, but a separate Performance cartridge slot would have given total flexibility.

Neatly, Yamaha have provided a comprehensive set of memory management commands for shunting your voice and performance data around and between the internal and external memories.

The 5 comes complete with two ROM voice cartridges and one ROM performance cartridge, giving you 128 voices and 64 performance memories. Of course, as there are 64 voice and 64 performance memories on board the 5, you have a 'best case' situation of instantaneous access to 192 voices or 128 performance memories - and that's before you need to get into RAM cartridges.

One happy consequence of the compatibility in voice structure that exists between the DX1, 5 and 7 is that ROM and RAM voice cartridges are compatible across all three instruments. Thus, if you've already built up a voice library for your DX7, you can use it on the DX5 and even combine your voices using the 5's Dual and Split modes.

This is going to be good news in studios - keyboard players can bring in their own DX7 sounds and take advantage of the DX5's facilities just by plugging in their cartridges. And for anyone considering trading in their DX7 for a DX5, the knowledge that you don't have to lose your valuable DX7 voice library in the process must make the trade-in a more attractive proposition. (Another possibly happy consequence for DX7 owners is that the DX5 voice ROMs will work with the DX7, but that's a different story.)

A glance at the DX5's rear panel reveals sockets for portamento, sustain, modulation and volume sockets; stereo audio outs and a mix (mono) output (on both phono jacks and XLRs); and one each of MIDI In, Out and Thru. Breath controller input and stereo headphone output (the latter with its own volume control) are to be found in front of the pitchbend and modulation wheels. Conspicuous by its absence is a cassette socket - because when it comes to storage, the 5 is cartridge and MIDI only.

MIDIwise, the DX5 can be set to receive on all channels (ie. Omni on) or on any of the 16 channels individually, and separate transmit and receive channels can be set, too. The two onboard voice channels (let's not get confused here) can also be set to receive on different MIDI channels, which is useful if you're in Dual mode, say, and want to run one voice only off a sequencer. There's also a master MIDI on/off parameter.

The DX5 is also capable of transmitting and receiving MIDI mode changes - but it won't magically transform itself into a multitimbral synth if you send it Omni off/Mono codes, I'm afraid.

Yamaha have also given the DX5 the ability to send MIDI Start, Stop and Continue codes for sequencer and drum machine control - a nice feature which makes a lot of sense and deserves to become a more common feature on synths in general. We shall see whether the 5 is going to set a precedent here. The facility would have been more usable, though, if Yamaha had provided dedicated front-panel buttons for instantaneous access, rather than burying selection among the general Function parameters.

Anyway, MIDI System Exclusive facilities allow you to dump single voice and performance data, all voices in channel A, all voices in channel B, and all internal performance data over MIDI. The aforementioned compatibility of voice data suggests that in addition to MIDI transfer from DX5 to DX5, you should be able to transfer between DX5 and DX7. And a quick test with office DX7 MIDI'd up to guest DX5 revealed that it does work. Single-voice data and 32-voice data (A and B in the case of the DX5) were successfully transferred in both directions. But more interestingly, perhaps, any DX7 voice editing or voice storage program should logically work with the DX5 as well.

What's lacking on the MIDI front? Well, separate MIDI transmit channels for each voice channel would have been a good idea, and instead of grouping MIDI data into basic and other event data for MIDI communication on/off, it would be preferable to have individual on/off functions for the various parameters. And seeing as Yamaha obviously realise the value of making performance parameters programmable, it's a shame they haven't extended that programmability to the DX5's performance-oriented MIDI settings. Now that really would be comprehensive.

The DX5 is probably the last variation on what is by now a well-worn formula. Certainly it offers nothing strikingly new to the marketplace, and when you consider that it's essentially the DX1 in a slightly different guise, you get some idea of just how old its design priorities are. When the DX1 first came out, split and dual keyboard modes were a bit more unusual than they are now, for instance, but more recently Oberheim, working in the same 'upmarket' price category as the DX5, have shown more imagination with the zone system incorporated into their Xpander and Matrix 12.

Which is not to say that Yamaha aren't capable of applying imagination to this area themselves. Their KX88 controller keyboard (reviewed in E&MM May '85) implemented some of the most inventive MIDI control facilities currently on offer, and I can't help wishing that some of the KX88's MIDI control flexibility had rubbed off on the DX5.

But whatever you do, don't underestimate the DX5. There's the sheer sonic power of two DX7s in one instrument, the ease with which you can access a large array of voices, the (relative) ease with which you can edit voices, and the particular control the performance memories provide. The DX5 is a joy to play and a joy to use in the broadest sense.

Overall, the convenience of its design format means it's probably preferable to either a DX7+DX7 or a DX7+TX7 combination, at least so long as money isn't your most important consideration.

Yet the crux of the matter is whether it's really worth having this sort of FM sound potential. Fact is, you've got to be infatuated with FM to want to spend three grand on the DX5, especially if you already have a 7 kicking around. Because no matter how attractive the proposition sounds, having the synthetic abilities of two DX7s isn't going to make too much difference to your final sound unless you're a confident and experienced FM programmer.

If you aren't, and you want some expansion in the sound department over and above what a DX7 can provide, you're better off looking for an analogue add-on.