If a Yamaha FM synthesizer fell off the back of a lorry and landed in your lap, it could hardly represent better value for money than the DX21 does at ordinary retail prices. Because this is Yamaha's new budget synth, a successor to the DX9 and one which is destined to sell in vast quantities to players from all levels of the musical game. To see how Yamaha have done it, read on...

No Compromise

The DX21 makes very few compromises to get below the magic £700 barrier, and those it does make are already familiar from the DX9. Four FM operators rather than the DX7's six, memory dump to cassette rather than cartridge, and no velocity sensitivity — which means that the DX7 will remain for some time as the professional's choice in the FM synth field. But unlike the DX9, which could be described by a list of omissions from the DX7, the new synth has some tricks of its own concealed up its digital sleeve. These include keyboard split, velocity sensitivity over MIDI, an improved MIDI specification, unusual memory facilities, a stereo chorus and lots more. Let's look at the basic layout of the DX21 before we get onto the juicy details though.

The DX21 is highly compact, due to the fact that the pitch bend and modulation wheels have been placed on the top panel rather than to the left of the keyboard. This shouldn't be too much of a problem in playing, and because of the very low profile of the synth there's nothing to catch your fingers on at either end of the keyboard as you're playing. The all-metal casing maintains a reasonable sense of weight, and the keyboard has a full five octaves of standard-sized keys with a decent playing action. Ticks and gold stars all round so far.

There are three main sliding controls for Volume, Balance and Data Entry, and the 32 memory select buttons are of a low-profile type with definite click action, a great improvement over the rather squashy membrane switches of the DX7, and there's a smaller bank of similar buttons to the left of the LCD display which access various memory and keyboard modes.

Sounds marvellous

The DX21's sounds are basically similar to the DX9's, since each has voices comprising four FM operators; clear, precise, digital and cutting. But the exciting bit about the 21 is that it can play in split (2 x 4 note poly) or Dual (4-note Poly) modes as well as Single (8-note poly) mode. This means that you can play two different sounds either side of a programmable keyboard split, or layer two sounds together and detune them to any degree using (no prizes for guessing) Dual Mode Detune.

The combined effect of detuning and the stereo chorus, which is a simple On/Off affair accessed in the Function mode, is to potentially take the DX21 far from the clean, clinical sounds of the DX7 and DX9. Strings can be smoother, brasses can be more lifelike, and the whole repertoire of sounds is much expanded. The 21's memory facilities exploit this fact; as well as the 32 RAM memories which you can edit, re-store and dump to tape, there are 128 hidden ROM memories which contain sixteen banks of eight sounds such as pianos, basses, effects, keyboards and so on. These can be called up at any time (remembering to save your important RAM sounds to tape before over-writing them) in sets of eight, and can be edited and stored in RAM memories if desired. However, you won't change the original ROM sounds, and it's nice to know that there's a considerable bank of decent presets available to you at any time.

Editing sounds is more or less the same as on the DX7 and DX9. The LCD display has more labelling around its outside edge so that some of the functions are more understandable, and there are small changes in the logic of sound editing — for instance, if you select a parameter in Function mode you can alter its value upwards, or toggle it on and off, by continuing to press the appropriate selector button. This saves moving over to the data entry controls, and the saving of one keystroke can make all the difference if you're heavily into editing and reprogramming sounds.

New facilities in the Function mode include MIDI transmit and receive channel select, which are quite independent and include the Omni (all channels) mode on the receive function. MIDI functions can be switched on or off and Key information is always sent when the MIDI port is enabled. You can choose whether or not the DX21 responds to patch changes, key velocity, modulation, breath control, portamento and data entry from outside, and if any envelopes are patched to controllable parameters in a patch, these can be controlled by velocity information coming into the MIDI port.

Let me expand

This makes the DX21 ideal as an expander for a DX7 or other velocity-sensitive synth, or as a peripheral for a MIDI sequencer being programmed from such a synth. So the DX21 will sell to the professional as a cheap source of velocity-sensitive FM voices, and to the almost beginner, perhaps as a move up from a Casio or other portable, as a relatively inexpensive but professional sounding synth with the economical tape dump method of saving sounds.

As we mentioned, the LCD display has additional functions marked around its outside edge, and one of these is Bend Mode; this can go to Hi (only the top note held bends), Lo (only the bottom note) or K-On (all notes bend). You can also choose to bend only notes held on the keyboard while those sustained by the rear-panel Sustain footswitch are left alone.

We'll look at the rear panel in a moment, but the DX21 has one other significant improvement over the DX7 and DX9 — the provision of individual Performance Memories for every patch. Poly/Mono mode, Portamento speed, Breath Control Response and so on are all programmable and can be called up together with one or two sounds and a split point in a Performance Patch, of which there are 32 altogether. On the DX7, once you'd programmed a portamento speed for a sound, for instance, you were stuck with it on every other sound; on the DX21, your String Bass is handily monophonic and has Fingered Portamento programmed in, your Brass patch has the right amount of Breath Control sensitivity, your split Electric Piano/Strings patch splits in the right place, and so on.

On to the rear panel as promised, and here we find stereo jack outputs (for the chorus in single mode and for the two individual sounds in split mode), sockets for a portamento and a sustain footswitch, volume pedal and tape dump to MSX-style or standard cassette player, MIDI In, Out and Thru, breath controller and headphones. There's no Tune control, but this is available as a Function Mode facility along with Transpose to put the whole keyboard into different keys.

As before it's possible to name all the sounds using the 32 memory switches as alphanumeric selectors, and now you can invent names for a whole performance setup as well. Other improvements on the LCD display include the fact that a little 'E' lights up when you edit a sound in anyway, and as before it's possible to flick back to the original value of the parameter being edited using Edit/Compare.

Also it seems that Yamaha have finally come to accept the fact that FM is pretty complicated for the beginner, and so the DX21 comes complete with two handbooks — a Playbook and an Owner's Manual. The Playbook is accompanied by a narrative cassette delivered in a heavy American accent which takes you through the book's block diagrams, flow charts and useful function guides, and there's also a section on how to create sounds (such as Brass and Glockenspiel) from scratch. Full marks for making FM a little more comprehensive, both to the uninitiated beginner and to the professional who's become a little set in the ways of analogue synthesis.

Considering the retail price of the DX21 it seems churlish to criticise it in anyway. In fact it's difficult to come up with any meaningful criticism at all, since this is virtually a no-compromise keyboard — almost anything you want can be programmed, and if it isn't available on the front panel you can get it from outside via MIDI.

Used as a keyboard expander or a sequencer peripheral the DX21 is going to be formidable, and it won't be long before we start to hear some of its 128 ROM sounds (such as the exotic Windbells and the bizarrely named Zing Plop) on chart records. Used purely as a standalone keyboard, the DX21 is pleasant to play, fast and responsive to program, and definitely professional sounding. And best of all, it looks as if there'll be none of the delays associated with earlier FM synth gear — the DX21 should be getting into the shops as you read this.

YAMAHA DX21 - RRP: £699