With its 8-track sequencer, rhythm composer, digital reverb and built-in disk drive, Roland's latest multitimbral LA synthesizer would be better described as a budget 'music workstation'. Paul Ireson reveals why...

It's beginning to look as if 1988 could be the year of the workstation, the all-singing, all-dancing instrument that puts into one box the creative potential of a small studio set-up. Last month saw the Korg M1 reviewed in these pages, now it's the turn of Roland's D20 synthesizer, which - along with the D10 - is the latest recruit to the ranks of LA keyboards and expanders.

In relation to Roland's existing products, the D10 and D20 are direct descendants of the D50 synthesizer, flagship of the LA range. After the D50 came the rack-mount D550, the multitimbral MT32 and D110 modules, and now these two. The D10 and D20 are identical in all respects except for the inclusion of a sequencer and disk drive on the D20, so parts of this review not dealing with these aspects of the D20 apply to the D10 as well.

WHAT IS IT?

Internally, the D20 is certainly a lot of machine, the modest size of its case belying the extent of its hidden capabilities - it's a bit like the TARDIS really, though rest assured that the D20 is more reliable by a long shot! What you actually get crammed into the D20's case is the equivalent of eight independent LA synth modules, a 63 PCM-sound drum machine, a digital reverb, an 8-track sequencer, and a 3.5" disk drive for data storage. Phew, rock 'n' roll! Looked at another way, it's roughly a D110 with a keyboard stuck on the front, a sequencer and disk drive, and a better user interface.

It's this combination of features - multitimbral synthesis, multitrack sequencer and disk drive, drum machine and reverb - that qualifies the D20 as a true 'music workstation', a unit on which multi-part music may be composed and recorded without any extra equipment - provided you don't need vocals. All-singing, no, but all-dancing, maybe.

A good way of hearing just what the D20 is capable of is provided by the ROM Play facility. Eight short pieces of music, ranging from arrangements of classical music to more up-to-date originals, are burned into ROM somewhere in the depths of its circuitry. Call one up, press Start, and you will be impressed. I can see demonstrators in music shops using this feature a lot over the next few months, and I imagine it will sell a good many keyboards for Roland.

Speaking of which, the D20's keyboard is of the 61-key touch sensitive variety, and to its left is a Roland style pitch bender/modulation lever. Behind this sits the 3.5" disk drive, which slopes into the front panel of the instrument creating a tray suitable for housing Maltesers, paper clips, or even the odd floppy. In the way of front panel controls, the D20 gives you Volume and Data Entry sliders, a 32-character backlit LCD display, and 38 assorted buttons for accessing the D20's functions; operating the sequencer, editing sounds etc. The eight Bank and Number buttons for Patch and Timbre selection double as Track selection and Mute buttons in sequencer mode.

The rear panel incorporates headphones and left and right audio output sockets (all jacks). The blow of finding no individual outs was softened by the discovery that pan positions can be assigned for each percussion sound independently, and may be continuously changed and recorded for synth sounds when using the sequencer. Three DIN sockets take care of MIDI In, Out and Thru, and there are three more ¼" jack sockets for Hold, Sequencer Start/Stop and Punch In/Out footswitches. A memory card slot is also provided.

Extras included with the synthesizer itself are a two volume owner's manual (clear and comprehensive, and it even looks good), quick operation charts, a blank disk, and a sound chart listing the memory locations of the factory preset sounds.

THE SYNTHESIZER

The synthesizer section of the D20 uses Roland's familiar LA (Linear Arithmetic) synthesis technique, and operates in one of two modes, Performance or Multitimbral. The former configures the D20 as a 'conventional' synthesizer, with the instrument's own keyboard controlling all the available sound. The latter, as its name implies, allows several sounds to be produced simultaneously, for use with the sequencer or control by external MIDI instruments. Before describing what sounds are available in the two modes, a brief recap on LA synthesis is necessary. For a more detailed description, see the D50 (May/June 87) or MT32 (Sept 87) reviews in previous issues.

The basic unit of sound in LA synthesis is a Partial, the Partial being to LA what the Operator is to FM. Each Partial may be a synthesizer waveform (square or sawtooth) or sampled PCM sound. The 256 PCM samples available on the D20 cover a range of 'one-shot' sounds, percussion voices or attack portions of acoustic sounds, and looped sustain portions of the same or similar types of sound. Take from one to four Partials, apply filter and amplifier envelopes to synth waveforms, amplifier envelopes only to PCM waveforms, arrange in a Structure, and you have a sound which Roland call a Tone. On the D20, 128 preset Tones are arranged in two groups of 64, and a further 64 user programmable Tones are available. A memory card will give you space for another 64.

The sounds that are played by the synthesizer, in either Performance or Multitimbral mode, are not Tones but souped-up versions of Tones called Patches and Timbres, which add reverb and performance data to the basic sounds. In Performance mode, any one of 128 Patches may be accessed, each Patch being an arrangement of one or two Tones across the keyboard. If two Tones are employed, they may either be split or layered. Besides the choice of Tone(s) and Patch name, the parameters making up each Patch are: Patch Level, Tone Balance (Upper/Lower), Reverb Level, Type, Time and On/Off (Upper/Lower), Key Assign Mode, Bender Range (Upper/Lower), Fine Tune (Upper/Lower), Key Shift (Transpose), Split Point and Key Mode (Whole/Dual/Split).

Multitimbral mode is where the fun really begins, as it configures the D20 as an eight-part multitimbral synthesizer - eight polyphonic synths in effect. To each part is assigned a Timbre (equivalent to a Patch in Performance mode) and a MIDI channel. The keyboard is split into two zones, Upper and Lower, each of which has a MIDI channel assigned to it, meaning each synth part may be played either from the keyboard, by an internal sequencer track, or by an external MIDI device (another sequencer perhaps). The Timbres that are assigned to each part employ only a single Tone. Key Shift, Fine Tune, Bender Range, Assign Mode and Reverb On/Off parameters are also set. Two groups of 64 Timbres are available, this capacity doubling if a memory card is in use. Reverb type and level are set globally, not for individual parts or Timbres, but you can at least turn the reverb on or off for each part.

Voice allocation between the eight parts is dynamic, and the D20's polyphony is not fixed, being limited by the availability of Partials. Up to 32 Partials may be employed simultaneously, and as Tones use from one to four Partials, it is the number of Partials per Tone (and, therefore, per Timbre) that determines how many notes may sound at once. Maximum polyphony is 32 notes if all the Timbres in use require only a single Partial each; if each Timbre uses four Partials, then only 8-note polyphony is available. Unfortunately, there seems to be no way of reserving Partials for important parts, to prevent selected sounds being cut short in mid-decay, though mention of Partial reserve is made in the D20's MIDI implementation. Strange.

Unlike the MT32, editing sounds on the D20 - whether it be Patches, Timbres or Tones - is both possible and fairly painless. Although no D50-style joystick is provided, there are enough buttons to allow Partial Select and Mute at a single push, and all other parameters may be accessed in a couple of steps. Being an LA synthesizer, the range of sounds both provided and possible is similar to the MT32 and D110, so I refer you to reviews of those products for details. Suffice to say that the LA sound does seem to be flavour of the month, and the D20 has a lot of it. Subjectively, it sounds a little bit noisy, but without conducting a side-by-side comparison with other LA units, or rival keyboards like the Korg M1, it would be unfair to say more than that.

RHYTHM SECTION

The D20's 63 PCM drum and percussion sounds are uniformly excellent: 'tight', 'punchy' and 'dynamic' are words that spring to mind, along with 'lots', 'versatile' and 'wow'. 32 preset rhythm patterns are provided, and there's memory space for a further 32 user patterns. In manual play mode, or when programming rhythms, the 63 sounds are assigned one to each of the notes on the D20's keyboard. The quick-witted amongst you will be wondering how 63 sounds fit on to 61 keys, and of course, they don't. The two drum sounds left over are assigned to the two notes (B1 and C#7) that would be adjacent to the D20's existing keys, and may be reached either by transposing the keyboard or assigning the sounds to different keys by editing the Rhythm Setup.

The Rhythm Setup is the D20's internal map of how its percussion sounds are assigned to up to 85 MIDI note numbers. As 63 PCM percussion sounds are supplied, the 'spare' 22 notes may be used for playing LA synth voices from the rhythm section, by simply assigning whatever Tones you require to a note number when editing the Rhythm Setup. So, if you feel that 63 drum and percussion sounds aren't enough, you can create your own and use those as well.

Rhythm section sounds can be played by an external MIDI controller; I tried this feature with Roland's Pad 80, which proved to be a great boon in programming patterns. There's something about being able to hit a pad and hear drums that makes a huge difference in writing drum parts, the process becoming easier and producing more exciting rhythms - playing the sounds from a keyboard just isn't the same. The velocity sensing recognises 128 levels of dynamics, as on the synth section. Patterns may employ five levels of quantisation (six if you count 'Off'), set during recording only. Changing quantisation level whilst recording is possible, allowing different instruments to be programmed at different resolutions, and a conventional drum machine-type erase function is provided, enabling specific notes or whole instruments to be cleared. The range of time signatures is limited - from 1/4 to 8/4, and up to eight percussion voices may sound simultaneously. No rhythm pattern can use more than 96 notes, and when patterns are chained together to form a rhythm track, 500 bars is the limit. There's also a handy metronome to help you keep in time when recording drum patterns.

8-TRACK SEQUENCER

The onboard sequencer is probably the D20's main selling point-it is, after all, the only feature not found on the D10, so if you're thinking of spending the extra £400 or so, it must be for this reason. The sequencer is very much a tape recorder style device; one rhythm and eight music tracks with real-time note entry only, punch in/out, and the ability to re-record from any bar. Punch in/out is instigated either by footswitch or via the front panel Enter button.

The rhythm track is composed of chained rhythm patterns, as described above, and it is from the rhythm track that the sequencer obtains its bar count. The eighth track may be employed either as a music track, like tracks 1-7, or as a rhythm track for recording additional fills and variations on top of the principal rhythm track. Unfortunately, like tracks 1-7, it can only accept note input from the D20 keyboard when recording, so playing all those fills with any drum-to-MIDI device is out. Shame.

Recording is a doddle; in count-in mode, you have two bars of metronome beeps to play along to, plus whatever music is programmed into those two bars, before recording starts at your chosen point. Any notes played before this point are ignored. There's no need to specify how long you want to record for, the sequencer just records whatever you play until you press Stop or the 500 bar limit of the rhythm track is reached. Key-on recording differs in that recording starts from the set point as soon as you play the keyboard. Until then, the metronome beeps at the programmed tempo so that you come in on time. The visual feedback given by the sequencer is good - the eight multi-colour LEDs built into the numeric buttons double as track status indicators; green indicating a track that has been recorded on, red a track currently selected for recording, and orange a track selected for an overdub. No light indicates that the track is either empty, or muted.

The Overdub facility does just what it says, allowing note or performance data to be dubbed on top of an existing track. The process is not irreversible, as you are given a chance to review the combination of overdubbed and original data before deciding whether or not to merge the two. Program Change, Pan and Volume information may all be dubbed on to a track, as well as the more obvious Note and Pitch Bend data. Besides being enormous fun, this facility allows a fair degree of re-mixing of tracks. 15 pan-pot positions are available, and although notes cannot be panned in mid-voice, the ability to change pan position for every note of a track should satisfy most people. Tracks may be erased, or have only Program Change or Pan/Volume info cleared in preparation for overdubbing as above.

Each of the eight sequencer tracks can play either an internal part (from the synth) or an external MIDI device. The latter option is chosen by muting that track in sequencer playback mode. Songs may be up to 500 bars in length and contain up to 16,000 notes.

Five levels of quantisation are available, but the quantising procedure is less flexible in track recording than in rhythm pattern recording. Quantisation must be applied to whole tracks, so even if it's just one bar that needs tidying up, every other note on that track gets quantised along with it. An unfortunate limitation.

Another gripe is the absence of any copy or repeat function. Call me lazy, but if I want a four-bar riff to repeat 16 times, I'd rather play it once and copy it over and over than play it into a sequencer 16 times. Things could be even worse if the four bars in question are the kind of part that I can play correctly only one time in ten. There's also no way of moving tracks or parts of tracks around, so if you want to do any drastic re-arranging it means playing everything all over again. In order to get the best out of the D20's sequencer and avoid such problems, it may be wise to plan ahead before starting to record.

The other side of all this is that it makes the sequencer very easy to understand and operate, and you can get results very fast, but I'd happily trade a little of this simplicity for some more editing functions. Nevertheless, despite its omissions the sequencer is more than a mere musical notepad, and is quite capable of producing complex, multi part compositions.

DISK DRIVE

OK, I lied: the sequencer is not the only D20 feature missing from the D10. The 3.5' disk drive allows song, sound and rhythm data to be saved on media a good deal cheaper than memory cards. This is not to say that the disk drive makes memory cards redundant: whereas a memory card doubles the internal memory available for sound and rhythm storage, the disk drive allows dumping and retrieval of all or parts of that internal memory. The sequencer memory is not battery backed, so song data must be saved on disk, though sound and rhythm data do survive powering down.

Disk capacity is about 35,000 notes, so a single disk will hold two memory-busting songs - more if your compositions are shorter or less complex. Loading time for a full set of sound data is about 20 seconds, and a full memory dump (of a busy, three-minute composition) took 40 seconds to load back up. Disks must be formatted before use, a fact that caused me a few moments of anxiety when it came time to save my first D20 composition. In my eagerness to play with the sequencer, I didn't even think about formatting any disks. Would the process of formatting a disk erase the valuable contents of the sequencer's memory? Fortunately for me, the Roland designers obviously realised that this would cause untold grief to users, and having spent an anxious 2½ minutes waiting for the blank disk to format, I found the sequencer memory just as I left it.

Files may be given names up to 10 characters long, and are automatically labelled according to whether they are All (whole memory dump), Song, Sound or Rhythm files.

REVERB

The D20's built-in digital reverb provides eight preset effects: small and medium rooms, medium and large halls, plate, and three delay settings. Decay time may be set from 1-8, and effect level from 0-7. As on the MT32 (though strangely not the D110), reverb may be switched on or off for each part individually in Multitimbral mode. This ability, along with the quality of the effects, makes the reverb very much the icing on the workstation cake, implementing the one essential studio effect in a very usable way.

VERDICT

The realisation of the workstation concept on a relatively budget level instrument is an interesting development, one which goes very much against the trend towards MIDI-induced modularity seen over the last few years. I refer to 'budget level' because systems such as the Fairlight, Synclavier and Emulator III are obviously music workstations, but are hardly within the reach of the average musician. The new breed, however, are.

As I said at the start, the D20 is a lot of machine, a powerful and easy to use music production centre in its own right. 'Synthesizer' really is too small a word for it, though the fact that everyone calls it a synthesizer reflects just how much our expectations of what one keyboard can do have risen. To be fair, Roland actually describe the D20 as a 'Multitimbral Linear Synthesizer, Multitrack Sequencer'. I'd call it a workstation myself, and save breath.

Overall, I was very impressed by the D20, both by its sounds and ease of use. Limited though the onboard sequencer is, it's much more than just a musical notepad, and the convenience of bringing everything together in one unit is not to be underestimated. The presence of a disk drive is very welcome, and given that many people would consider it essential for a sequencer, it's odd that the Korg M1, rightly or otherwise considered a direct rival to the D20, doesn't include one.

A couple of years ago I would probably have killed for something like the D20. I may be mellowing a little, but I think I could still bounce a cheque for one!

Price £1245 inc VAT.

Contact Roland (UK) Ltd, (Contact Details).