Could it be true? A D-50 soundalike with built-in sampled drum sounds and digital reverb? Martin Russ reviews the new Roland MT32 multi-timbral sound module.

I will be honest - when I wrote the Roland D-50 review for this magazine back in March, I confidently believed that a rack-mount version would probably be released just before Christmas or perhaps early next year. Instead, as I write, it is only August and already we have the D-550 - a keyboardless D-50 rack-mount expander. More unexpectedly, we also have another expander which looks like a very interesting item - the MT32. The first details of this MIDI sound module were released at the June NAMM show in Chicago and mentioned eight different D-50 type sounds you could play at once, 28 onboard PCM percussion sounds and a built-in digital reverb, all for less than £500...

RECENT PHENOMENON

Expanders are a recent phenomenon: until the arrival of MIDI you expected a synthesizer to have some sort of physical controller - a keyboard, guitar or wind instrument, for instance. The Yamaha TX7 was the first example I came across of a new breed of device - a musical instrument which could only make sounds when accessed via MIDI. (Not strictly true, since mine made at least one very interesting sound when I dropped it, but not many immediately afterwards!) Since the TX7, many products looking rather like car radios have appeared, including the piece de resistance of the genre - the Yamaha FB01 - which has only eight buttons and a display. "Where's the tuning knob?" being the standard question from those innocent of MIDI matters. To those who know, however, an expander is a simple and very effective way of getting the most out of a sequencer or master keyboard.

The buzz-word to look out for when buying an expander is multi-timbral. This is the ability to play several different sounds at once, usually using different MIDI channels for each sound. This enables a sequencer to play complex polyrhythmic parts and thus produce a very full and polished sound, without any recourse to a tape machine, except to record the finished piece of music in one take. Instead of using lots of individually recorded tracks to build up a song, you use lots of sounds all at once, honing each part using the sequencer, and only committing the music to tape when it is finished. The tape method needs lots of tracks and a single synthesizer, whereas the expander-based method needs lots of sounds and a simple stereo tape recorder to record the final result.

Luckily, because in an expander you can remove lots of the more expensive parts of a traditional keyboard synthesizer - the keyboard, most of the control buttons, the performance wheels, pedal sockets etc, it is usually possible to purchase an expander version of a synthesizer at a price which makes having lots of sounds available at once a viable proposition. Before expanders and multi-timbrality, you would have had to buy lots of DX7s or JX3Ps to generate several sounds at once, now you just buy an MT32!

THE PARTS

Okay - armed with the background knowledge of expanders and our carefully chosen buzz-word, let's look at the MT32.

Roland have chosen to call the separate sound sources 'Parts' and the sounds themselves 'Timbres'. There are eight Parts available, ie. you can have up to eight different Timbres sounding at once. Each Timbre is made up of one or more 'Partials' - complex sounds can use up to four Partials, whilst simple sounds may only need to use one Partial. Since there are 32 Partials available in total, the number of sounds can vary from 32 simple sounds to eight complex ones, depending upon the choice of Timbre.

How does the MT32 fit all this into its eight Parts? Easy, an intelligent note assigner uses the available Partials according to simple user-controlled criteria, including a clever Reserve function which enables you to preserve a specific number of Partials for one sound. This helps avoid the note-stealing which might otherwise appear in a Part which has to be four-note polyphonic. If you still have too many notes then you can even Overflow them into another expander via the MT32's MIDI Out...

Producing sounds on the MT32 is easy - you just connect a MIDI lead into the MIDI In socket and send some MIDI note data to it (from a sequencer or keyboard). The eight Parts are assigned to MIDI channels 2 to 9 as a default, with the PCM percussion sounds on channel 10. So, playing some notes on channel 2 we should hear some sounds from Part 1. And what sounds! - this is where it starts to get interesting, because inside the MT32 is the same Linear Arithmetic (LA) chip you will find in the Roland D-50 synthesizer, so the sounds are very similar to the individual Partials in a D-50 voice (16-bit, 32kHz sampling rate). Remember, though, that in a D-50 you always deal with 'Tones', which are made up of two Partials. In the MT32, you get the next stage below that since you can listen to single Partials if you wish, although you can still fasten Partials together into D-50 type 'Structures' if you want. [Ed - see Martin's articles in the May and June issues of SOS for more details on the D-50.]

HOW MANY NOTES?

To clarify what I have said above: depending on the complexity of the Timbres you employ, you can have eight separate Parts playing at once using just the MT32. Each Part can be just a single note for simple sounds or four-note poly for complex sounds. Thanks to the note-stealing assigner, if you only play a single Part on the MT32, you can have up to 32-note polyphony, or 8-note polyphony for the most complex Timbres that use four Partials.

When I discovered this, I began to realise why there has been so much fuss about this rather innocuous-looking black box. Most of the similarly priced competition offer only 8-note polyphony at best, whereas here we have 32 notes which can be freely assigned to any of eight Parts! Thus, the MT32 is eight Part multi-timbral, with up to 32 available notes for those eight Parts. It is like having eight polysynths!

DRUM SAMPLES

One of the most interesting aspects of Roland's D-50 is the availability of PCM (Pulse Code Modulation, ie. digital) samples of the attack portion of real sounds, as well as some more unusual combinations and looped samples. In the MT32, the PCM capabilities are exploited even more because, in addition to the 8-Part/32-note synthesis section, there is also a Rhythm Part which is used to produce velocity sensitive sampled drum sounds.

There are 28 PCM sounds in all, mapped to MIDI note numbers, and they cover the same wide range of drum and latin percussion sounds that you find in Roland's new TR626 Rhythm Composer. The MT32 seems to be able to play at least eight percussion sounds at once, although my ears seemed to be reaching the limit of their resolution when trying to decide if they could hear more than eight!

OPEN THE BOX

Your new MT32 has just arrived. Let's open the cardboard box and see what we get. Apart from the two jack-to-jack leads, a MIDI cable and a few bits of paperware, we find the above mentioned black box with a few switches and a display on the front, as well as a suitable mains power supply. As with all MIDI gear from Roland these days, you get an 'Introduction to MIDI' manual, an Owner's Manual, a copy of the MIDI Implementation with notes on the System Exclusive commands etc, and an assortment of patch sheets, sound lists, performance data, etc. 'Thorough' and 'comprehensive' are the words which spring to mind here. Roland never have had any major difficulty writing instruction manuals you can understand, and these are no exception. More than enough info to get you started, and plenty for the interested user to get his/her teeth into.

Don't attack the MT32 itself with your teeth, though! Although the sloping front panel is constructed of black matt finish plastic, the rest of the box is sturdily constructed from steel - for strength and shielding. There is a 20-character, green backlit LCD display on the left, 10 buttons on the right-hand side, and an assignable rotary control to the far right. The rear panel is similarly functional. There are the left and right audio output jacks, MIDI In, Out and Thru sockets, an AC adaptor socket and a power switch. Size-wise, the MT32 is almost exactly the same size as eight stacked copies of Sound On Sound, but much lighter! Upon powering up the device, you briefly see the ** Roland MT32 ** message followed by a display showing the master output volume and the current status of some of the sound generators inside: 1 2 3 4 5 VOL: 100.

SOUNDS

There are 128 preset ROM Timbres available on the MT32, together with RAM storage for a further 64 of your edits. The presets are grouped into 17 groups, each group containing between four and 11 Timbres. The group titles are: Piano, Organ, Keybrd, S-Brass, SynBass, Synth-1, Synth-2, Strings, Guitar, Bass, Wind-1, Wind-2, Brass, Mallet, Special, Percusn and Effects. Individual voices are best described by their titles: Orche.Hit, Fantasy, Timpani, Atmosphere, Str.Sect 1, Sax 1, Harpsi 1 and Syn Brass 1 represent a brief sample of the sort of sounds to expect. Overall a good selection of familiar D-50 type sounds, with a clever mix of complex and simple Timbres.

For maximum polyphony, you should choose only the sounds that use one Partial, and these are available for each of the major sound groups. In fact, there is usually a choice of complexity, from four Partials down to one or two: AcouPiano1 (4 Partials), AcouPiano2 (2 Partials) and AcouPiano3 (1 Partial), for example. Most of the voices are velocity sensitive, although the dynamic resolution is not as high as in the D-50 - I could only detect between four and eight different levels of velocity control. All the PCM drum sounds are velocity sensitive, too, and have about the same range of control. For most purposes, the available range should be perfectly adequate.

The drum sounds are recorded in typical Roland fashion: excellent quality and very dry. In this case, the dryness serves as a good introduction to another feature of the MT32: the built-in digital reverb.

As well as the eight synthesizer Parts and the PCM Rhythm Part, the MT32 has a high quality digital reverberation section. Although the default setting gives reverb on everything, it is possible to assign the reverb onto individual Parts. The reverb has Room, Plate and Hall options, with control over duration and intensity.

Drum sounds and synthesizer sounds can be placed in the stereo field (15 positions in all), although the default setting spreads the eight Parts over the image from left to right and places the drums in a fairly conventional arrangement with the bass drum centre, toms to the left, hi-hat just to the right, etc.

Each percussion sound is assigned to a specific fixed MIDI note number and only responds to Note On information. This means that the samples always play for their full duration (except for the hi-hats, which have the usual priority of closed over open) and so the long sampled whistle sound cannot be re-started quickly by playing the note again, for example. Note this down carefully - this is the first weak point found so far.

The MT32 is controlled either from the front panel controls or by MIDI. Apparently, the MT32 was a collaboration between Roland in Japan and the Roland R&D Centre in Europe, and was designed as an add-on for MIDI pianos to provide more sounds, but they decided that it had much more potential than that and so gave it a very comprehensive MIDI implementation. The result is that very few functions are available from the front panel, but complete control over everything is available from MIDI. (The kitchen sink controller option was not fitted to the review model...)

USER CONTROL

Using just the front panel controls, you have access to the MT32's eight synth Parts and the Rhythm Part and can alter their volume; which preset synth Timbres are used; the reverb time; the overall pitch and volume; and the System Exclusive device identification number. The LCD display shows activity on the Parts by temporarily replacing the Part number with a solid square. This means that you can only monitor activity on Parts 1 to 5, since there is only room on the display for these and the output volume readout. The pan positions are fixed, as described above, and you cannot edit any of the Timbres.

This covers all the functions of the front panel. Unlike the Yamaha TX81Z, where you can edit everything from the front panel, or the FB01, where you can edit some parameters from the front panel, the MT32 is virtually a MIDI-only device. In fact, the control you get is so limited it would almost have been more sensible to give you no controls at all and save the cost of the buttons, volume control and LCD display - but remember that the MT32 was originally designed as a home piano expander.

The front panel controls always power up in the default mode - this is the first of 128 preset memories - an additional 64 RAM memories are available for storing your own patches. Patches are only available via MIDI, and control the MIDI channels for each of the Parts; which Timbres are used for each Part; the reverb mode, intensity and time; the master tuning and fine tuning of individual Parts; master volume; panning of Parts and individual drum sounds; key shift; bender range; Partial Reserve and Assign mode. Patches are selected by sending a standard Roland-type handshake System Exclusive message, whilst patch editing uses conventional parameter change messages.

Editing of Timbres is also only possible via MIDI, although you can use Roland's D-50 or PG1000 programmer to set-up and modify most of the parameters. Roland's R&D Centre expect that a Patch and Timbre Programmer similar to the PG1000 should appear soon, but a better solution is probably to edit patches and Timbres using a computer software package. So far, software is only available for IBM PC compatibles but work is proceeding on Macintosh and Atari ST versions, I am told. At present, activity seems to be centred on providing sequenced classics for the 'home user', but the experience gained will be useful in future support to us programmers.

With all the parameters available for the Timbre and Patch editing, the programming of suitable sounds should be made much easier. I spent quite some time trying to edit some of the parameters using Fast Basic on my Atari ST, and have decided that buying an editor is probably a much easier and cheaper solution!

For real-time MIDI control, the MT32 recognises quite a few MIDI controllers apart from the rather essential Note On and Note Off type. The Modulation (MIDI controller 01H) and Volume controllers (07H) do exactly what you would expect, and so the Pan-pot (0AH) apparently wangs the output of the chosen MT32 Part across the stereo field. The Expression (0BH) and Sustain (40H) controllers are also recognised. Program Changes change the Timbre on the chosen channel and, in fact, the channelisation aspect applies to all the controllers, so you will need a good master keyboard or a comprehensive sequencer to exploit the MT32's controllers effectively. There are, of course, separate global commands for things like overall volume and tuning. Although it recognises Mode Change messages, the MT32 politely ignores them and remains in Mode 3 (Omni Off/Poly On). Thus, the MT32 follows the trend of looking like eight synthesizers rather than implementing Mono Mode.

Having mentioned the 64 Timbre memories and 64 Patch memories for the user to fill with their edited versions of sounds, it is necessary to reveal the second weakness of the MT32 - because of the large amounts of RAM needed to store all the parameters, no battery back-up is provided for the memory! So when you turn off the MT32, your Patches and mega-sounds disappear into thin air. (From a practical viewpoint, since you will be using a computer or sequencer to control the MT32, all you need do is send a System Exclusive Bulk Dump of the RAM areas when you first power-up the system, to restore your MT32 to its former glory.

CONCLUSION

A very interesting expander. I used up most of my supply of 'wonderfuls, remarkables, formidables, etc' when writing the D-50 articles, so don't expect any more here. Suffice it to say that for less than half the price of a D-50 synth or D-550 rack-mount, you get quite a bargain. The D-50's chorus and equalisation sections are absent from the MT32, but the output quality is comparable, the sound assignment is more flexible, and the PCM drums are a nice bonus. With a suitable software package, the MT32 will make a very useful expander for the sequencer user. In fact, a single MT32 plus computer-based sequencer could satisfy virtually all the requirements for a simple but complete MIDI set-up for a home recordist: synths, drums, reverb - just add vocals (and creativity) for an instant hit!

In a more professional context, the availability of software to edit the MT32 and its compatibility with existing sequencer packages will be important factors in its success, but for those of us who were saving their pocket money for a D-550, the MT32 could save a long wait! I was tempted by the D-50 - I will certainly buy an MT32!

The MT32 retails for £450 including VAT.

For further details contact: Roland (UK) Ltd, (Contact Details).