Casio MT-30 Polyphonic Synthesiser
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Casio really stirred up the synthesiser industry by releasing the CT-201 and M-10 polyphonic synthesisers just over a year ago. At a price that would previously have only bought a cheap monophonic synthesiser, the CT-201 rapidly established itself as a favourite amongst bands needing a bright, digitally-clean keyboard. What isn't widely known is that both these keyboards used the same VLSI chip, the D773G, and the main difference in circuitry lay in the addition of a programming switch in the more expensive model. A certain amount of criticism was made of the limited keyboard length and small number of presets (4) in the M-10, but, for about £80, this still represented excellent value for money. Whilst Casio have upgraded the CT-201 to the CT-202, they've also replaced the M-10 with the MT-30, and I'm very impressed with what it offers for an average retail price of about £90.
As with the M-10 and CT-201, all sound generation is performed digitally by a 64-pin VLSI chip, but this time it's a D775G, presumably an updated version of the D773G. Each of the 22 instrumental sounds have a note range of 3 octaves, but the starting point varies with the different instruments as follows:
C1-C4: Electric piano, Brass, 'Cello, Synth-Fuzz.
C2-C5: Banjo, Guitar, Harpsichord, Organ, Accordion, Pipe Organ, Violin, Trumpet, Strings, Clarinet.
C3-C6: Xylophone, Celesta, Glockenspiel, Oriental Pipe, Fuzz, Flute, Recorder, Folk flute.
The block diagram in Figure 1 outlines the basic format of the MT-30 circuitry. The keyboard and programme control switches are encoded into the 775 by way of a scanned matrix. This matrix operates in two modes: 'play' and 'set'. The 'play' mode generates up to eight voices as a function of the depressed keys. In the 'set' mode, the last white key depressed determines the instrument sound to be loaded into the tone memory. Four sounds can be loaded at once into the tone memory and are recalled and reproduced at leisure by sliding the selector switch to the required number. The output of the 775 is straight binary, which is converted to analogue by the D to A, filtered, and sent to a power amp and the internal speaker, or to a line output phono socket.
Certain adaptations have to be made to one's playing technique, if not one's anatomy, when using the MT-30. This is basically due to the fact that the inter-octave spacing on the MT-30 is only 5½", in contrast to 6½" on the standard, i.e., non-Japanese, keyboard. I'd normally count myself as being fairly dexterous, but even my ectomorphic fingers found themselves getting wedged into tight corners when playing certain chords with mixtures of white and black notes; the biggest offenders were tetrads of E-flat or B-flat major in the left hand, which necessitated the use of inversions or some very curious changes to pianistic technique to get over such barriers to spontaneous creativity. A plus point of this reduced spacing is that Bach and other contrapuntal extravaganzas immediately become much easier - no more straining to play that tricky tenth chord.
The presets offer a good variety of sounds, but you have every right to expect that from a keyboard offering 22 instrument definitions. What you don't get, though, is 22 different instruments, as many of the instruments in each octave group tend to sound rather similar. So, don't be surprised if you don't hear any difference between xylophone, celesta and glockenspiel, or organ, accordion and pipe organ! What you do get is some sounds which really are rather good - favourites of mine are the recorder preset, which has a superb breathy quality that's really silky, and the synth-fuzz preset, which gives a good rock sound. Examples of these and others can be heard on the 4th E&MM demonstration cassette.
Two other controls allow a certain amount of sustain to be introduced and the addition of vibrato. With some instruments, the sustain isn't enough (notably strings), and, with others, it's too much, which just goes to show that all or nothing switches aren't a good thing. The same criticism could be applied to the vibrato function, but it is at least a pleasant extra and does add warmth and animation to otherwise static sounds.
A more serious gripe is that, like the M-10 and CT-201 predecessors, the MT-30 has no pitch control. This is a really strange omission when you consider that even the VL-Tone has one, but I'm pleased to report that the MT-30 was spot-on with A-440. To be fair to Casio, it should be pointed out that the MT-30 was never intended as anything other than a 'leisure instrument', and therefore a pitch control wasn't deemed necessary. For the supply of power, the MT-30 uses either 5 x HP2-type batteries (which it consumes with greed) or the inevitable AC adapter.
The quality of sound from the internal loudspeaker is adequate, in the sense that it doesn't rattle or squeak, but line connection to an external amp can be made, either by a phono socket, which annoyingly doesn't disconnect the internal speaker, or by a headphone socket, which produces a low impedance, high level signal that tended to distort with my mixer.
The deviant keyboard on the MT-30 won't win it much favour with pudgy-fingered players, but, as a 'carry anywhere' source of some very acceptable polyphonic sounds, there's no reason why it shouldn't find a lot of popularity in small studios, bedrooms, bathrooms, or anywhere else that might inspire you to grab a fistful of small but tasty notes in the middle of the night!
Review by David Ellis
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