Casio MT-52

keyboard with versatile semi- analogue rhythm & accompaniment

This keyboard has semi- analogue sound and semi- analogue percussion with versatile "Super Drums" rhythm slide switches and accompaniment. The coarse multipulse squarewave timbres sound nicely cheesy.

The general behaviour of this instrument has many similarities with Casio MT-500, but the percussion is semi- analogue instead of sample based and it also lacks the drumpads and drum trigger inputs. Also the timbres have a coarser multipulse squarewave- appeal that sounds less noble but nicely cheesy. The original German retail price of the MT-52 in a German Conrad catalogue from 1988 was 299DM (about 150€). Also a white version was made.

Due to the many similarities I only describe here the differences to the Casio MT-500.

different main features:

44 midsize keys
mono (only 1 built- in speaker with unpleasant loud midrange resonance)
no drumpads
12 semi- OBS preset sounds {piano 1, harpsichord 1, elec. guitar, jazz organ, flute, trumpet | piano 2, harpsichord 2, celesta, pipe organ, violin, synth. reed} (selected through 6 locking OBS buttons + bank switch button)
8 semi- OBS preset rhythms {rock, 16 beat, bossa nova, slow rock | disco, swing, beguine, waltz} (selected through a slide switch + bank switch button)
4 "Super Drums" rhythm variation slide switches {base drum, snare drum, conga, cymbal/ high hat} (each 3 variations, no mute)
3 accompaniment variations slide switch
2 rhythm variations slide switch
sustain switch
main voice sound generator like Casio CT-410V (without synth filter)
semi- analogue percussion (same type like with Casio CT-410V); the cymbal timbre sounds half- way metallic.
multi-chip hardware:

accompaniment CPU= "NEC D930G 020, 8516XK, Japan" (80 pin SMD)
main voice soundchip= "NEC D931C 011, 8514KY, Japan" (42 pin DIL, same like Casio CT-410V)
IC "2063, 6500(?)" (16 pin SMD)
IC "BA4558, 505 956" (8 pin DIL)

tuning trimmer
only jacks for AC-adapter and line out

modifications:

polarity protection diode added, power supply jack polarity corrected.

notes:

The speaker of this thing sounds quite thin and has the same unpleasant midrange resonance like Casio PT-30. But unlike the latter, the PCB here is well accessible and a clear straight forward design like made for circuit bending. E.g. the 4 discrete analogue percussion envelope circuits form a well visible rectangular section and have each a trimmer for adjustment. (I haven't analyzed the hardware further yet.)

The main voice of the MT-52 sounds coarser and more squarewave- like than with Casio MT-500; it seems to be based on the same sound engine like Casio CT-410V (without its synth filter). As usual with squarewave- based instruments, the timbres have a characteristic buzzy bass range. "piano 1" is a usual filtered squarewave piano, while "2" is brighter with short sustain. "harpsichord 1" is bright and thin (like expected) while "2" sounds duller with knocking attack and rather resembles a harp. "elec. guitar" sounds bright with mild attack and delayed vibrato. "jazz organ" is a dull Hammond organ timbre. "flute" sounds like a metal flute with delayed vibrato. "trumpet" sounds a little oboe- like with delayed vibrato. "celesta" has a semi- metallic timbre with percussive attack. "pipe organ" attempts to be a metal pipe organ rank, using a sonorous multipulse squarewave timbre, but this one sounds thin and by its high octave setting no really low notes can be played. "violin" sounds ok with delayed vibrato. "synth. reed" is a muffled envelopeless plain squarewave timbre with weak delayed vibrato. All vibratos have 6Hz. Depending on the selected preset sound, the sustain switch adds sustain or reverb to the sound, but sounds those already contain internal sustain ("piano 2", "celesta") simply ignore it.

Also the percussion sounds much like with Casio CT-410V. Despite only 8 preset rhythms there are plenty of variations adjustable because each has 2 rhythm variations and like with MT-500 there are 4 Super Drums switches those switch 4 percussion tracks among 3 variations each. Annoying is that also here the individual percussion tracks can not be muted individually. The patterns differ from MT-500 but the accompaniment also here accepts non- standard chords, and they are even programmed more versatile; e.g. "slow rock" contains an arpeggio that plays the more notes the more keys are held down in the accompaniment section. Also the fill-in pattern has accompaniment. The bass and chord voices employ nicely sonorous multipulse squarewave, that is less muffled here than with the MT-500.

An MT-52 version with 49 fullsize keys was released as Casio CT-320 (released in a brown and a gold metallic case variant).

*removal of these screws voids warranty...*

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