CASIO
Casiotone MT-520		   keyboard with warm timbres, drumpads & greatly versatile accompaniment

This Casio keyboard has lovely warm semi- analogue sound, sample based percussion and 8 rubber drumpads. Its special feature is the quite versatile "Super Drums" accompaniment with individually mutable tracks, and there are even individual inputs for 8 external drumpads.

The 12 semi- OBS preset sounds and chords employ Casio's classic "Consonant Vowel" synthesis engine (see Casio CT-410V), which mixes 2  multipulse squarewaves with independent volume envelopes and can make nicely warm and sonorous sounds. The 12 semi- OBS preset rhythms are made from woody knocking medium resolution samples (same percussion like with Casio CZ-230S); the rhythms consist of 4 separate tracks, those each have a slide switch for 3 variations and mute, which permits a lot of realtime variations. Also the warm sounding accompaniments have each 3 variations and intro, fill-in and ending and accept beyond establishment chords also wild disharmonic note combinations. The patterns remind to Casio CT-410V; some variations are nicely complex arranged and partly contain arpeggio. The sensitive rubber drumpads mute a running rhythm for a bar; the base drum pad even stops it entirely until a fill-in is started, which can be disturbing. Unusual is that there are even 4 stereo plug jacks to connect 8 external drumpads. There is also a primitive record/ playback sequencer (ignores drumpad sounds). The original German retail price of the Casio MT-520 was 449DM (about 225€, price tag on box).

main features:

8 drumpads can be connected.
The pcb much is smaller than with MT-500. There are unused solder holes for an additional IC.

modifications:

notes:

The case shape of this instrument resembles much the sample based Casio MT-540 and was likely one of the predecessors. The drumpad jacks could be either connected with each a Casio DP-1 dual drumpad unit or a Casio SS-1 Sound Sticks electronic drum stick. The obscure Sound Sticks were cabled drum sticks, those vibration sensor sends a signal by hitting any surface; a button on top of each stick selects between the 2 contacts in each jack to switch between both sounds. The MT-520 contains a fairly complex hardware with much analogue stuff, but the PCB is small compared with its predecessor Casio MT-500. The sound quality is similarly impressive like with Casio MT-800, although the bass of the accompaniment sounds colder. (The MT-500 has warmer accompaniment.) The CPU "HD61702A03" seems to be a close relative of the "HD61702A02" in Casio PT-100.

The preset sounds are based on filtered multipulse squarewave and thus don't sound perfectly realistic, but they have a nicely warm analogue timbre and sound quite noble. (I am not sure if only advanced filters are used or if possibly even additional waveforms are involved for some timbres, because the bass range sounds smoother, warmer and less buzzy than with most other squarewave- based Casio keyboards.) The preset sounds all apparently employs a similar  stereo chorus like with Casio CT-410V, although this one can not be controlled by the player and is always set to a slow 2Hz mode. The "piano" sounds fairly real regarding the technology. The "vibraphone" has a somewhat flute- like ethereal timbre with a dose of chorus and weak 4Hz tremolo; the bass range is fairly dull. The "jazz organ" is a Hammond organ imitation with mildly percussive attack and sounds a little squawky (but not as much as with the digital Casio SA-series keyboards), but generally quite soft and not creaky. The "violin" has a slow attack and sounds quite realistic, although high notes are a little thin. The "trumpet" sounds thin and hollow with delayed vibrato; the sonorous bass range rather resembles a bassoon or oboe. The "funky clavi." is a sort of bassy harpsichord with nicely buzzy bass range and no sustain. Also "elec. piano" resembles a harpsichord, but sounds thinner, has a fast fluttering tremolo and sustain. "elec. guitar" is similar but thinner (more sitar- like) with longer sustain. "pipe organ" is the known sonorous multipulse timbre with slow attack and short sustain that attempts to simulate a metal pipe organ rank, but this one sounds a bit too bright and thin. "human voice" rather resembles a wooden or very muffled metal pipe organ rank with short sustain; it may be a "vox humana" rank, but has very little similarity with a human voice although it sounds nicely warm. "flute" sounds like a softly blown metal flute with fluttering tremolo and mild reverb; the bass range sounds woody. "synth. sound" is a harsh and massive electronic metal pipe organ timbre with percussive attack, fast fluttering tremolo and short sustain; the timbre also resembles a harpsichord and trumpet - only high notes play too soft in relation to its loud and thin buzzing bass range. Unlike other that old Casio keyboards there is neither a sustain switch nor other sound controls. The semi- OBS preset sound buttons respond fairly fast; pressing them retriggers the notes of held keys with the selected preset sound, which can be used for live play tricks.

The percussion has a woody knocking style; the samples sound almost identical with Casio SK-8 and also the rhythms sound very similar; some of these (samba, reggae) sound quite oriental. With the "Super Drums" slider each of the 4 tracks in a rhythm can be switched to 3 variations or muted. Starting with all tracks muted, you can build up a gunk structure, which is nice for tekkno- like meditative musics. The semi- OBS preset rhythm buttons respond quite fast during rhythm and thus can be also used for live play tricks. The accompaniment has 3 switchable variations and with standard chords many patterns are similarly complex like with Casio MT-540, but unlike MT-540 this one fortunately also accepts non- chords and the fingered accompaniment changes depending on how many keys are pressed. Some variations feature arpeggios, walking bass lines and other complex ornaments. Unfortunately a running accompaniment can not be muted without disturbing the rhythm, because the "casio chord" switch always makes the rhythm stutter when moved.

There is also a simple record/ playback sequencer that records any played notes with chords/ accompaniment, but it can not be edited and records no drumpad hits.

A smaller Casio MT-520 variant with only 4 drumpads was released as Casio MT-220 and without drumpads as Casio MT-205 (both without rhythm tracks mute). The same hardware class was also used in Casio MT-110 (with neither Super Drums nor drumpads) and in the rare ROM-Pack keyboard Casio CT-805 (49 fullsize keys with key lighting, mono, neither drumpads nor Super Drums, microphone jack, case style like Casio MT-28). A fullsize version of the MT-520 was released as Casio CT-510 (with additional pedal jack (for bass drum??)). The direct predecessor of the MT-520 was the Casio MT-500, which had only 4 drumpads (each switchable to 3 sounds) but even 20 preset sounds; the MT-500 is also a nice keyboard but has other nasty flaws, thus do not believe false claims that it would be better. A smaller Super Drums keyboard with semi- analogue percussion (but no drumpads) was the Casio MT-52. Another midsize drumpad keyboard was the Casio MT-640 (based on MT-540 hardware, 6 rubber drumpads, 4 effect pads, bigger speakers | all seen on eBay).
 

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