Letron MC-3 digital squarewave keyboard with C64 sounds, accompaniment & programmable rhythm

This very common instrument is likely one of the last non- toy squarewave keyboards; it was regularly sold at least until 1995, and it is a "must to have" for every real squarewave lover because it is not rare and thus easy to find, has a relatively large keyboard, 4 note polyphony and accompaniment in the unique combination with the famous sounds of a Commodore C64 home computer or classic Gameboy. (Unfortunately none of the really freaky or more advanced C64/ SID sounds are built-in.). It has even a programmable(!) simple drum computer ("custom drummer", only 1 pattern) with 5 drumpad buttons and very electronic sounding special blip percussion. The accompaniment can play nicely disharmonic because it accepts any note combinations and not only those few those establishment defined to be "chords".

Interesting is also that this thing has less polyphony than the also squarewave based Yamaha PS-2, despite the latter came out about 15 years earlier. Many other case variants of this keyboard were released under a great variety of different brand names (see below). These often have "MC-3" in their model name, but my specimen has no "MC-3" label, because it was likely the first model of the Letron brand. But I think that "Letron MC-3" is the genuine full name of this instrument, because later(?) specimen (seen on eBay) were indeed labelled this way, and at least one other Letron keyboard type was released with a different "MC" number. Beside MC-3 also other squarewave keyboards exist with the same sound hardware and partly even more interesting accompaniment styles, but unfortunately many of these are quite rare and thus difficult to find.

(Note: This keyboard sounds great, but don't buy one of these so far your only intention is to get a keyboard with faithfully imitated natural instrument sounds. Remember, this is a squarewave instrument and thus many of its sounds sound not even remotely like what is written on its buttons, though bought with wrong expectation it may disappoint you.)

main features:

There is no model name on this keyboard.




All preset sounds are made from unfiltered squarewave with different pulse widths and a simple volume envelope (ADSR?). They contain neither own vibrato nor tremolo and most of them sound not remotely like what their name suggests. But interesting for playing is that the 12 OBS preset sound buttons, "vibrato" and "sustain" can also be pressed while keys are held down without stopping their notes. By rhythmically pressing these buttons, this way many arpeggiator- like timbre changes can be created, thus this button field can be regarded as a realtime sound control, and unlike with many other digital instruments, the button field even responds almost immediately without delay.

The automatic accompaniment responds a little slowly, thus chord changes happen 1 rhythm step delayed in the exact sync of the rhythm; possibly this shall help beginners to sound more precise, but it also confuses and limits the expressivity. When in fingered mode with no rhythm (i.e. organ chords) multiple keys of a chord are pressed, the chord continues sounding until all of these keys have been released or a different chord is played; this prevents strummed/ chinked chords and other more advanced play tricks. 7th chords can't be played anyway due to the limited polyphony. (But remember, a C64 computer also had only 3 voice polyphony, and its low voice count event formed the particularly clearly structured music styles of it a lot, though this is not necessarily bad.) Great is that the automatic accompaniment also works well with any key combinations and does not force you only to play those few ones that establishment has defined to be "chords". The accompaniment simply plays the more simultaneous notes the more keys are pressed, which permits also great cacophonic patterns. (This is in no way a matter of course - see e.g. Yamaha PSS-390 for a bad example.)

The static voice assignment of the instrument is a little annoying, because in any chord modes only 1 voice remains for the user selected sound in the right keyboard section, no matter how many voices are really actually occupied with chords or other accompaniments. In manual bass mode even only 1 voice for the left (manual bass) and 1 for the right keyboard section remain; the 2 other voices don't get used at all.

With the "custom drummer" feature you can program your own rhythm pattern by first selecting a preset rhythm as a template of the desired step count and then pressing "program" and entering step by step a sequence of drumpad presses and pauses (="play/ space" button) until the lit "program" LED unlights. You can also enter polyphonic sounds, although it needs some training to press multiple drumpads fast enough together, because as soon there are any barely audible pauses in between, they will be recorded as multiple steps. (Programming can even be done while playing on the keyboard and even with rhythm and/ or accompaniment on, but it is not a realtime programming but takes as long as it needs to enter enough steps for the pattern (up to 16), which makes this rather contra- intuitive for live play.) Then press "play/ space" to start the programmed custom rhythm pattern, which will play with the accompaniment of the previous preset rhythm when accompaniment is enabled. The accompaniment for the custom pattern can be changed by selecting a different preset rhythm and (re-)starting the custom pattern by pressing "play/ space". An interesting pug (or easteregg?) is that you can select this way different(!) pattern lengths for rhythm and accompaniment, which makes run both out of sync like a poly- rhythm and creates an interesting sound texture (i.e. accompaniment and rhythm pattern both step with the same speed but restart independently by the different step counts of both patterns).

The separate soundchip "DSG-MC-3 2191" might also be interesting for circuit- bending, due to its data lines could be theoretically interrupted, swapped, interconnected etc. to mess up sounds and accompaniments in weird ways, much like I did with the FM soundchip of my Fujitone 6A. During measurement in the Letron I accidentally shorted some stuff, which changed the rhythm styles etc. without locking up the program.) I don't know if the manufacturer once planned to exchange one of both ICs with a more advanced version or something similar; by the rather low complexity of CPU and soundchip it makes otherwise technically not much sense to separate their functionality into 2 ICs. Possibly the CPU ("MC-3DX 153014") might even be wireable with 2 DSGs to double the polyphony in more expensive versions of this instrument. If anybody finds such a version, please let me know how the ICs are wired. I later bought a Thompsonic TS-33 keyboard (MC-33 hardware class), which CPU indeed controls 2 DSGs to achieve 8 note polyphony. Interesting is that the DSG seems to be identical with a Yamaha YM2163 soundchip that I found in the Testron CL-60910 and several other similar keyboards. I am not sure if the DSG employs internal envelope capacitors, because although it doesn't sound really analogue, I discovered an odd behaviour with my Penrod AJ-430, which has an identical sounding sound generator integrated into its CPU and made odd envelope glitches at too high supply voltage, which hints to the existence of such internal caps those behave leaky at too high voltage.

Keyboards with this hardware exist in a variety of different cases and were sold under many brand and model names. They can be recognized best by their "500 Miles Away From Home" demo tune (only 1 demo, which cycles through all instrument sounds). Other characteristic elements are 5 drum pad buttons, a "A. B. C. volume" pot, 12 sound + 8 rhythm buttons and a "custom drummer" section with a "program" and a "play/ space - cha cha" key and perhaps the "manual bass" button in the "auto bass chord" section. These keyboards often have "MC-3" in their name. I assume that the electronics was originally designed by the Chinese manufacturer Medeli.

My Letron instrument has a black, rectangular case with the speakers left and right above the keyboard. Between them are many grey, and fewer blue, orange and green buttons and left next to them are vertical sliders for power and volume controls. The most remarkable element are many rectangular red LEDs near the button fields and at the top a row of 5 small and green, hexagonal drum pad buttons (those tend to get stuck under the case rim). The case design has some similarities to my Hing Hon EK-001 and may be partly imitated or modelled after mid 1980th Yamaha keyboards. Especially it has many style elements common with Yamaha PSS-460, PSS-470, PSS-570 (e.g. slide switch shapes, the grooved back edge and the many red rectangular LEDs) and also PSS-260, although it is no direct imitation of these.

Many other keyboards of this "MC-3" hardware class exist with a variety of different names. By watching eBay, I yet identified at least 5 different case designs. (The button colours may vary.) These are some pictures and model names I found on the internet:


same case:
Bestar MC 3
Condor MC-03
Diamant Sound MC-3
Elite MC-3
Eurotone 3B* (??)
Fujitone 3
Gran Prix GPX KB898
Intersound MT-3000
Letron Stereo MC-3
Medeli MC-3
Medeli MC-3 DX

*) I am not sure about Eurotone 3B; someone described it at the phone ("5 green drumpads" etc.) but I neither saw nor heard it.

Fujitone M/3A
(note the bigger drumpads and less LEDs)

same case:
Angeltone DM-280
Fujitone 3A
Fujitone 3-A*
HBA International (= "HBA Tec" ?)
Medeli MC-3 DX (2nd version)

*) contains no MC-3 hardware.

Fujitone IIIB

same case:
Bahman IIIB
Baytec MC-3A
Fujiyama 3A (version 1)
Hamisonic MC-3A
HBATEC (no type name on case)
Kansai 3K
ME-YA 1701
Monacor MC-3A
Musikland MC-3A
Nagasaki 3A
Sigmatone SG 300 (or SC-300?)
Thompsonic TS-03
Tristar MC-3A

Transtec 898

same case:
Kamosonic F3A
Mayatone MC-3B

GPM MC-5000*

same case:
PanToys MC-5000*
Elite MC 3000
Tristar MC 3000

*) contains no MC-3 hardware.


same case:
Fujiyama 3A (version 2, yellow drumpads)
Fujiyama 5A (same like that Fujiyama 3A)
Kawasaki 5A (yellow drumpads)

But it is not sure that keyboards those look like these contain always MC-3 hardware. I also own the HBATEC and the Fujitone 3-A, those both look almost exactly like my Letron, but contains a very bizarre sounding analogue squarewave hardware which may be a predecessor. But these hardware variants seem to be extremely rare, thus instruments those look like an MC-3 usually are one. An MC-3 successor with same control panel layout but FM sound was released as MC-5000. MC-3 keyboards are quite easy and inexpensive to find at eBay. (Variants without MC-3 hardware can be distinguished mainly by their OBS sound button names.)

A direct successor of the Letron MC-3 was the Letron MC-38 and a more advanced and programmable one the Thompsonic TS-33. A technically simplified MC-3 variant was released as Penrod AJ-430 (no separate sound chip, only 2 volume sliders, great accompaniment, 2 demos).

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