small digital synth keyboard with effect processor & sing input

This very interesting Casio keyboard from 1992..1993 (embossed case date) has a built-in digital effect processor with microphone input, which can produce many kinds of reverberations, pitch shifting, vibrato/ tremolo, chorus, flanger (sounds like mellow tape mess, but is great for celestial sound pads) and some very weird howling feedback/ LFO sounds those resemble much to 1950th horror or psycho thriller movie effects.

Generally this keyboard's sound quality is partly very lo-fi and at the edge between toy and real instrument, thus it is likely no replacement for a modern studio effect processor. (The initial retail price had been about 199€, which later dropped to 49€.) But due to the effects can drastically modify the 100 fixed preset keyboard sounds and each effect can even be adjusted by up to 2 parameters (e.g. intensity and frequency) using drumpad buttons, the DSP feature should be mainly understood rather as a versatile digital synthesizer function than a serious effect processor. This hardware was one of a kind that AFAIK was never reused in any other Casio keyboards.

main features:

• 32 midsize keys
• 2 built-in speakers (hissy and bassless)
• stereo (effects stereophonize the initially mono keyboard and microphone sounds)
• polyphony 6 notes
• 100 preset sounds {piano, elec piano 1, honky-tonk, harpsichord, toy piano, jazz organ 1, street organ, pipe organ, church organ, elec organ, brass 1, horn, trumpet 1, warm brass, tuba, fat brass, oboe, saxophone, bagpipe, clarinet, flute, whistle, ocarina, recorder, harmonica, pop-lead 1..2, synth-lead 1..3, strings 1, ensemble 1, violin, viola, cello, harp, pizzicato 1, shamisen , pizzicato 2, mute guitar 1, wood bass, elec bass, synth-bass, gut guitar, dist guitar 1, acous guitar, elec guitar, jazz guitar, mute guitar 2, dist guitar 2, jazz organ 2, e. clavier, accordion, elec piano 2, power-lead, brass 2..3, trumpet 2, strings 2, pulse vocoder, choir 1..2, wav voice, choir 3, glass harmonica, cathedral, banjo, church bells, twinkle echo, synth-guitar, airplane, cosmic dance, insect, emergency alarm, laser beam, pearl drop, telephone, car horn, computer sound, sample percussion, marimba, xylophone, afro percussion, bells, gamelan, vibraphone, steel drum, music box, rock drum, disco drum, bass/ guitar, bass/ trumpet, bass/ piano, bass/ lead, piano-strings, marimba-strings, flute-vib, wind ensemble, choir 4, ensemble 2}
• 12 preset rhythms {rock, disco, swing 2 beat, swing 4 beat, samba, bossa nova, beguine, tango, march, slow rock, waltz} (without chords)
• 59 built-in preset effect combinations (each consist of 1 or 2 combined basic effects) {small hall, large hall, stadium, disco, metallic room, delay, stereo delay, pitch shifter, dual pitch, ensemble, flanger A..B, chorus, distortion, tremolo, vibrato, heavy vibrato, panning A..B, vocoder, distortion/ flanger, distortion/ stadium, chorus/ delay, chorus/ small hall, flanger/ delay, flanger/ small hall, small hall/ vibrato, vibrato/ small hall, vibrato/ chorus, vibrato/ tremolo, ensemble/ small hall, ensemble/ delay, ensemble/ flanger, dual pitch/ small hall, dual pitch/ delay, tremolo/ small hall, tremolo/ flanger, delay/ flanger, large hall/ panning, stereo delay/ small hall, heavy vibrato/ stereo delay, heavy vibrato/ chorus, random vibrato/ small hall, pitch shifter/ small hall, pitch shifter/ chorus, pitch shifter/ feedback, distortion/ small hall, distortion/ delay, transpose/ chorus, transpose/ small hall, ensemble/ panning, dual pitch/ panning, heavy vibrato/ panning, tremolo/ panning, small hall/ panning, distortion/ panning, vocoder/ small hall, vocoder/ stereo delay, vocoder/ flanger, non effect}
• 9 effect memory user presets
• pseudo- vocoder (envelope follower)
• "pitch sensor" sing- to- note converter which shall permit to play keyboard notes by singing, but it is almost unusable because it works only reliable within about 1 octave and otherwise randomly jumps to wrong octaves.
• 5 drum pads, switchable by 3 buttons to play 2 drum kit (A=normal, B= synth toms/sirens) or as effect intensity controls
• record/ playback sequencer
• "harmony arranger" (some kind of chord sequencer?)
• PCM sound generator like SA-series instruments.
• complex multi-chip hardware:
• CPU= "NEC D911GF 003, 9243AA005, Japan" (120 pin SMD)
• DSP?= "OKI M6583-04, 2432202, Japan" (60 pin SMD)
• DRAM= "Toshiba TC51832APL-85, 9236HAK, Japan" (28 pin DIL, 32KB pseudo-static)
• op-amp= "XRAI5218, 245 214A" (8 pin DIL, PCB label "M5218APR")
• power amp= "Motorola AN8056, 2'D6" (28 pin DIL)
• 3x resistor array= "B9HC0118, 101Kx8, 2N" (9 pin SIL, PCB label "CNB8X101K")
• resistor array= "B9XC0118, 101Kx7, 20" (8 pin SIL)
• 6 fusion/ synth pop demo tunes
• uncomfortable headphone- style microphone
• microphone jack (mono), phones jack

eastereggs:

• This instrument can make even stranger noises by feeding its own sounds through the microphone back into the voice changer. The results are e. g. very eerie, droning, booming and disharmonious noises those can be compared best with the horror movie music that Oskar Sala composed on the instrument "Mixtur- Trautonium" (but the "feedback" effect can do some similar sounds also internally). Also somewhat acid- like tweeting can be produced this way.

modifications:

• microphone headset bow was way to tight and almost crushed my head =>plastic bent under hot water to make it fit less uncomfortable.

notes:

It's a pity why Casio didn't make the keyboard note pitch freely playable through the "pitch sensor" without the 12 notes per octave rasterization. Also a simple sampling feature (like in the Casio SK-1) would have extended the capabilities of this instrument a lot, and the keyboard should be longer than 32 keys.

Someone now fortunately e-mailed me the manual of this instrument and explained how the "harmony arranger" works. This is what he wrote about it:

I bought this recently and found that I was quite disappointed in it till I tried the harmony arranger.  When you record your solo and press the 'harmony arranger' button, the keyboard creates the backing track with all the chords.  You can refine the tune by pressing the 'melody quantize' button which then moves the notes to the nearest precise timing (if that makes sense).  I was amazed that on my first attempt at using this feature, I had created a nice little tune with my fumbles on the keyboard :)  It's great for working things out very quickly.

hardware details The Casio VA-10 is based on the CPU "NEC D911GF 003" with 32KB external RAM "Toshiba TC51832APL-85" and an IC "OKI M6583-04" that may be a DSP. The double sided PCB is fairly complex with 3 large digital ICs and plenty of discrete components. The CPU "D911GF" is such exotic, that not even Google finds its name. As expected, also the "OKI M6583" has no datasheet, but plenty of Mitsubishi ICs with "M6583..." (different pin count) are audio delay DSP for reverb and echo effects in things like karaoke machines, so technical relations would be very plausible. (Yet I haven't analyzed the hardware further.)

A far relative of VA-10 was the unique fullsize midi keyboard Casio CTK-1000 ("IXA Sound Source" with digital effect buttons, similar design, velocity), but the hardware uses larger ICs and no related parts.
 

removal of these screws voids warranty...
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