CASIO
SYMPHONYTRON 8000		 modular stage organ

The Casio Symphonytron 8000 was an ultra-rare modular stage organ made in 1984. I read that only about 100 specimen were built. Its consonant-vowel hardware was related to Casio MT-65 (see CT-410V) with similar sound style.


(brochure photo)
I own only some of the components of this huge machine, but downloaded the manual and brochure. The complete expandable organ system was assembled from the following detachable units:

(brochure pictures)

A smaller expansion level used only one CT-8000 on the stand CS-100. The CT-8000 could be also used separately with an external amp; there was even a hard carry case HC-11 made for it. RC-1 and MB-1 are powered by the CT-8000 and can not be used separately.

some features:

notes:

The silver metallic painted system was heavy and quite a mess of plugged cables since it lacked a clever multicore or bus concept. Furthermore it was infamous for its flimsy combo amp speakers, those thin pressboard cabinets crumbled apart by rough handling or humidity, which made it not really stage-proof. Not least because it came out during the end of the home organ hype, it was a commercial flop, and so (similar like Commodore C65) only few demonstration specimen were built.

The Symphonytron had 49 preset sounds (in each keyboard) and the monophonic bass pedal keyboard had 18 keys and preset sounds. The accompaniment unit had 16 preset rhythms. The lower keyboard was also used for accompaniment. The voice of the lower keyboard could be layered with the upper keyboard, and both keyboards also could be detuned and transposed against each other for additional sound variation. With 2 keyboards present, there was an additional harmonizing mode (likely layering both keyboard voices in a special way). You can also combine rhythm with manual chord etc.; the accompaniment was similarly versatile like with Antonelli 2495. (Note: Despite the "8" in its name, the Symphonytron 8000 and its CT-8000 keyboard unit had neither a ROM-Pack slot nor key lighting.)

I got on eBay only one CT-8000, the RC-1 and a defective MB-1 in very beaten up condition (full of scratches, dirt and glue residues). Because it lacked the special DIN14 data cables, I ordered 3 Atari ST floppy cables, those work perfectly with the RC-1 (with one keyboard it does key split accompaniment with arpeggio, and also the trio mode works). How ever my MB-1 doesn't work at all. Also CT-8000 and RC-1 contain (as the only Casio instruments I know) each a soldered eprom; I backed up all 3 to avoid data loss. The multi-chip hardware is quite complex and particularly the RC-1 and MB-1 have several stacked PCBs in their crowded case. Fortunately there are are some pinout marks on them, those may help to decipher them. The MB-1 and CT-8000 both have the same CPU "NEC D8049C 364" (Intel MCS-48, I dumped its firmware) with sound IC "D931C 011". The RC-1 accompaniment CPU is a "NEC D930G 011" (controlled by an external CPU). So they are far relatives of the Casio MT-65 hardware class (technically closer to Casiotone 7000). I don't own the FK-1 pedal board, so I have no clue what is inside. Other people know more about this.

The Symphonytron 8000 has been partially emulated in MAME.

Casio CT-8000

The keyboards of the Symphonytron system can be also used separately (although they have no speakers). Their user interface resembles Casiotone 201 and 202 despite newer hardware.

main features:


The CT-8000 seems to be the only Consonant-Vowel keyboard that apparently layers 2x D931C in its preset sounds for having 2 differently filtered subvoices like in earlier models. Like in Kawai MS20, when you set a preset sound on the keyboard it sounds a short fanfare with it (always the same notes). The CT-8000 also contains 2 DC voltage output jacks for supplying the RC-1 and MB-1.

Casio FK-1


(brochure photo)

This is the Symphonytron bass pedal unit. I don't own this.

main features:

Casio RC-1

The accompaniment unit is the central of the Symphonytron system, where the data cables of all other components are plugged into. Rhythm and accompaniments resemble Casio MT-65 (see CT-410V). It has complex patterns with arpeggio including triplets. The good quality semi-analogue percussion has several congas. The bass voice sounds nicely warm.

main features:


battery compartment
The RC-1 has a compartment for 3 AA batteries to supply the SRAM that holds registration and sequencer data.

When only one keyboard is connected (no matter if in "upper" or "lower" jack) its leftmost keys can act as "lower" keys for chord section, that ends on key 18. This splitpoint can not be changed, but switching chord mode off returns all keys to its internal main voice. The bass and chord voice is produced inside RC-1 and sent through lineout. But to make this work, the MB-1 unit needs to be plugged in with data and power cable connected. So the RC-1 and MB-1 seem to depend on each others in unobvious ways, despite my MB-1 doesn't work.

Casio MB-1

This is the sequencer unit of the Symphonytron system. Mine likely is broken.

main features:

The small device is stuffed to the brim with 5 doublesided PCBs with its own sound generator, 4 hybrids and plenty of logic stuff.
The editable polyphonic realtime sequencer recorded all sounds (947 steps in total, 58.5 steps of these only for function select events, all of them shared among up to 4 songs). It could save them to the RAM-Pack RA-2, which looks like a white version of the Casio RA-5 of Casio CZ-101 and related instruments.

My MB-1 doesn't work. The LEDs flash for a fraction of a second during power on, but buttons don't respond and through lineout it produced a sort of hum with fluctuating intensity that sometimes turns into a louder growing digital buzz. Possibly the eprom is dead. But the MB-1 still does something important, because the chord keysplit of RC-1 works only so long the MB-1 is connected and powered. My data cables (3 different) are from Atari ST diskette drives, so some pins for MB-1 may be simply miswired; for connecting the keyboard they work ok.

I first thought that it may need a complete Symphonytron system (with 2 keyboards and pedalboard) to function properly, but the ad of the keyboard stand CS-100 depicts a configuration like mine (1x CT-8000 + RC-1 + MB-1), which shows that Casio supported this combination. Unknown is why the MB-1 contains its own 2 sound ICs D931C; likely it was supposed to playback a track without reducing the 8-note polyphony of the keyboards. I saw no RAM inside my MB-1, so I think it uses those 4KB of the RC-1. The manual mentions, that the MB-1 could copy a song from one RAM-Pack to another, i.e. it is read into system RAM for use.
 

Casio RAM-Pack RA-2
 
The RA-2 is the Symphonytron RAM-Pack, which looks like a white version of the Casio RA-5 for CZ-101 and related instruments. The capacity is 4KB.
Originally a 3V lithium button cell "BR2016" was installed, but a stronger "CR2032" fits as well because the case lid presses it on the contacts. The case is closed with 3 screws. Inside are 2 SRAMs "Toshiba TC5516AFL" (24 pin SMD, each 2KB), a logic IC "T 40H000F" (14 pin SMD), a diode, 2 capacitors (10uF electrolytic, 10pF) and 2 resistors. Most pins are wired through carbon traces as resistors, those may be current limiters if 3V powered SRAMs are connected to a 5V bus.
 
 removal of these screws voids warranty...    
WarrantyVoid
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