RAMASIO 892 small full polyphonic analogue keyboard with great accompaniment

You certainly know keyboards from Casio, but did you ever hear a Ramasio?
 

The blue writing "electronic keyboard" was retouched; in reality it was almost invisible on the photo.

This bizarre and great sounding keyboard is technically something extremely unique, because on the one hand it is a small midsize instrument with COB (black blob) CPU for the main voice, while on the other hand it is full polyphonic with monophonic piano envelope - a technology that normally was already abandoned in the beginning of 1980th.

The sound of the Ramasio 892 is made from sonorous mixed squarewaves with a nice warm and bassy analogue timbres. Also the percussion is analogue with transistor noise and sound quite unique like the rest of the instrument. Interesting is the unusual full polyphonic fingered chord accompaniment, which permits various play tricks and responds so rapidly that it even accepts trilled notes and not only plays non- chords but even weird grunting cluster patterns. Unlike the simple accompaniment of Antonelli Star 2379, this one even includes walking bass patterns and can do single finger chords.

(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 keyboard those timbres sound not remotely like what is written on its switches, though bought with wrong expectation it may disappoint you. Also the monophonic envelope behaves very different from normal polyphonic keyboards.)

This instrument was also released as an unbranded version (no type label on case; here named RJP 892).

main features:

eastereggs:

notes:

The hardware of this thing is really bizarre, because despite it is full note polyphonic it employs a keyboard matrix with diodes, controlling a separate sound IC by a CPU. I never saw a hardware architecture like this. The main PCB contains much discrete analogue stuff (mainly percussion).

caution: The rubber contacts under the keys are not silicone and can decompose by things like ozone, UV light, oil or battery leak vapours. For protection store this instrument without battery in an airtight PE or PP plastic bag away from direct sunlight.

The main voice is made from 5(?) mixed squarewaves with monophonic volume envelope and sounds pleasantly warm and bassy. The timbres "organ" , "flute", "horn" use the same envelope (slow attack phase like a pipe organ, tones end with a click when released). "organ" resembles the famous sonorous multipulse pipe organ  timbre, "flute" is plain squarewave, "horn" is a duller muffled multipulse timbre. The "piano" sounds not remotely like expected; it is simply the "organ" timbre with additional monophonic envelope that fades quieter, but unlike a real piano it has a way too slow attack rate (like "organ"), fades quieter too slow and even never reaches silence but stays on at low volume, thus with held notes it basically it sounds like short pipe organ notes with much sustain. After key release it immediately ends with a quiet click. Due to the envelope is monophonic, the tones of all currently held keys sound again at full volume as soon a new key is pressed. All timbres contain a weak and fast vibrato that can not be switched off, and the internal vibrato trigger pulses crosstalk as a quiet fast ticking in all sounds (particularly strong during decay phase of the "piano"). There is no sustain switch. The multipulse-like waveforms are genuinely made by mixing tones of different octaves; by setting the preset sound slider into intermediate positions between "organ" and "flute" or "flute" and "horn", 2 additional such timbres come into being those are mixed from the 2 adjacent ones.

The analogue percussion sounds quite unique. While hihat and snare are made from transistor noise, the base is quite dull and sounds like knocking on cardboard or the like. The special sound is the snap, which is a high, thin and rather loud percussive bang, that resembles finger snapping or a tiny exploding firecracker. I don't know if the manufacturer intended it do be a clave, but it doesn't sound at all like one. All rhythms contain a fast quiet ticking, that is likely the vibrato trigger pulse mixing itself into the transistor noise sound. The tempo slider can be set very slow but not really fast (unless you modify it - touching the sound IC (clock pin?) increases tempo to tremendous speed).

The accompaniment always starts the rhythm, thus there is no manual chord mode, but otherwise it is greatly versatile playable and sounds unique. The automatic accompaniment patterns consist of a bass line (playing the leftmost and rightmost of the currently held accompaniment keys) and a polyphonic piano chord (with the notes of all held accompaniment keys). Both employ a capacitor envelope for decay. With the "bass" button the bass line can be switched to a more complex walking bass pattern. Great is that the accompaniment itself does not hold any notes, thus it responds so rapidly that it even accepts trilled notes, and instead of a chord you can play even any weird disharmonic note clusters those get also gated by the accompaniment into a wildly grunting sound. Like a Hammond organ, the accompaniment notes start and end with a noticeable quite click during all key presses. Also the accompaniment patterns are partly unusual and contain strange fluttering dual note trills. When accompaniment is started by pressing the chord "on" button and chord "memory" is not active, the rhythm with accompaniment plays only so long any key in the accompaniment section is held down. It stops by releasing these keys and always restarts the pattern by pressing an accompaniment key. This way some weird breakbeat stuff can be played by trilling on the keys. When rhythm instead was started with rhythm "start/ stop" or "synchro", the rhythm stays on with keys released. When "memory" is pressed, also the accompaniment continues with its keys released. The "auto / manual" button enables the single finger chord mode (accepts only minor and major chords?).
 

hardware details

The Ramasio 892 is based on the COB CPU "5851-541, 260D6" with separate drawbar sound IC "TMS3630NS".
pcb logo: 'RJP'On the main PCB is a logo "RJP", which is a company that in 1970th made LED pocket calculators and apparently later only toy keyboards. E.g. they made the "MU-781 Sound Mix Organ Karaoke" (with cassette recorder and effect sounds like Bontempi - Disney Band, I own one), the RJP MU-7986 and the "RJP 896 Programmable Guitar Organ" (grey case resembling  Yamaha SHS-10, seen on eBay).

The CPU has only 23 pins although there are 37 keys connected to it and there are no additional logic ICs. (Touching both pins of the big blue foil capacitor on the CPU COB module makes the thing ignore key presses without stopping the sound.) The concept of integrating classic full polyphonic technology into a COB IC (those are nowadays only found in cheap digital stuff like My Music Center) appears quite absurd to me, but basically the many fake Nintendo NES/ FamiCom 8 bit game consoles also contain this way redesigned historical hardware. According to a japanese webpage by morian, the TOS sound IC seems to contain 5 drawbar channels {4, 8, 16, other code (aka programmable?), base} and is controlled through a 4 bit bus.

On the panel PCB (which also contains the amplifier) hangs loosely on 4 thin wires a small daughterboard with 2 transistors and many discrete components, which seems to contain the timbre filter for the main voice (touching it makes sound duller); Traktor told me that his unbranded RJP 892 lacks this. Despite analogue percussion there are no trimmers beside the tuning one on the PCB, which is strange because even cheap analogue keyboards like Angeltone DM-380 normally have percussion decay trimmers. Like all analogue instruments, also this one can be certainly easily modified in many ways. (Be careful with the flimsy foil ribbon cables between the PCBs.)
 
Initially one key didn't work well; my specimen apparently had been exposed to heat (e.g. left in a car in summer) because also the caps of the slide switches and potentiometers are warped and thus sit tilted instead of straight. The rubber contacts under the keys seem to be made of something different than silicone; their black centers were partly greyish discoloured and some rubber caps were crushed (from misplaced installation?) and sticking to itself at the folded edges (which doesn't happen with silicone). Although mine still worked and I could free them again, when the folded membrane would not have been found, they may decompose over time (especially by ozone in the room air or battery leak vapours). By smell I guess they are of butyl rubber, which tends to be as vulnerable as latex, thus be careful not to bring oil (except silicone) or any other fatty substances in contact with these, which would likely dissolve the rubber. (Traktor's specimen crumbled apart by battery leak.) It may be also a good idea to store this instrument in an airtight PE or PP plastic bag to protect the rubber from airborne ozone and phthalate.

drawbar synthesis

Traktor told me that the preset sound switch uses 3 contacts to mix 3 drawbar tones from the sound IC through different resistor combinations. Thus certainly potentiometers can be installed here for real drawbars.
 
preset sound: 16' 8' 4'
piano 10k 22k 22k
organ 10k 33k 47k
flute   18k  
horn 10k   33k

The accompaniment data seem to be multiplexed with percussion trigger outs.

(I haven't analyzed the hardware further yet.)

The Ramasio 892 unfortunately is extremely rare; I only saw one other specimen yet, however I was told by e-mail that the RJP 993 (grey with yellow buttons, same preset sound & rhythm names) apparently had the same hardware. And Traktor told me that apparently a Danish variant by Star Mate with different case and mainboard (206D15 instead of 206D5) exists. A predecessor of the 892 was the Kamosonic KB-1000 (49 midsize keys, no envelope, no accompaniment (only manual organ chord keysplit)). A far relative of the 892 may be the midsize Jiaying Z4941. Another analogue keyboard with full polyphonic accompaniment was the way oversized Antonelli Star 2379. Also Antonelli 2495 permits similar play tricks. The strange monophonic main voice envelope exists also e.g. on Bontempi Minstrel Beta.

Question: Does anybody know other non-toy keyboards made by Ramasio or RJP?
 

 removal of these screws voids warranty...    
WarrantyVoid
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