Casio Rapman RAP-10 (rap soundtoy)

Wow, a grovebox-wearable with voice effects? How exciting is this?! Unfortunately nope. This soundtoy of 1992 was the most boring thing of Casio's Rapman series. It has no voice changer, but only 10 preset hiphop rhythm patterns and a fake scratch disc.

The sounds on the 4 drumpad buttons can not be changed. The disc simulates 2 button presses (one per direction) and can be switched among 5 variations (each 2 sounds) by corresponding buttons. This noisemaker has a strange shape (logo is upside down) because it was designed to be worn on a belt. The microphone input only plays through the speaker, which is a bit pointless without effects. Of the 5 step volume control one is too quiet and the rest earsplitting loud; fortunately it has a headphone/ lineout jack.

main features:

  • built-in speaker
  • 10 OBS preset rap rhythm patterns (some with fixed key accompaniment)
  • tempo +/- buttons (26 steps)
  • volume slide switch (5 steps)
  • 4 drumpad buttons {base, snare, "clap your hands!", orchestra hit}
  • fake scratch disc (simulates 2 button presses)
  • 5 OBS scratch variations {scratch hi+lo, "hit it!"+"clap your hands!", ping+orchestra hit, vocoder hi+lo, heavy metal guitar hi+lo}
  • CPU= "OKI M6521-08, 212009, Japan" (60 pin SMD)
  • jacks for phones, microphone

    • eastereggs:

  • 12(?) preset rhythms select button addable.
  • different scratch variation addable (likely multiple, very glitchy).

    • notes:

    This disappointing toy was perhaps interesting in 1992 as a novelty, when it was still uncommon to push some sound buttons and mess with a scratch disc like a DJ while singing through a belt mounted speaker (design patent USD342274). But as an instrument it is just boring, because without voice changer and keyboard it lacks everything that made the Rapman RAP-1 halfway enjoyable to play. RAP-10 is the silliest misuse of SA-series hardware beside the alarm clock TSA-90. The botched software wastes a sophisticated sound CPU, which in other keyboards could handle 100 preset sounds, but in this piece of poop can not even assign sounds to its own drumpads.

    Interesting is that in some rap patterns the drumpads (but not scratch disc) mute the drums for 1 bar. The "clap your hands!" drumpad and the scratch disc are duration sensitive and truncate their sound when released.

    The user interface has strange quirks. So the rap patterns only work with power switch in "rap" mode, which disables the scratch disc (sounds only a click) while no pattern is playing. Despite the patterns are on individual OBS buttons, you need to press "stop" before you can select another, because like in RAP-1 the CPU misuses parts of the PT-88 "auto play" algorithm to implement the rap mode.
     

    circuit bending details

    The Casio RAP-10 is based on the CPU "OKI M6521-08". There is no voice changer. Like other Rapman variants it is derived from PT-88 hardware, but here the software got particularly badly mutilated.

    keyboard matrix

    The RAP-10 is derived from Casio PT-88 hardware in a very hacky way, which causes many quirks. The 10 yellow buttons are technically keyboard keys, but their mainvoice sound was removed to stay mute in "play" mode. Up to 12 preset rhythms, a drumpad and more scratch variations (very buggy) can be added.

    This matrix was analyzed by myself with the help of service manuals of Casio ML-2, ML-3, ML-1.
     
    31 KI0
     32 KI1
     33 KI2
    34 KI3
    35 KI4
    36 KI5
    37 KI6
    38 KI7
     
    CPU pin
    in 0
    in 1
    in 2
    in 3
    in 4
    in 5
    in 6
    in 7
    in / out
     
    P.
    scratch lo
    (R. F3)
    P.
    scratch hi
    R.
    '1'
    (R. G3)
    R.
    '2'
    R.
    '3'
    (R. A3)
    R.
    '4'
    R.
    '5'
    (R. B3)
    R.
    '6'
    (R. C4)
    out 0
    39 KO0
    R.
    '7'
    R.
    '8'
    (R. D4)
    R.
    '9'
    R.
    '10'
    (R. E4)
    (R. F4)
     
    (R. G4)
     
    out 1
    40 KO1
    (R. A4)
     
    (R. B4)
    (R. C5)
     
     
     
     
    out 2
    41 KO2
     
     
     
     
     
     
     
     
    out 3
    42 KO3
    P. 3
    (clap yo hands!)
    P. 4 (orchestra hit)
    P. 1
    (base)
    P. 2
    (rimshot)
    P. 5 (2=vocoder hi)
    P. 6
    (rimshot)
    P. 7
    (base)
     
    out 4
    43 KO4
    O.
    'A'
    (N. '0')
    O.
    'B'
    (N. '1')
    N.
    '2'
    O.
    'C'
    (N. '3')
    N.
    '4'
    stop
    tempo
    +
    stop
    out 5
    44 KO5
    O.
    'D'
    (N. '5')
    N.
    '6'
    N.
    '7'
    N.
    '8'
    O.
    'E'
    (N. '9')
    P.
    variation
    R.
    select
    tempo
    -
    out 6
    45 KO6
    M.
    melody guide
    M.
    melody guide 2
    M.
    melody guide 2
    M.
    melody guide
    M.
    any key
    M.
    rap
    M.
    play
    polyphony 3
    [diode]
    out 7
    46 KO7

    The input lines are active- high, i.e. react on +Vs, thus any functions are triggered by a switch in series to a diode from one "out" to one "in" pin.
     

    legend:
    O.
    		 = scratch variation preset sound
    R.
    		 = rhythm/pattern
    N.
    		 = number entry (cipher buttons)
    P.
    		 = drum-/effect pad
    M.
    		 = mode select switch
    orange
    background     		 = easteregg (unconnected feature)
    grey 
    background    		 = unconnected doublet

    Compared to other PT-88 variants the tempo +/- buttons in RAP-10 are swapped. It is unknown if this should simplify the PCB layout of the mostly diodeless matrix or resulted of a programming bug. Also here there is activity on the LED matrix pins.

    eastereggs

    Like in Rapman RAP-1, also here the broken "melody guide" and "any key" modes exist. And even connecting the (here absent) polyphony diode at KO7->KI7 does a subtle change, namely that drumpads keep working with both scratch disc contacts closed, which normally stays mute.
    • rhythm select

      • Up to 12 additional rap rhythms can be added by connecting a rhythm select button at KO6->KI6. Unlike the normal ones, these rhythms contain no accompaniment. The select mechanism from PT-88 would use the 12 leftmost white keys, but only 7 of them correspond to scratch disc directions and cipher buttons of RAP-10. So for the rest 5 buttons need to be wired in row KO1 and KO2. (I have marked them in the keyboard matrix from theory, but haven't tested if they are correct. Unused keys are omitted although the full upper 4 matrix rows exist.)
    • drumpads

      • 3 additional drum-/effect pads (KO4->KI4..KI6) and variation button (KO6->KI5) can be added. But new are only the vocoder sounds (those already exist in scratch variations). The sounds on drumpad places (normal | variation) are:

      KI0: "clap yo hands!" | rimshot
      KI1: orchestra hit | base
      KI2: base | (mute)
      KI3: rimshot | vocoder lo
      KI4: (mute) | vocoder hi
      KI5: rimshot | orchestra hit
      KI6: base | (mute)
      KI7: (mute) | (mute)

    • scratch variations

      • Unlike the normal Rapman (see here), the scratch disc of RAP-10 is not implemented as 2 drumpads but wired to matrix places of the 2 leftmost keyboard keys, and the scratch variation buttons correspond to cipher buttons for selecting main voice preset sounds. There are 5 unused matrix places in row KO5 and KO6, but only a button at KO5-KI2 selects something (low orchestra hit | distorded snare?), and using this button again stays mute. The other 4 are mute and tend to mute the disc entirely, but combinations may do more interesting things. (I didn't examine this further.) Knowing the Casio KS-02 OBS buttons behaviour (see here), this hints how insanely crude the scratch variations are implemented.
      That is to say, the RAP-10 runs always in a keyboard drumkit mode. So each scratch variation (including the onw it powers on with) selects a different keyboard drumkit, which consists of only 2 sounds assigned to the leftmost 2 keys (those are the scratch disc) and the rest (including yellow buttons) is unassigned (mute). In "rap" mode (corresponding to PT-88 "auto play") the keys 3..12 select fixed-key preset accompaniment patterns implemented as songs, but keys 1 and 2 have none, hence turning the disc with no pattern selected produces a click, which also happens when connecting other non-existing keys above 12. This terribly botched software may be the only reason why the slide switch needed a separate "rap" and "play" mode, although pressing no yellow button or using "stop" could have serverd this purpose as well and so the user interface could do without.

    DJ soundtoys with poorly working scratch disc are a strange species. An intriguing example of their summit was the Potex Ultra-Mixer.
     

     removal of these screws voids warranty...    
    WarrantyVoid
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