Say & Play Keyboard CASIO SK-60

lo-fi sampling keyboard with vocal percussion & sound effects

This instrument from 1996 (PCB stamp "MAY 22  1996") was AFAIK the last small sampling keyboard made by Casio. Although it was more designed like a toy than the other SK series keyboards (there is e.g. no sound output jack), it is one of the more interesting ones, because it features various special sound effects.

Spectacular are especially the many (Fairlight CMI style) singing human voice sounds and accompaniments those can be switched into vocal percussion mode by the "magical singer" button. Also the demos use many vocal accompaniments and reminds gospel or blues choirs. There is also various wicked tekkno siren stuff on this instrument that significantly differs from the SA series keyboards, and there is a drum kit mode with sampled vocal percussion sounds (known as "beatboxing" in the hiphop scene). The SK-60 can sample up to 4 short samples those can be assigned to the 4 effect pad buttons. When the "pad effect" button is pressed, each pad modifies its sample in a specific way {chorus, ring, pitchbend up, pitchbend down} with much zipper noise. In "cycle" mode it plays the samples in a sequence (one per key press). Instead of 4 short, also 2 longer or 1 long sample can be recorded. Unfortunately the accompaniments play their own fixed melody line and thus are badly suited for melody play, but they are nice to improvise to and sound quite inspiring.

main features:

notes:

This instrument is quite unusual because despite it was obviously designed as a toy (with neither microphone nor sound output jacks), it has unusually high polyphony (about 16 notes?) because it was based on modern sound hardware that Casio also uses in non-toy keyboards.

The preset sounds are made from medium resolution loop samples and most sound fairly realistic. The sound engine differs significantly from the classic Casio SA series wavetable hardware because it has not only higher polyphony but also has a much higher tempo resolution and employs neither chorus nor reverb nor echo effects in its sounds. The volume control here also affects held notes, but selecting a new preset or sample sound does not change them.  Fortunately also button presses play no unnecessary noises anymore and there is also no battery alarm or similar.

The "piano" sounds quite realistic. The "elec piano" resembles a Rhodes piano. The "organ" is a plain Hammond organ tone with percussive click. The "guitar" is an acoustic one. The "vibraphone" has only very weak vibrato. The "violin" sounds quite harsh with weak delayed vibrato, while "strings" seems to be rather a loop sample of a string orchestra than a synthetic chorus sound. "trumpet", "clarinet", "flute", "sax" have a slow vibrato. The "siren 1" is a fast howling and slowly louder fading siren. "siren 2" is a slowly louder fading ambulance siren which pitch goes down and fades silent after key release (like being overtaken by an ambulance). The sounds "telephone", "space 1", "space 2", "funny" are nice tekkno effect split sounds those are different from the SA series; unlike with SA series keyboards, here all keys play different pitches. "telephone" = {phone toot, digital phone ring, pulsed digital phone ring(?), engaged tone, short sine beep}. "space 1" = {slowly down and up wobbling pulsed siren, faster up howling siren, up and down howling glissando siren}. "space 2" = {digital phone ring layered with pulsing bass, pulsing bass toot followed by up howling siren that fades silent}. "funny" {wobbling siren varying pitch amplitude, sequencer loop pattern of 3 tones}. The "human voice" sounds are short loop samples with delayed vibrato and remind much to historical Fairlight CMI sample choirs. "aah" and "ooh" sound like a children choir. "bah (bass)" is a male voice with strange fluttering loop point. "voice percussion" is a drum kit mode with voice and snap sounds: {"guer!" (male), imitated snare (or analogue transistor noise snare?), "sh!", finger snap}; all sounds can be played on a few different pitches. The "human voice (cycle)" sounds are sequences of 2, 3 or 4 of the normal "human voice" sounds; every new key press starts a new sample of the sequence. The same thing can be also done with the 4 user samples. (This concept may be a crude predecessor of the professional Roland VariPhrase hi-end sampler keyboards.)

Instead of normal rhythms there are only so-called "free sessions", those are basically like demo songs without main voice those can be improvised to. This concept resembles much the "jam tracks" on Yamaha PSS-6 or PSS-31, except that the main voice preset is not automatically changed during the track, but only during selection of a "free session". (Each has one corresponding default preset sound.) Interesting is that many of the accompaniments include voice samples, and with the "magical singer" button also the rest of the percussion sounds is replaced by voice percussion and also the main voice by a human voice sample. (All samples are taken from the main voice presets.) Pressing the button again switches rhythm back to normal drum kit percussion and the main voice to the default preset sound of the current "free session". By the many vocal accompaniments the musics remind much to gospel or blues choirs.

Also the first 11 of the 24 demo songs employ vocal sounds, while the rest can be switched to vocal mode with the "magical singer" button. The 24 demos are:

  1. Voices of Reason (original song)
  2. Twinkle Twinkle Little Star
  3. Dooin' My Thing (original song)
  4. Ode to Joy
  5. Little Brown Jug
  6. Spring from "The Four Seasons"
  7. When the Saints Go Marching In
  8. Frère Jaques
  9. Old MacDonald Had a Farm
  10. Auld Lang Syne
  11. Londonderry Air
  12. Row, Row, Row Your Boat
  13. Mary had a Little Lamb
  14. Amazing Grace
  15. Ach Du Lieber Augustin
  16. London Bridge
  17. Joy to the World
  18. Greensleeves
  19. Jingle Bells
  20. Silent Night
  21. O Christmas Tree
  22. Yankee Doodle
  23. Santa Lucia
  24. March from "The Nutcracker"
All demo songs can be simultaneously accompanied on the keyboard, and with the "melody on/ off" button their  melody voice can be optionally muted and re- enabled at any time.

By the lack of an input jack, the sampler can be only fed through the internal microphone. Samples can be tuned, reversed or looped. Each sample can be tuned, reversed and repeated in a loop. Instead of 4 short samples also 2 longer or 1 long sample can be stored by selecting "time" {S, M, L} (which erases the sample memory). Up to 4 samples can also play in a sequence (each key press plays the next one) by selecting the "cycle" functions. All sampling edit functions are selected through white keys + "edit" button. The 4 samples are automatically assigned to the 4 rubber pad buttons {A, B, C, D}. Interesting is that the pads always add a simple envelope, thus the sample is only played to the end by holding down the pad, while a short press only plays the begin of that sample. With the "pad effect" button the sounds from the pads are sent each through a fixed default effect: "A"= chorus, "B"= strong square vibrato, "C"= pitchbend up, "D"= pitchbend down. The chorus resembles rather a cold and disharmonic dubbing. The square vibrato rings disharmonic with about 5Hz like a digital telephone ring. The pitchbends bend up or down by about an octave during a second; they make a lot of zipper noise and thus resemble more a portamento than a glissando. Unfortunately apparently neither the order of the effects nor of the samples in the memory can be changed, thus to apply a different effect to a sample is not possible without recording it again on a different sample number (erasing the previous one on that number).

After power- on, the 4 pads are always assigned to the 4 "voice percussion" sounds {"sh!", snap, "guer!", pseudo- snare}. As soon any sample is selected or the "pad effect" button is pressed, the pads are switched to the 4 samples and can not be switched back to "voice percussion" without switching the instrument off. With no samples in memory, the pads are instead assigned to {"doo (female)", "be (female)", "dee (female)", "bah (female)"}.

Important: I have no manual for this instrument, thus there may be some features I don't know.
 

hardware details

The Casio SK-60 is built around the CPU "OKI M6755B-10" with external 32KB RAM.
This is the only SK-series instrument that is not based on the M6238 CPU. Despite fewer ICs it has unusually high polyphony (12 notes) because it was based on modern sound hardware that Casio normally used in non-toy fullsize keyboards with songbank and often keylighting (like CTK-220L and LK-30).

This analysis is based on the Casio SK-60 service manual.

keyboard matrix

This keyboard matrix is based on the Casio SK-60 service manual. I haven't analyzed it by myself, so there may be still unknown eastereggs. Each KI# pin at the CPU has a 2.2k resistor and each KO# pin a 1k resistor in series. 

The KO pin numbering is shifted by 1 versus the CPU pin name in schematics (i.e. CPU pin KO1 is KO0, KO2 is KO1 etc.) which is likely a service manual bug, because in other keyboard schematics they start correctly with KO0.

The matrix layout (e.g. button positions) strongly differs from other keyboards with M6755x CPU, which hints that it is not derived from the same software and won't include their eastereggs.
 
58 KI0
59 KI1
60 KI2
61 KI3
62 KI4
63 KI5
64 KI6
65 KI7
 
CPU pin
in 0
in 1
in 2
in 3
in 4
in 5
in 6
in 7
in / out
 
o
F3
o
C#4
o
A4
o
F5
P.
'A'
sample
'1'
N.
'1'
song
out 0
66 KO0
o
F#3
o
D4
o
A#4
o
F#4
P.
'B'
sample
'2'
N.
'2'
start/stop
out 1
67 KO1
o
G3
o
D#4
o
B4
o
G5
P.
'C'
sample
'3'
N.
'3'
melody 
on/off 
out 2
68 KO2
o
G#3
o
E4
o
C5
o
G#5
P.
'D'
sample
'4'
N.
'4'
tone
out 3
69 KO3
o
A3
o
F#4
o
D5
o
A#5
volume
+
magical singer 
N.
'5'
 
out 4
70 KO4
o
A#3
o
F#4
o
D5
o
A#5
volume
-
sampling
N.
'6'
 
out 5
71 KO5
o
B3
o
G4
o
D#5
o
B5
tempo
+
edit
effect
 
out 6
72 KO6
o
C4
o
G#4
o
E5
o
C6
tempo
-
 
 
 
out 7
73 KO7

The input lines are active-low, i.e. react on GND. Any functions can be triggered by a non- locking switch in series to a diode from one "in" to one "out" pin.
 

legend:
"o"
 = keyboard key
underlined
 = function needs locking switch (i.e. stays active only so long the switch is closed)
N.
 = cipher buttons
P.
 = drumpad
orange
background		 = easteregg (unconnected feature)
grey
background		 = unconnected doublet

Predecessors of this instrument include the Casio SK-1 (first Casio sampler, great synth features, blip percussion), SK-5 and SK-8 (with ROM-Pack, key lighting, upgradeable as oriental keyboard) those all have interesting features, but none is really similar like the SK-60. Much info about Casio SK instruments can be found on the internet.
 

 removal of these screws voids warranty...    
WarrantyVoid
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