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Casio CTK-650

GM-Compatible Keyboard By Julian Colbeck
Published April 1994

Sixteen‑part multitimbrality, 32‑note polyphony and a respectable set of GM‑mapped Tones join some usable and fun auto‑accompaniment, and an absurdly low price tag, in a 'home' keyboard that deserves some attention from the studio musician. Julian Colbeck just wants to have fun...

I've been asked to do some fairly odd things before, but I still nearly toppled off my perch when SOS called, shortly before I left for earthquake‑riven NAMM last month, to ask if I could review "this new Casio keyboard". Was this a wind‑up? Was that the editor snickering in the background, by any chance? It's not April, is it? These and other such thoughts swam in and out as your trusty assistant editor went on to assure me that, really, he'd heard it was good, and that it was perhaps about time that such comparatively low‑tech morsels were scrunched under the SOS microscope. Still I protested: "But this is still a home keyboard, you understand? You know, speakers, and styles and stuff." But DJ was having none of it. He wanted it reviewed and that was that. So, here it is: let the Beguine begin.

Worthwhile Home Keyboard Horror Shock

The CTK‑650 is made by Casio, purveyor of mass‑market, department store musical instruments, who, if you go back that far, had a brief but highly impressive fling with hi‑tech a few years ago, the love children from which — CZ series synths, FZ series samplers, PG10 MIDI Guitar — are still immensely popular items second‑hand. Casio might have slunk back to home base for the time being but it remains an inventive company, and one that clearly still employs hip designers and programmers.

The CTK‑650 is a home keyboard. No way of getting around this one. However, it is a home keyboard that not only breathes new life into its own, obvious, entry‑level home keyboard category (take a look at the price), but, I think, is capable of reviving anyone prepared to give it a few minutes of their time. Briefly consider this: full 16‑part multitimbrality, GM‑mapped sounds, full‑size, 61‑note, touch‑sensitive keyboard, plenty of excellent sounds, and enough genuinely musical tricks up its sleeve to keep all but the most jaded of old codgers (like me) happy for, well, hours. Unlike most home keyboards nowadays, which are obsessed by just two things — General MIDI, and faster, slicker, everything‑everywhere styles — the CTK‑650 offers GM compatible tones and hundreds of styles as starters, and then all manner of far more interesting things which you can go off and have fun with: crazy sounds, musical motifs on pads, grooves you can play (as opposed to just styles you can just listen to), automatic chord sequences for writing, and much more. And being sufficiently MIDI aware, you can, as indeed I have been doing this evening, simply plumb the CTK‑650 into the ST and interact with the beast on a more visually enlightening platform. Already I've constructed a killer groove. Using Notator to record a fairly pedestrian style, I simply matched the tempo with the CTK‑650 and subsequently removed all but the drums and then slowed them down. Then I looped it and stood it on its head by treating beat 2 as if it were beat 1 and copying it all across to another pattern so it then was beat 1; then I slid in a slinky little bass line using the instrument's blinding upright bass tone... and then figured I'd better abandon the whole escapade and get on with writing this. Darn it. And it was all so easy, too, since the instrument simply hangs about in multi mode anyway, so all you have to do is flip MIDI channels on the sequencer and/or lob in a program change. Whoa there, boy. Let's go back to the top, shall we? Forget about sequencers and all that stuff for a minute. Whatcha get for £400?

Back To The Top

The CTK‑650 is light. Too light for us serious fellas, really, but my back loves it. Moving quickly along from the irritation of an external PSU (which buzzes nastily; I hope this is simply a dodgy unit), you plug in and can immediately play the 5‑octave, full‑size keyboard. Now it's not a Steinway, you understand. But the feel and action is no worse than a whole host of synths and workstations five times this price, so it needn't hang its head in shame. It's velocity sensitive too. And you can tailor the response over three levels. What you can't do is invert the polarity of a connected sustain pedal, as I discovered to my cost as I smugly inserted my nice Roland sustain pedal.

All the 650's sounds are playable 32‑voice polyphonically, and you can layer or split any two anywhere. Even more surprisingly, you can have a split and a layer at the same time, with a single instrument in the left half and a double in the right. Just to clarify, the split point is completely assignable (press Split: hit a note). A note of interest — CTK‑650 sounds use the same advanced processor that Casio uses on the Celviano range of high‑end digital pianos.

Effects on offer include three reverbs, chorus, flanger, tremolo, phase shifter, enhancer, EQ, and Organ SP, which serves as a passable medium‑speed Leslie effect. I won't lie and say the effects exactly ooze quality — the reverbs do have a bit of a ring to them — but they are there, and they do help. The effects setting is global, though. In other words, once you set up an effect, it will be applied to all instruments. Since you can switch effects so quickly, this is only a mild irritation.

You'Ve Either Got Or You Haven't Got... Styles

There are 128 styles on board the CTK‑650, each with a variation, fill, intro and ending. Styles comprise rhythm and bass parts, plus two accompaniment parts played generally over only two bars, though skillfully so. Overall, the standard of programming is high, with some exceptional drum programming in particular, and plenty of unusual styles in general. Styles of note would have to include: Groove Pop, Fusion (with its attractive slide bass part), 16‑beat 2, Techno Pop, the boogie'n N'awlins Bar, Chicago Blues, R & B, Hip Hop, Rave 2, and some of the many ethnic styles like Sirtaki (a Greek rhythm), Guracha, Baion, Kivrak (full of eastern promise, and purring congas), and Zouk!? The chord recognition is good, without being spectacular, and you have a choice of Fingered (you play 'em), Casio (Casio plays 'em — you just prod the odd note), or Full Range Chord, which is a sort of pianist mode, whereby the instrument interprets what you are playing over the whole keyboard in order to make its chord selection. It works very well. Or you can switch it all off and just accompany the rhythms on your own.

A nice idea that I've not seen before is the CTK‑650's ability to mix and match style intros, variations, fills, and endings. In other words, you could set up the intro from Merenge to lead into the Zydeco style, for example. Some intriguing marriages can be brokered here. There is a small Play Sequencer, and you can balance the relative volumes of the styles to your own right‑hand playing.

So far, aside from the impressive range of sounds, the polyphony, and the multitimbrality, we could be dealing with any number of home keyboards. But from here on, the CTK‑650 ventures out into the comparatively unknown. For starters, there are four little buttons called Sound Pads that sit in the middle of the style panel. These activate a wide selection of musical motifs, riffs, and runs that you can randomly inject into your playing. The whole idea could be unutterably naff, were it not for the fact that some of these snippets are exceedingly well written, deliver over MIDI, and play at whatever speed is currently set on the tempo control. There are four pads and some thirty‑odd selections to choose from. The range of goodies includes things like brass flourishes, trills and rolls, a few bars of 'silent film' piano chase music, and various techno breaks and bashes. Cleverly, the last few selections implement sundry performance effects such as pitch bend or vibrato, which go some way towards making up for the fact that the instrument doesn't sport a pitch or mod wheel.

That's Magic

But this is only the beginning. Over on the left hand side of the panel is a whole series of features that come under the heading of, ahem, Magical Presets. These are simply a loose collection of features that turn the CTK‑650 from just another (though good) home keyboard into something special.

The first Magical Preset is Break Beat, which is a series of 16 patterns (not by any means all break beats, either — bit of a silly title really) that stop dead when you lift your fingers off the keys. This enables you to really play patterns, using descending bass lines, breaks, stabs, and so on. Probably the best place to examine it is on the Soul pattern, where you can 'play' the classic ascending run back into a typical four‑to‑the‑bar soul groove. This is as infectious as it is fun. The only complaint I have is that for reasons of time, I'm told, Casio were not able to make this section send out over MIDI. Wah! The shame of it is that you can play and write some interesting music using this device, and it would have been nice to be able to record the results externally. Since both the styles and the Sound Pads deliver over MIDI, this clearly would have been an option. Next model, I'm assured.

Melody Comp is the next Magical Preset, and this is a superb feature for non‑players, or nervous players who are bored with being idle observers as ever more slick and alienating styles whizz by. You hit a key and every time you re‑trigger a note an underlying chord changes. If you play legato, however, the underlying chord remains in place, which allows you to 'solo' over a chord freestyle, and then, by momentarily lifting your fingers off the keys, to continue the solo over another chord shape. This comes complete with bespoke sounds. It's one of those features far more difficult to describe than it is to play or work with. And it's great to listen to. Shadow Drum places a series of drum sounds beneath the notes you are playing. Most people, I'm sure, have done something like this from time to time, fading up, say, an internal sound on a keyboard that is triggering a drum kit. But here the drum sounds cycle on each individual note, so you have the chance to explore the possibilities for real.

Free Session has been seen before on Casio keyboards, but the range of programming and sounds here make this continual chord progression feature superb fun to use. Basically you have 30+ chord progressions to choose from, ranging from completely easy things like I, IV, V, I to substantial pieces of composition. These sequences are activated by the style stop/start button, are alterable in tempo, function in any style, and you still have complete control over the right‑hand sound. Well, this is brilliant. It means you can dial up and mix hundreds of grooves with chord progressions in order to develop some ideas, solo over, work on your chops, or just have fun playing to.

The next feature on offer, Tone Stack, is not just some boring tone‑layering facility (though plenty of good plain stacks do live here as well) so much as musique concrete, whereby a whole string of sounds have been glued together sequentially. Eat your heart out Wavestation and friends, this is right up there. Hyper Active takes this a step further, offering all manner of panning effects, and finally, a series of sounds that — as on Shadow Drum — cycle through a series of tones per triggered key. It's almost like having one of those early Oberheim 4‑voice synths! Unquestionably, the Magic Preset treasure chest will both amuse and instruct all but the most jaded and stuck‑up of musos.

In Conclusion

The CTK‑650 can be looked at on many levels, and before concluding, it is worth running through a few possible applications. For a start, this is an extremely low‑cost, velocity‑sensitive MIDI keyboard. With speakers. Its full multitimbrality and generous polyphony make it a good choice for someone on a budget who needs a sound source for external sequencing. You have a keyboard (local switchable off, of course), and plenty of raw material. GM playback is also quite feasible. You can switch to GM mode and everything then maps to GM. The only reason the CTK‑650 cannot brandish the GM logo is pitchbend assignments, and if your GM sequence uses a lot of pitchbend you may run into the odd hiccup. In terms of tones and polyphony, though, no problem. It checked out fine with a random selection of GM sequences I threw at it.

If you're using the 650 as a learning, songwriting keyboard, the styles and Magic Preset stuff should keep you out of trouble for an eternity. As mentioned, you can have enormous fun using the instrument for source material, recording the styles on an external sequencer and generally mucking about with them there.

The CTK‑650 is not flash. You won't look like a prune with this in your studio or bedroom. Just enjoy it for what it is: an extremely clever instrument for an extremely small amount of dosh.


KEYBOARD: 61‑note, velocity sensitive

TONES: 128 GM Sound Set

POLYPHONY: 32‑voice

STYLES: 128, with variations

EFFECTS: Reverbs, chorus, flanger, phaser, vibrato

SEQUENCER: One song at a time, real time


POWER: DC 9V (6 D size batteries, AD‑5 AC adaptor)

TONE GROUPS: (8 tones in each)

  • Pianos
  • Chromatic Percussion
  • Organs
  • Guitars
  • Bass
  • Strings/Orchestra
  • Ensemble
  • Brass
  • Reeds
  • Pipe
  • Synth‑Lead
  • Synth‑Pad
  • Synth‑SFX
  • Ethnic
  • Perc
  • SFX

CTK‑650 Tones

Tone 1 is a respectable acoustic piano. Up at the top it's actually more than respectable, with a spot‑on, undampened‑strings spaciousness to it. The middle lacks a bit of punch but is serviceable; the bottom is the only area of complaint, lacking anything in the way of grit or bite. There are 127 other tones, so please excuse me if I shirk my duty and simply give you a few edited highlights. The honky tonk sounds pretty good, which either means that I'm going senile — since I used to detest this type of sound a few years ago — or that this is in fact a useful chorused piano tone. A tone called 'Clavelectro' (what can they mean?) is nicely spiky and with the addition of some flanging — I haven't mentioned the effects yet, have I? — it's a bit of a winner. 'Electric Piano' isn't bad either. I liked the marimba, and the glock, even though it sounded more like rich bells to me. The dulcimer is full of character, and bandneon is absolutely vile — in other words, a very good rendition of this obnoxious Lambada‑reeking squeeze box. Steel‑string guitar is well executed, and the guitar harmonics would be fab if only there were some aftertouch vibrato around. The wood bass, as mentioned, is definitive, and even some of the strings — massed, pizzicato, and tremolo — are quite acceptable, especially if you splash a bit of reverb on them. The harp is very good indeed, as are many of the solo brass and woodwind tones. There's a splendid, burbling solo trumpet, a well‑defined oboe with just the right amount of delayed vibrato, a slightly fruitier English horn, and a French horn that works well played polyphonically, though the generic brass sounds are a bit weak. I liked the clarinet, the piccolo (which is far better than the flute), and the moody, haunting whistle. There are loads of 'synth sounds'; some of which, like the pitch‑enveloped 'Pearl Drop', are innovative and excellent. Finally, there is a bank of well‑executed ethnic instruments: a brilliant thumb piano, koto, shamisen, and the like.


For an extra £120, the CTK‑750 provides several possibly vital additions to the spec of the 650. These include a pitch bend wheel (no modulation), a more complete 'bass reflex' amplification system (not more powerful, though), a 6‑track sequencer with memory capacity of around 5800 notes, six additional effects (most notably delays), and two more sound pads. I'm not convinced that the additional features take the CTK series to new heights, exactly, but the pitch wheel and additional effects are welcome. I suspect that an on‑board sequencer will not be a key feature for most SOS readers, so the offer of a 6‑track version on the CTK‑750 may be neither here nor there.


  • Outrageous amount of fun for the money.
  • 16‑part multitimbral.
  • GM tones.


  • No MIDI Out on some features.
  • Poor quality effects.


Although technically a home keyboard, the CTK‑650 sports a number of features that allow it to compete with more 'credible' synths, at a fraction of the price, which makes it a cheap but highly useful addition to a setup. Tremendous fun.