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Casio SK2100

Portable Sampling Keyboard

You want a synthesiser, a drum machine, a sequencer and a sampler, but you've got less than £500 to spend? Home-keyboard buyers are currently being offered just such a package, as Dan Goldstein discovers.

Take the ingredients of today's MIDI music system, put them in one instrument, and you've got today's portable keyboard. Does its appeal stretch beyond the home?

IF YOU WERE asked to name the main ingredients for a small, modern MIDI-based music composition system, what would your reply consist of? A synthesiser (maybe two, maybe more). A sampler. A multitrack sequencer, whether of the dedicated or computer-based kind. And a drum machine, with the option of a few pads to play it from. Link that little package of goodies to some recording equipment, and you've got yourself the archetypal small electronic studio of the late 1980s.

But there is an alternative. One that puts all the non-recording ingredients mentioned above into a small box, is easier to get to learn and use than any of them, and is also cheaper than any of them are likely to be.

Ladies and gentlemen, I give you the Casio SK2100 - flagship of the company's "SK" range of instruments (keyboards that are aimed at the home market, but which feature sampling as a major selling point), and by any standard a very tidy piece of technological packaging indeed.

It's a sampler, obviously. Actually, it's an eight-bit polyphonic sampler with a sampling rate fixed at 10.113kHz, and various editing functions - but we're not at the detailed spec stage of this review yet. It's also a synthesiser, with a 49-key splittable keyboard, 12 preset sounds for the upper section, 10 for the lower, and a one-finger chord option to make playing easier for the novice. And it's a drum machine, with seven percussion sounds, 20 preset patterns (all with their own fill-ins), and provision for programming your own patterns in real time. And it's a sequencer, with capacity to store two separate "channels" of information: the first can hold 2000 notes, while the second can hold 1000, plus a total of 159 chord changes.

There's even an amplifier, twin speakers (the SK2100 does everything in stereo), and a microphone for sampling - so that, in Casio's own words, your keyboard is "built to boogie, whenever and wherever you are".


IT'S A PRE-REQUISITE for an instrument like this that the options it offers, no matter how sophisticated, must be quickly and easily accessible. Amateur musicians, dabbling at a keyboard in their living-rooms because there is nothing special on television (yet), are likely to be even less patient and diligent than their pro and semi-pro counterparts, so things must happen fast on the SK2100 if the people most likely to gain from using it are not to lose interest.

Thankfully, things happen very fast indeed. Selecting a preset synth sound involves pressing only a single button. Sampling involves pressing two.

Actually, there are quite a number of buttons on the SK2100's front panel, which on the one hand makes the first encounter perplexing, but on the other hand means that very few switches are called upon to perform more than one function. For weary programmers disillusioned with the multi-function, multi-layered parameter access systems used by many "pro" hi-tech instruments, this panel is a sight for sore eyes.

From the left, we begin with the power switch, which continues the Casio tradition of incorporating an automatic cut-off circuit to save on battery wear when the keyboard is not being used; leave the SK2100 alone for a little over five minutes, and it switches itself off - though your rhythm patterns, your sequences, and (crucially) your samples remain intact during the procedure.

Next come four slider controls for adjusting the relative levels of the SK's bass, chord, rhythm, and sample sections, plus a fifth for varying the overall output level. If you want to hear how your auto-chords and arpeggios are coming along without the interference of the Casio's drum sounds, all you do is steer the relevant slider down to zero.

A small but critical assortment of switches follows - small because the switches are neatly and economically arranged, critical because their position dictates which "mode" the SK2100 is in. For it's here that you select whether you want to start up the drum box, adjust its tempo, or bring in one of its fill-ins; and whether you want to split the keyboard, and then play it manually or call upon Casio's auto-chord system for assistance.

Next come four "pads" (really little more than big, non-dynamically sensitive plastic switches) which you use to trigger samples manually in time with the rhythm pattern - or at whichever moment seems appropriate. You can also use them as a means of inserting and deleting drum voices to/from your own rhythm patterns in real time, if you don't fancy playing those voices from the lower section of the SK2100's keyboard.

The biggest and most complex array of switches comes next, well away towards the top right of the instrument. Essentially, these buttons are what you use to select whether you're playing synthesised or sampled voices from the Casio's keyboard, which rhythm pattern the drum machine is playing, and whether you wish to start making use of a number of auxiliary operations like sampling.

"Things happen very fast indeed. Selecting a synth sound involves pressing only a single button; sampling involves pressing two."

Finally, we come to an input level control for sampling (this actually raises or lowers the threshold of the Casio's auto-trigger system to match the level of the signal you're sampling, and is allied to a five-LED ladder for level indication), and a sweet little microphone that springs out of the instrument's case on a looped cord - though I ought to point out that this is one of the worst microphones I've ever used for anything.

As I've intimated, there's a speaker at either end of the SK2100's keyboard, though a pair of output jacks on the rear panel allow you to use external amplification - the results of this are certainly worthwhile. Other rear-panel connections are few and far between: just a headphone socket, a connection for a volume footpedal (optional), the plug for the mains adaptor (9V DC, and also optional), and two jack inputs for microphone and line signals to go to the sampler. Then there's a master tune control (50 cents either way) and that's that.


THE DOCUMENTATION MAKES no mention of the manner in which the SK2100 generates its synthesised sounds. But after listening to them all thoroughly, I'd be willing to bet that digital technology plays a large part in their creation; there's brilliant, sparkling clarity, great precision, and... the inevitable quantisation noise.

Like most digital systems (for in truth, this is something that can be said for even the most sophisticated sampling systems available), this one excels at reproducing acoustic timbres that have a percussive attack and a comparatively short decay time, but falters when it comes to longer, sustained sounds because it is simply not "clever" enough to recapture the sort of sonic movement that goes on when, say, a string section is in full, sustaining flow.

Thus the best of the SK2100's sounds are the likes of the vibraphone (richly resonant and, well, vibrant) and the celesta (a truly glittering occasion), while the piano is also usable if a little on the dull side. The solo violin is also nice, if not especially violin-like - the basic envelope characteristics are there, but some of the timbral details are not. With the brass and organ sounds, things start to stray dangerously into Toytown territory, and the less said about the unimaginative "Synth Sound" and "Synth Ensemble" programs, the better.

The SK2100's drum voices are PCM-sampled, but are nothing like as bright as those of some other, similar machines - including some of Casio's own. The bass drum is little more than a soft, dull thud, the snare an insistent crackle, the cymbals and hi-hats weak splashes, and the handclaps a tinny, half-hearted crunch.

Unpromising though they may be in isolation, however, these voices contrive to sound like a pretty credible little ensemble when played together as part of the SK2100's preset rhythm patterns. These patterns are modern (less waltz, more rock), interesting and well thought-out, and it's while playing along with them that you realise this is what modern rock and dancefloor rhythms are all about. Steady, metronomic pulses, Filthy sounds, and neat fills that alter the direction of the pattern subtly without shoving the all-important groove off the rails.

The other main ingredient of today's rhythm is, of course, the spice we know as samples. Those naggingly infectious, ultra low-quality vocal snippets, orchestra hits and reversed drum sounds that distinguish today's dancefloor workout from those of the late 70s or early '80s.

Well, the Casio can do those, too. In fact, it comes with four such samples onboard, safely protected from corruption in ROM so you'll never be free of them. There's a piano with a truly excellent "plink" to it, a vibraphone that's a pleasing if gritty contrast with the Casio's synthesised version, a slightly muffled conga, and a French horn with an identity crisis - though I'm not sure what it actually thinks it is at all.


IF YOU WANT to sample your own sounds, you can choose whether you want to use all four of the RAM locations, which'll give four samples each 0.81 seconds in length, or whether you want to merge the locations together to form two bigger ones, each 1.62 seconds long.

"There's no tricky LCD of values or monitor-full of waveforms - just five drawings of different envelope shapes matched to keys."

Whichever you decide on, however, the sampling rate remains the same at 10.113kHz. This is a pity, since I'd have thought an option to double the sample rate to give two higher-quality, 0.81-second samples would have been handy to have. There surely comes a time - even for domestic keyboard dabblers - when sound quality matters more than sound variety, but perhaps Casio's engineers reckoned an additional "rate" parameter would confuse people more than it would help them.

As with any other sampling system, the best way of minimising noise problems with the SK is to sample at as high a level as you can without encountering distortion (so that the playback system doesn't have to impose its noise characteristics on the sample in order for you to hear it), and to use a line input wherever possible (so that microphone noise doesn't have a chance to intrude, either).

I used all three input possibilities (built-in mic, external mic, and line-level) during the test period, and can confirm that the least noisy results - though not necessarily the highest-quality ones - can be obtained using the last option.

Once you've taken your sample, you can play it back polyphonically (maximum three voices) from the SK2100's keyboard, use it as an instrument in a rhythm pattern (preset or user-programmed), and do a number of other things with it. However, since it's not possible to play more than one sample back from the keyboard at any one time, you can't use your four memory locations to record the same instrument at four different pitches. In other words, you can't "multi-sample" with the SK2100. So, depending on the signal you've sampled, the pitch range over which it can be played while remaining realistic can be rather narrow.

Of those "other things" mentioned above, the most interesting fall into the category of sample manipulation, rather than sample performance. You can loop your sample, reverse it, mutate it so that it follows a choice of five different envelope shapes, and transpose it by as much as eight semitones down or seven semitones up.

The reversal and envelope procedures can be particularly rewarding, and they're a cinch to use. There's no tricky LCD of values or monitor-full of waveforms to deal with here - just five drawings of different envelope shapes matched to five of the keys in the lower half of the Casio's keyboard; get into the right mode, press one of the keys, and your sample suddenly has a new envelope imposed upon it.

Looping on the SK2100 is done automatically by internal software, and though this means that it can be accomplished just as quickly as any of the other editing options, it also means that the finished product rarely complies with any legal use of the term "glitch-free".

Sadly, Casio haven't made any provision for users to dump their samples as digital data for retrieval at a later date - even to humble cassette tape. They're retained in memory during power-down, but as soon as you put another sample into a certain location, the sound that previously occupied it is erased. Home-keyboard users may not want sound of the highest quality, graphic editing packages, or velocity-sensitive keyboards, but they sure as hell would like to build up a library of their favourite family samples. Wouldn't you?


YOU MAY HAVE wondered, from the outset, why this magazine was even looking at a keyboard like the SK2100 in the first place. I hope I've made our reasons fairly clear during the course of the review, simply by outlining what the instrument is capable of doing.

First, it represents a sensible choice for the amateur musician who's keen to get into sampling, sequencing, drum programming and so on, but can't hope to afford to do so unless all those things are available within a single package.

Second, it is exactly the sort of instrument that domestic "non-musicians" - people who at the present time do not have any particular ambitions to play modern music, but who may acquire them someday - to let their creativity loose a little bit more than instruments in the £100 league will allow them. Casio have sold over a million of the baby SK1 sampling keyboard, and they know that the SK2100 players of today are the FZ1 programmers of tomorrow.

Third, it makes a fine addition to the arsenal of instruments possessed by pro and semi-pro musicians. It can be a practice keyboard for those last-minute, hotel room panics; it can be a handy tool for songwriters to map out simple arrangements of new material; and it can be a cheap and relatively painless way for, say, accomplished piano players to find out for themselves whether sampling really can be a musically useful technique.

Ultimately, the Casio SK2100 is a toy. But it's also of great educational value, and it has a number of other aspects to its character that give it a broader appeal than most home keyboards could have aspired to a couple of years back. And I, for one, am glad that it's around.

Price £425 including VAT

More from Casio, (Contact Details)

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Steinberg Cosmo

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The Price of Fame

Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - May 1987

Donated & scanned by: Mike Gorman

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Keyboard - Home/Personal > Casio > SK2100

Review by Dan Goldstein

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