With myriad cheap sampling keyboards poised to assault the musical instrument world, do we need another upmarket, monophonic sampler? A Swiss company called MDB think we do.

Specialised gear for specialised tasks — a principle the MDB Window Recorder illustrates rather well. It's clearly priced for the professional market, but that's inevitable when we're dealing with recording fidelity on a par with that of Compact Disc.

Still, you might reasonably argue that, with the imminent arrival of a plethora of low-cost, polyphonic sampling keyboards from the Japanese, the MDB will have its work cut out trying to compete. To an extent that's true, but don't forget that in the recording studio, high-quality monophonic sampling still has a great many applications, from reproducing instrumental sounds to spooling in whole vocal choruses — given sufficient sample time.

And rather than turning an AMS or some other upmarket digital delay to long-duration sampling and playback techniques, the Swiss manufacturers behind the Window Recorder suggest that you buy one of their units for half the price, and take advantage of its more extensive sampling facilities. An AMS unit capable of six seconds of sampling costs around five grand, while at its launch, the MDB offered six seconds for just £2750. The original unit could be expanded to give 24-second sampling, while the mass-production 12-second variant (which now costs £2995) can be expanded to give up to 48 seconds of sampling.

And the sampling quality? Sixteen-bit linear, exactly the same as Compact disc. In fact, you can sample a CD into the Window Recorder and be quite unable to tell the difference on playback. I know, I've done it.

The 'Window' bit of the name is a horizontal LED ladder on the front of the 1U, 19" mounting machine, which steps along as a sample is played or recorded to show you exactly which point in the sample you've reached. This is invaluable for precise editing, as we'll see later.

The most important controls on the MDB are the black 'window end' buttons. These allow you to work from either end of the sample, so that pushing Play six times in quick succession in edit mode gets you up to normal speed, forwards or backwards, while lower multiples take you down to very low speeds and allow you to edit sounds to a resolution of 22 microseconds — which isn't very long, I can tell you.

The window buttons then allow you to define new start and end points for the sample, simply by hitting them while you're in edit mode. So, tailoring sounds to your exact specification is dead easy; if your intended sample happens to be in the middle of a piece, it doesn't matter, because you don't have to get anywhere near it on your first sampling attempt.

If your intended sample is at the start of a piece, the MDB allows you to capture it with an Auto Trigger facility on the audio input. The input takes the form of a suitably 'professional' XLR jack, and the trigger level from Ready mode is around -3 on the LED input scale. The input has a High/Low impedance switch adjacent to it for level matching, and as we've just mentioned, the LED window begins to step along as soon as the sampling function starts.

It's also possible to overdub sounds on top of one another. Instead of hitting Record you simply hit Overdub, and the new sound is added without wiping the old one. You can repeat this process many times (as many as 20 or 30 times, claim MDB) and thus come up with extremely complex layered samples, though this inevitably involves a slight drop in recording quality for each overdub you make. The only problem with this particular layering function is that if you hit Overdub accidentally while there's no sound being input, your original sample becomes slightly degraded automatically.

What can you do with your sample once it's in captivity? Well, first you can tune it using the right-hand Tune control, which gives a range of one octave up or down. Then you can trigger the sample with a pulse applied to a rear panel socket, and control its pitch via a one-volt-per-octave CV input. This means that, like the keyboard-modified AMS, the Window Recorder can be controlled from a cheap one-volt-per-octave monophonic synth like the Roland SH101, and you can then play tunes with your sample.

Either a +5V or -5V gate will do to trigger the sample; the +5V pulse is re-transmitted at the start of the sample to pass on to other pieces of equipment such as additional samplers or synths. Another pulse appears at an adjacent socket at the end of the sample to silence any peripheral equipment if necessary; presumably this is aimed at ARP synths and similar 'problem' instruments.

More interestingly, the Window Recorder boasts a MIDI In socket which, like the CV function, gives two octaves of monophonic control over the sample currently held in memory. Velocity information is recognised and responded to by the Swiss machine's software, so a DX7, or a sequencer programmed from another dynamic keyboard such as a Roland JX8P or Korg DW8000, can produce dynamically varied sample response. These techniques will be familiar to many from the cheaper, polyphonic Akai S612 Sampler, but aren't yet available on the more expensive AMS delay.

The Window Recorder's rear panel also features a computer interface for a dedicated disk drive to save samples; and yes, the MDB will 'forget' the contents of its memory on power-off unless you save to disk. Price for the disk drive, incidentally, is yet to be announced.

Although the Window Recorder can't act as a digital delay, it does have a Hold Mode which allows you to repeat a sound endlessly (and that sound can be a whole chorus of a song if you want it to be) and the ability to play sounds backwards. And the window isn't just to show you whereabouts you are in a sound; it can also be used to help edit out and replace small sections of a sample, a process that can extend to individual words, phrases or notes.

All in all, this is an exceptionally advanced facility that should offer plenty of scope to even the most active imagination. You can drop in to Record mode at any point in a sample and drop out again when you've replaced your duff phrase or note, and if you've played along carefully, you can't hear the join.

Personally, I reckon the Window Recorder will find particular favour in the field of advertising jingles. Since these are usually about 28 seconds long, you could easily stick a whole jingle into an expanded unit and prepare 10-, 15- and 20-second versions simply by editing or overdubbing the sample. The 12-second to 48-second sampling expansion was originally expected to come in for around £600; bear in mind that if there are any six-second models still around, they can't be expanded past 12 seconds.

Does the Window Recorder represent good value for money? Well, if it weren't for the fact that there's nothing else quite like it on the market at the moment, the MDB would look pretty poor return for your greenbacks. But the fact is that the Akai sampler is of much lower quality (although polyphonic), and the AMS needs a lot of modification and mucking about before it's transformed from a digital delay into a controllable sampler.

One minus point that is annoying is the fact that you'll have to spend more money on a disk drive if you want to save your carefully-sampled MDB sounds. Some AMS users save sounds on tape, while many more would be offended by the very idea of using the same sound twice, and so aren't bothered either way.

But the Akai certainly experienced a surge in popularity once its disk drive became available, and though the two units are poles apart in terms of design philosophy, the principle's the same: how much time are you prepared to spend on a sound if you know that it's lost forever once the power goes off?

That aside, the MDB performs superbly. As a first entry into the musical equipment market (though I vaguely recall mention of an MDB Polysequencer a few years back — was it the same company?), it's a wonderful, thoroughly laudable achievement. The bottom line is sampling quality, and on that basis alone, the MDB has no competition.

It is a specialised instrument, though, and you'd have to be reasonably well-off to invest so much in a unit that offers monophonic sampling and nothing else. If you'd be happier with something polyphonic, go for the Akai S612 and put up with the quality loss safe in the knowledge that your wallet is no longer a redundant item. If you want MIDI-controlled monophonic sampling for everyday use, go for a Korg SDD2000 sampling delay, and spend the money you've saved on instruments to sample into it.

But if you want to be able to sample 48 seconds of music, take out two notes, turn it backwards, overdub it twice and still have the quality of a Compact Disc, you need a Window Recorder.