Nick Graham tries an Apple, a Broken Bottle and a Microphone? Is this the future of high tech?

In most of their adverts, the Greengate people show a picture of an Apple IIe computer, a keyboard and a microphone placed next to a broken bottle. This implies that, with a microphone plugged into the Apple, the sound of the broken bottle can be sampled and stored in the computer's memory. Once there, the sound can be played on the musical keyboard at any pitch. Simple as that - or is it?

Not quite; because it's not possible for an ordinary micro-computer to understand a signal from a microphone (let alone store it and regurgitate it as sound) without a suitable interface - and this is where Greengate come in. They have designed a slot-in card which, once inside the Apple (slot 5), can convert incoming electrical signals from a transducer into something the computer can understand and remember. In fact the sound can be reproduced at any pitch and in four-note polyphony, thus turning the Apple computer into a versatile sampling instrument. The card which makes all this and more possible is called the DS3 - and that's where I come in, because I bought one myself not three weeks ago! (mad fool! -Ed.)

Since the card would have been useless on its own, I also bought an Apple IIe and two disc drives. I didn't however, buy the musical keyboard which Greengate supply, so my sounds have to be controlled from the QWERTY keyboard. One of their promises was to produce a MIDI interface (another slot-in card) in the near future, and I decided to wait for that so that I could play my sounds from one of my two touch-sensitive MIDI keyboards.

I must admit that since I took delivery I haven't had very much time to explore the full possibilities of the DS3, so this review will be limited to the actual sampling and waveform editing of sound, leaving the extensive sequencing and synchronising capability until a later date. Before I delve into this, however, a brief description of the processes involved in sampling might be useful.

Many of you may stop reading at this point and continue further down the page because you already understand - but it's surprising how many experienced musicians don't know the ins and outs of it. This is amazing, especially as the sampling of real sounds plays such a large part in the music of today. For those interested, please have a look at the diagram, which shows all the links in the chain. (This bears particular information relating to the DS3/Apple system, but in fact this chain is true for sampling devices generally.)

With the assistance of the DS3, the computer can look at and analyse exactly what makes up a sound. As the electrical impulses from the transducer enter the DS3, they are minutely examined. To be precise, they are examined, or 'sampled', every 1/30,000th of a second, and each time the computer stores in its memory all the information about the nature of this very thin 'slice' of electricity. Thus for every second of sound the computer stores 30,000 separate 'slices' - when you want the sound back, what you have to do is command the computer to find this information and piece it back together. As I mentioned earlier, the Greengate system allows this to be done from the typewriter keyboard of the computer, and well as from a normal synth-type keyboard.

There are two ways to sample sounds on the DS3/Apple system. One is to use the threshold mode, which is a gate that opens and starts recording the sample when the sound reaching it is at a high enough level. The threshold (i.e., the level at which the gate opens) is, of course, user adjustable. Alternatively, the threshold mode can be bypassed so that the machine samples everything it 'hears' from the moment the return key is pressed on the computer. This can be very useful when recording an event which you know is going to take place; perhaps that orchestral stab at the end of Beethoven's Fifth, or a snare sound from a David Bowie record! In general, though, the threshold mode will be more used, and although it takes some practice to set the control so that it doesn't either cut the front of the sound (set too high) or trigger from room noise (set too low), I found that taking successful samples with the DS3/Apple system is incredibly easy.

Having successfully recorded a sample, it's now possible to immediately trim the sound. For example, a delay at the beginning or rubbish at the end of the sound can be chopped off, and if this produces the desired effect, then all that remains is to store it on a disc. However, if the trim option can't remove unwanted noises, then this is where the Greengate waveform editing facility comes into its own.

Selecting this option enables the user to display the entire waveform on the monitor screen, and, by means of a games controller (paddles or joystick), to step through it and find any unwanted noises or gaps. Not only can the front and back of the wave be trimmed entirely accurately, but the wave can be literally redrawn to suit your exact requirement I must say that, although it takes a lot of patience to do this, it's a facility which promises to be a very exciting creative tool.

At the moment, the maximum sample time offered is 1.3 seconds at the full bandwidth of 15kHz, but if you are prepared to accept a bandwidth of 7.5 kHz, then the sample time is extended to 2.6 seconds. However, with the addition of extra memory to the Apple, Greengate have promised a sample time of up to 10 second at full bandwidth, and this is to be announced sometime this year. Already software is available for 'looping', which allows sustained sounds to be played, and it's clear that the development of the Greengate sampling system is an ongoing concern.

On the basis of what I've seen so far (sorry; heard so far!), it's clear that in many applications this machine can emulate the performance of much more expensive sampling systems, and if like me, you buy the whole package, you also get a very good home computer. If you already own an Apple, or have access to one, then you can't afford not to have a Greengate DS3 card in it. But one tip - buy a good microphone, because without one good sampling is almost impossible.

RRP £632.50 Inc VAT (basic system inc keyboard), £1840 Inc VAT (system inc keyboard and Apple IIe Computer)

More details on the DS3 system from Greengate Productions, (Contact Details).