Last month's review of the Stepp DG1 guitar ended months of speculation about the instrument's capabilities. Yet we've still only scratched the surface of what is an undeniably complex innovation. Steve Randall, the Stepp's inventor, puts us further in the picture.

Tell us some things that we don't already know about the Stepp.

Well, the starting point is that we wanted all of the controllability of the instrument to be on the guitar, because we felt it was very important that the guitarist controls guitars and not synthesisers. It's also very important not to blind the guitarist with science so, even though there is a membrane panel with lots of terminology which he might not understand at first, there are only three knobs on it - the master control, which takes him through 100 different sounds, a master volume and a master tune.

In a way, the guitarist can ignore anything else. He gets the guitar, turns it on, and there's the sound. By turning the master control you go through from sound number one through to sound number 80, and then into split sounds - which are a different sound on each string, multi-timbral. If he wants, that's all he has to do. The more adventurous guitarist can edit the sounds and then re-record or rewrite them into the instrument. So that's the starting point.

But the challenge of making it expressive or guitar-like is totally different to dealing with a synthesiser. On a synth you basically have a key, which you press down and it turns the circuit on - take your finger off and it turns the circuit off. It's a very easy thing to imitate a piano's type of action, but on a guitar you pluck strings, you mute strings, you bend strings, you slide up, you slide down and you do all sorts of things and sometimes you do these things subconsciously. For a guitar to sound like a guitar, it has to do all those things.

Once you can create those things in software, then you can impersonate a guitar so accurately that the expression of, say, Eric Clapton can be translated into electronics and sound different to Bert Weedon, for instance, and the two will sound different for obvious reasons.

For the instrument to sound like a guitar it must be responsive immediately - you don't want a delay. In our particular case, we have gone for an active neck rather than real vibrating strings. Systems like the Roland have their merits because they almost started it all up but, from where we were standing, we thought the Vox Guitar Organ was nearer in concept than that.

Anything with a vibrating string needs to be translated, first of all, into a language that synthesisers understand. In translating a vibrating string into MIDI or anything else, there has to be a time delay; whether it's looking at it for one cycle, two cycles, half a cycle - it's still a delay. The lower the string, the bigger the delay, and that's just to get "note on" information.

So we steered clear of that and we used active frets, which we call SCI (Semi-conductive Intelligent) frets. It's a one-piece component - not made of metal; it's a special material which detects when a string is touching it, and then knows how far the string has been dragged across it, for bend information. It's constantly analysed by software which, because it sees the string moving, can say "Update pitch by a semitone or an octave, or whatever the program is".

But it needn't be pitch. These are effectively "software" frets. You can bend a string and it can control pulse, width, or the cutoff frequency of the filters, or the waveforms.

The average guitarist probably doesn't even understand that terminology, so can you give it to us in guitaristic language?

Yes. Well, I'm a very average guitarist so there are certain things which I see guitarists doing and I think: "I wish I could do that!"

Bending one string against the other, so you bend one string up to the frequency of the other, is a technique which I find almost impossible on a conventional guitar. If you route the frequency of one bank of oscillators to the frets and you keep the other frequency static, but a bit higher up, you can actually do that on the Stepp automatically. Just bend any string and it will slur the frequency up to the other one.

Another one is that some people might want to have a tone change when they bend a string, rather than a pitch change. So, if I take the cutoff frequency and put that on the frets, you actually get something that's quite cat-like.

So you are bending wah-wah?

Yes, but rather than being a function that goes backwards and forwards automatically, like the Low Frequency Oscillator (LFO) on a synth - a static function, it's a function that's under the fingertip control of the guitarist. It's something that's translating expression.

There's a major difference between the Stepp and any conventional guitar, in that the strings are split in the middle. That is done so that the electronics can tell the difference between your right hand and your left hand, because you do all sorts of things with your right hand, like damp strings and pluck strings, the computer needs to know the difference between each hand. The only way to do it is to split the strings.

That is quite a weird thing at first for people to grasp, because all the tactile references that they're used to - like bending a string and feeling a slight bend in your right hand, or plucking a string and getting a vibration in the left hand - all of those things you use very, very subtly, but you take it for granted. When you pick up the Stepp, you become aware that that tactile reference has been taken away.

You also become aware that bum notes and all sorts of other things come out just as gloriously as the accurate information. So that takes a little bit of getting used to, but apart from that, there really isn't a compromise. The fact that the strings are split in the middle does mean that they are anchored just past the last fret, and bending at the top fret is a bit tighter than normal, but we have a multiplier effect so the resultant bend is bigger than normal. Most people will find it easier to bend in the middle of the Stepp, rather than at the top. In fairness, this is an instrument that is aimed at guitarists, because the instrument is in a guitar format, but it's got to be treated as a new instrument.

The electric guitar was treated as a new instrument when that was introduced. In fact, when it first came out, people said it was a thing that wouldn't work properly; it fed back, it distorted. It took people a long time to know how to treat it and it's only when you play rock music on an electric guitar that it becomes a new instrument - electric guitars shouldn't really be used for finger-picking classical music.

So every guitar has got its purpose, and I don't think an electronic guitar is an instrument that should be picked up and treated exactly like an electric guitar.

The other half of it is that synthesiser players are very used to playing the sounds. If you've got a very slow string sound, you don't start stabbing away at it percussively, because nothing will happen. You will never get past the attack curve. When the synth first came out, the only people that understood how to play it were piano players, because that was the format. A lot of people said: "It doesn't feel like a piano, so I won't play it", and it took many years before things like Switched on Bach and Popcorn started making people so curious about the sounds that they didn't really care about the tactile differences.

I think that's going to happen with electronic guitars. The conservative guitarist will be afraid of it, but almost for the sake of being afraid of it. It's not like a Gibson, it's not like a Strat, and I never want to be in a position where I'm convincing somebody to buy it because I don't think of myself as a salesman. I would rather think of myself as somebody that's spreading the gospel about electronic guitars. If people are interested, they will do different things. I've had a number of cases now where guitarists have come back to me and discovered things about the Stepp and I've learned things from them.

I remember Bill Aitken saying much the same thing about the SynthAxe - that every single person played it in a totally different way and got a different thing out of it. Do you find that?

I find there's a period of about five minutes where I can tell whether a guitarist is going to be an electronic guitarist. And I would say that 99% of it is nothing to do with his hands - it's to do with his brain. It's nothing to do with whether you're a brilliant guitarist or not. It's purely mental attitude.

Again, it happened with Simmons drums, which have the facility of making an average drummer sound brilliant. If you are a brilliant drummer, you could use that technology to sound impossibly brilliant, or you might find it so restrictive that you could be made to look like an idiot.

Because the guitar is such a tactile instrument, everything about it is sweat, really. On a synth you can pick it up and get something straight away, which means that it's a very disposable instrument. Kids get bought little synths for Christmas; they tinker away at them and most of them end up on top of cupboards and are never used again. The thing about guitars is you have to have your fingers in a state where they're hurt, almost bleeding, and if you get to that stage you're a guitarist for life. The kid that's been bought a little Spanish guitar to learn on, one day will want a Gibson or a Fender, and that really hasn't changed. One of my ambitions is to have a situation where someone can go into their local chemist and buy a Casio electronic guitar. He presses a little button and it plays a metronome type of drum and he learns E, A and D. And one day wants to buy a Stepp, because that's the grandaddy of the electronic guitar.

I don't know how far we are from that, but judging by what's happened with synths and drums, it may take five years. We have to educate the people first.

I'd love to do a bass guitar version of the Stepp. That's a totally different challenge. Bass guitars are being virtually replaced by synthesisers now, and a lot of people have asked me about a bass version. It's very easy to say no, it's too difficult, but there's got to be a market for that sort 6f thing.

But you can tune the Stepp into a bass-guitar register, can't you?

Yes, this has got an eight-octave range, but it's the scale and it's the fact that you'd like to be able to slap onto it as well, and get a totally different envelope. I think it would be nice to dedicate an instrument to a bass. I'm not saying we're doing it, because I think the task is almost as mammoth as making the Stepp in the first place...

Another aspect of why playing the guitar is different from playing synthesisers, is that people mute strings all the time - either damping a string to turn it off or plucking and muting the string at the same time, which gives you a totally different, shorter envelope. If you muted and plucked a violin string sound, you'd want to get it "pizzicato", and that's something you can't do on a synthesiser. But you can do it on the Stepp. The muting envelope is a totally separate portion of the envelope. There are two independent envelopes that can be routed to different parts of the synthesiser so, in English, that means you can have a particular "shape" of the sound which is overridden with a different shape when you mute the strings and pluck them.

On a guitar, touching a string is sometimes an intentional piece of musical information. You might want to stop that string from vibrating and, in reality, you would stop it from vibrating. In a software-based guitar you are telling the software that if I pluck that string I don't want it to vibrate, I want it to go "flupp". So, I'm touching the string, you can't hear anything but the software knows I'm touching it. It's monitoring for being touched.

How does the Stepp detect that you are touching the strings; is it resistive?

It's actually capacitive. Capacitance is monitored all the time. I think you can do it with resistance as well, in fact I'm not even certain that we don't do it that way, but I think it's capacitance.

On the right-hand side we use sensors to pick up the vibrating string, but we don't need to see a vibration as such; we need to see just the first impact.

Say you rely on a vibration for your information, which is what the Roland does. Let's imagine you've got a sound - a long orchestral string sound. Sometimes the sound will dominate your thoughts, you'll pluck a note and the sound's a long, beautiful, swirling sound and you're not listening to the string, you're listening to the sound. If the string stops vibrating, and suddenly shuts off this orchestral piece, it can be a very embarrassing moment. So Roland get round it by having a hold pedal. But then the guitarist could become like an organ player with lots of pedals on the floor.

The way a guitarist deals with sustain is that he knows when he plucks a string that it's got a particular sustain; he hits it harder and it will go on a bit longer, and on the Stepp you can program that. If you want the string to take five seconds to decay, or 30, you can program that. You can also program the sustain so you can hit it and it'll go on forever. The way of overriding that is just to damp the string with your right hand, which is what you would do on a conventional guitar.

Supposing you want to change chords but still have the notes ringing as you take your hand off?

You can only do things that are guitar-like. The best way of thinking about this would be to suppose you've got a conventional electric guitar and a fuzzbox which will give you infinite sustain; can you play a chord, get the chord to sustain forever? Once you start sliding around, you carry on sustaining because you haven't damped the string. If I take my fingers off very slowly, I've actually damped it. If I take my fingers off very quickly, I've pulled off to an open string, which will actually happen on a guitar. Now, people that know a lot about synthesisers can actually see something there that the guitarist doesn't necessarily know about yet - it's sort of the next question. "Supposing you play a chord and you take your fingers off and you want the chord to continue?" Well, that's an interesting thing, but it's something that's impossible on a guitar. It's not impossible on an electronic guitar because, once you've got the information, you can decide what to do with it. At the moment we choose not to do anything with it - almost out of arrogance - because if guitarists pick it up and it's in a sustain mode, or a hold mode, it's just another parameter they have to come to grips with.

We're introducing a pedal which will be called the Universal MIDI Station, and it will have the facility to remember the last chord and just sustain it 'til you release the pedal, a bit like the Roland, and SynthAxe, almost.

The SynthAxe does it by turning the left-hand damping off...

The more adventurous guitarists that have played this have virtually dictated what the pedal should and shouldn't do. Because we can now take any of the parameters from our membrane and put them onto the floor, you're changing things that will be impossible on a synth or on a guitar, so why not utilise this pedal for more than just hold, for all sorts of things? It will be an automatic - no pun - stepping pedal so you can step through the programs in any order, which is really useful for live work. Again, there are pedals available at the moment that can do that...

...like the SynthAxe?

...but we want ours to do lots of different things. The Stepp really wasn't designed specifically for live work or studio work, but it really is more of a studio instrument at the moment - in the same way that a Fairlight is more of a studio instrument. I think in a live situation the guitarist will make demands tn it that the studio musician might not. Even getting a cable that's long enough for a 60-foot stage ...things like that are not just a question of making a 60-foot cable, you have to deal with digital information.

Tell us about the vibrato bar.

Well, not only are the frets software controlled, but also the bar and the strum strings. You have the facility now of having a wah-wah on the bar, or bowing volume - it's actually very nice to have a string sound and be bowing it on the bar. And it's much easier to use the bar as a volume control than using a volume knob. Again, as an average guitarist I found it very difficult to get my little finger around the knob and bow. Some guitarists have got an incredible technique of doing that, and they might find that the bar is harder than what they've developed over 15 years of practice. But for the average guitarist, it's much easier to use the bar.

You can also do things on the strum strings. If you route, say, the balance of the oscillator banks onto the strum strings, they can have really lifelike feedback. You can tune the two oscillators so that one's a harmonic of the other and the harder you hit, the more you bring in the other oscillator - which actually sounds like you're picking up a harmonic.

You find that if your ear hears the LFO more than a couple of times, it realises that it's not natural. But it's very difficult on a track to hear that as being a synthesiser - it would sound like a guitar feeding back. This is where it gets quite interesting, I think, because that's an effect that's enhancing the guitar-type technique, or enhancing the guitar-type sound, electronically. Which means that either an average guitarist can sound more interesting, or an interesting guitarist can sound almost impossible. Or either guitarist can have that effect electronically controlled, say, with a sequencer. He can have the screeching guitar solo feeding back via a sequencer, which is all very bizarre. Your performance could be captured in MIDI, and then afterwards the producer could decide what he wants to do with the solo, whether he actually likes every single note, or whether he wants to change the sound...

Like the SynthAxe, you have a left-hand trigger switch...

The keyboard mode switch or left-hand trigger is something which allows a string to be instantly triggered the moment it touches a fret, which is useful either for very fast solo things - you don't have to strum it and you can slide all over the place and get incredibly fast licks - or for two-handed play.

We've actually discovered that you spend a few milliseconds getting the fingers into position when you shape a chord, and if the sound is too percussive and too short, you can actually hear the fingers going down in series. This whole area of the Stepp requires a technique that really opens it up, but if you just approached it from scratch and thought you could get something straight away out of it, you'd be wrong.

For me that's quite an interesting area, because I'm using two hands, which I've never been able to do. It's never occurred to me to do that and I'm now doing things that to a certain extent might not be that interesting to a synthesiser player, even though it might be pretty difficult to do on a conventional synth. I'm doing things that are very unguitar-like, and that's one of the areas that I think people must grow to appreciate, because you can't just pick it up and suddenly start a new method of playing an instrument.

What it does give you is the format. You recognise six strings, you recognise the 12th fret, you know exactly where you are, so that's the starting point. Then you need to lock yourself away in your bedroom for about a month and develop whatever you want to develop - how best to maximise this new facility of playing. In some cases people won't, but in other cases people will do things that have until now been impossible on any musical instrument. I think that's where it's gonna get exciting.

Guitarists are going to be interested in what you can do as regards playability. You've given it a very low action, I see.

We're doing work all the time on the guitar so that action can be adjustable or frets can be a certain height. I mean, it's very difficult to say: "This is the standard guitar that's going to please everybody".

As far as the playability is concerned, from the first fret up to the 15th, the scale is exactly the same as a Gibson Les Paul. From the 15th onwards the frets have been evened out so that they're a bit easier to play. The string spacing is very similar to a Fender.

We use the same gauge strings, which are especially made pure stainless steel. All the guitar strings on the market which are called stainless steel aren't really: they're stainless steel plated and they will tarnish eventually.

So again, as far as playability is concerned, the guitarist has to come to terms with playing a single gauge string. As of the end of January we are offering four different gauges, but they won't be wound strings. They'll range from 14 thou to 20 thou.

Do you have the tension of the neck strings set to anything specific?

They don't need to be tuned, the tension is purely a preference of the guitarist. You'll find there's an Allen key that's housed in the headstock, which adjusts the tension. If you wanted to, you could have ridiculously low action with very, very floppy strings, so that it's incredibly fast. Or you could make the strings extremely taut, so that it's very tight. Most people actually adjust the tension so that it's more or less what their real guitars feel like. You can adjust the tension on the strum strings in the same way, and most people just want them fairly tight.

We've had a sort of controlled experiment where we changed things physically that have no effect at all electronically, but guitarists still perceive there to be an effect. We've also had situations where people that really don't understand the technology have been astounded that there are no delays, that they play it and there are no delays. And yet they still think that the bass strings are slower than the top strings, no matter what you tell them.

Which parameters can you assign to the control knob?

Well, not every single parameter is assignable. Obviously you can tune the instrument to whatever frequency you want, from an E up to three Es higher, or whatever. Or, press "Tune" again, and tune just the sixth string, press it again and tune the fifth. You could change the volume of each string in the same way. It's just a patch, so that patch 19 might be tuned to C, whereas patch 20 might be a standard E. You can punch in a chord and that will be memorised as a chord.

So, if you punch it in to patch 28 for instance, every time you call 28 up, it will be in that tuning?

Yes, and anything that requires updating, resonance for instance, can be changed by using the master controls.

There are three digital displays. One tells you which program you are on, one tells you the range of the parameter that's been assigned - to, say, the performance bar or the strum strings - and the bottom display gives you the value of any parameter you are changing. When you first go into edit mode, you have an opening menu which flashes at you, and anything that's flashing can be edited. In that state the master control is doing nothing - it hasn't been assigned to anything. If I press say, Cutoff, everything stops flashing apart from something that can still be edited to cut off. But cutoff stays on, and the display shows you the value for cutoff and the control now adjusts the value of cutoff.

Apparently, by routing 13 modulation destinations to six modulation sources in any combination, there are something like six billion permutations.

Is the guitarist still going to be confused by these technicalities?

I steered clear of getting involved with too many technical traps because was brought up on synthesisers that you could turn a million controls on and accidentally find sounds, and nowadays, that's really not the norm.

For instance, bend is something that guitarists know about. Just press Bend and you can change the amount of pitch-bend on the instrument on that patch. Before we named that function "bend", you had to "assign oscillator frequency to the frets" - so you'd already lost guitarists...

It's designed so that from the start, all you need to do is turn one knob for different sounds. If you just press one button, you can tinker around and change things and you're not going to do any damage, because it's a two-handed operation to erase any sound. You have to know what you're doing to erase the sound and put a new one in.

Does it take guitarists very long to get to know how to operate the Stepp?

I think it takes longer to feel comfortable with a brand new instrument, than to go forward once you're comfortable with it. From personal experience over a relatively short period of time, I would say that people need to sit down for a couple of hours before they even start breathing properly - so, once they've got over those two hours, then it's very exciting.

You've given MIDI a secondary role but admitted it exists, and given your Stepp player the facility to use it...

What we've said is that MIDI is very important. It's on every instrument, but it's not the sole reason that instrument exists. MIDI takes the same priority on Stepp as it would do on a DX7; you don't buy the DX7 because it's MIDI, you buy it because of the sounds. So the MIDI facility on the Stepp needn't be very complex. But I think that most guitarists that take up the Stepp are looking at the Stepp before they are looking at MIDI.

On the MIDI side, you can plug it into a DX7, strum it and away you go, or plug it into a sequencer and record your guitar and, because we've got MIDI In, you could do something like plug a keyboard into the Stepp and have the keyboard controlling the Stepp. You'll be defeating all the guitar expression, because you are controlling it from a keyboard rather than strings - but you can still do that.