Where a human drummer rarely chooses to use more than one snare or bass drum, most beatboxes are well equipped to handle multiple instruments. And with this month's on the beat, so are you.

THOUGH NOT BOUND by any stylistic considerations, this month's patterns come with the benefit of a unifying theme insofar as each of them features either dual snare drum and/or dual bass drum parts. If you've never tried doubling up your snare or bass drum voices in any of your programming activities, you could be forgiven for thinking this seems a somewhat uninspired theme on which to base an article. But, as I hope to demonstrate with the six patterns presented this month, this is anything but the case.

Providing voices are chosen to complement each other and not overlap too much (either in respect of time or pitch), it is possible to create some richly textured patterns which, for power and intricacy, really can show the beatbox in the best possible light. The reason for this is quite straightforward: under normal circumstances both bass and snare drum are fully committed to maintaining the overall structure of a pattern and providing the beat on which the rest of the music is built. Only when a second drum is added do we gain the necessary leeway to start experimenting with these instruments and taking them outside their more customary timekeeping role.

Of course, there's never been anything to stop you keeping time with any of the other drums available to you - using the bass and snare drum simply as a means of embellishment. But having experimented extensively in this area, I have to conclude that our perception of the bass and snare as instruments which lock together to form the fundamental time-keeping elements of a rhythm is now so deeply ingrained that it's quite impossible to drop them altogether from this role and substitute other instruments. Far better, I've found, to make use of the multiple voices available on all machines these days and simply slot in another snare or bass drum alongside the existing one.

In some cases it is possible to use dual bass drums and dual snare drums in the same pattern - you'll find a couple of examples in this month's patterns. I have found there are few rhythms which cannot be enlivened by the addition of one extra instrument at the very least, even if this only involves a straightforward alternation of voices playing the same part - the substitution of a longer, heavier snare drum beat every fourth bar, for example.

In the rhythms presented here, you'll find the idea being taken much further and in some cases forming the very basis of a pattern. As a general rule, the more complex, intricate snare or bass drum parts tend to be better served by shorter, drier voices. Heavy, more ambient sounds should, generally speaking, be reserved for the less frequent notes used for accenting and embellishments. Of course, this isn't carved in stone, and most modern machines make it quite easy to substitute voices, so there's no excuse for not experimenting.

Pattern 1 highlights the use of a second snare drum part to fill in and embellish the spaces left between the second and fourth snare beats of a fairly conventional dance/pop pattern. The main problem when writing a snare part to perform this function is avoiding the feel of cadence entering a pattern at a point where it's not required. Again, because we're so used to hearing snare drum rolls and fills occurring at the end of a rhythmic phrase, programming them to occur earlier in the pattern can give the effect of o bringing it to a premature close. The programming of snare drum 2 in Pattern 1 avoids this by linking it with the more predictable beats of snare drum 1. This provides a continous flow to the pattern which works well.

Like most of this month's patterns, there's a fairly hefty instrument complement which can be thinned out if you wish - though I'd recommend you enter all the parts first and then decide what to leave out. Programming should present no real problems; just make sure you keep the level of the snare 2 grace note on beat three of bar two well below that of the lowest dynamic level of the rest of the part.

A somewhat simpler pattern, Pattern 2 has a decided swing to it thanks to the triplet programming, but this is offset to a certain extent by a ride bell part programmed in straight 4/4. As you will hear, the juxtaposing of the ride and hi-hat timings provides an interesting rhythmic contrast which gives the pattern a very distinctive feel but which opens it up to a potentially wider range of applications than would a straightforward triplet rhythm.

Rather than add a second bass drum part, my intention in this pattern was to show what could be done by splitting the existing part into two and assigning a different bass drum to each. The effect is to add considerable rhythmic interest to what otherwise would be a fairly run-of-the-mill bass drum line. It's a useful trick to remember when you are bound by an existing song structure to a particular rhythm, but are committed to coming up with something a touch more satisfying.

Even more distinctive is Pattern 3, which derives most of its interest from the repeating rhythmic figure formed by the two tom voices, the bass drum and the two contrasting snare parts. Here, the heavier of the two snare voices should be assigned to snare one, but because neither part is particularly complex, you should find you have plenty of scope for experimentation. This is a fairly fast pattern - it won't hang together properly below about 120bpm - but despite this (and the fact that there are 12 instruments to program), it still manages to create enough space for itself and should prove readily adaptable.

My love of Latin rhythm rears its head again in Pattern 4, adapted from a Brazilian baion (or baiao) - which is one of the oldest rhythms indigenous to that part of the world. Stripped of such exotic instruments as the reco-reco and pandeiro, the pattern is probably unrecognisable to inhabitants of the north-eastern part of Brazil from whence it came, but I'm sure even they would appreciate its immediacy and wonderfully fluid feel.

The only instrument which may prove a problem is the triangle, as few machines seem to include them in their lineups, but this can be readily substituted with any bell-like instrument providing the pitch is kept fairly high. The two snare parts, because they're not involved in any timekeeping role and are both quite simple, may be assigned to any suitable voices (long or short) providing they fit in with the overall feel of the patterns as instruments in all Latin rhythms must.

Whereas Pattern 4 stands up on its own, Pattern 5 sounds best when placed in context with a suitable bassline within an appropriate piece of music. The reason for this is that a number of the instruments are programmed "serially". That is, they occur one after another within each bar of the rhythm. This produces something of a "clockwork" effect, which doesn't sound too impressive on its own, but which works extremely well when other rhythmic and melodic instruments are added. Listening to the pattern, I had no problem coming up with half-a-dozen basslines off the top of my head - all of which sounded pretty damn good. That said, I'm not entirely sure why this should be, other than the fact that space is created within the pattern quite differently to the way it would be in a more conventional rhythm. But whatever the process involved, I'd certainly recommend it to your attention as worthy of further experimentation.

Finally, this month, we get heavy. With no less than three bass drum parts, two snares and three tom-toms, Pattern 6 is designed to hit you between the eyes and keep on going. This is thrash beatbox - uncompromising and clearly limited in its application, but great fun and certainly worth the programming should you find yourself in need of a really heavy program. It would be difficult, if not impossible, to prescribe suitable voices for each of the bass drum parts, you'll simply have to program them and then swap and change the sounds until you get the required flow of the three drums playing in concert. And given the power generated by these three instruments, it would probably make sense to program them first and then add the other instruments - choosing voices which will be heard above the machine gun-like impact of the low-end instruments.