It may be worth acknowledging at least some of the electronic drum kits and accessories which we've purposely excluded from this review so far. Many of them have separately available voice modules and trigger inputs which could allow you to play them from a drum machine or sequencer, and some even have elementary built-in sequencers, if only to play basic patterns which help you keep time.

A small number of drum machines proper also have pad inputs, which means that you could play them live or programme them in a slightly more lifelike manner, but any MIDI drum machine can be played from SIMMONS or other pads using the SYCOLOGIC PERCUSSION SIGNAL PROCESSOR or the RMS PROGRAMMABLE PAD INTERFACE (RMS also have a sampled drum sound module coming up). Another useful addition, this time for drum machines which have DIN sync but can't lock up to tape, is the MPC SYNC TRACK, which simply converts the DIN sync pulse to something more suitable for tape recording and re-converts it on the way back, adding the 5V Start/Stop signal needed in the DIN sync design.

Tape sync allows you to change or overdub your drum pattern at a later date, or even run your machine live into the final mix without ever committing it to tape — you'll find it's a great advantage.

On the kit side, Simmons obviously dominate with the old SDS 5, the superb SDS6 drum sequencer with its flashing graphic display, the newer SDS8 and SDS9 and the budget SDS200/400/800 series kits. Great kits, great sounds, and usually compatible with drum machine triggers if you want to add the Simmons sound to your ailing Drumatix, for instance.

Simmons have also made innovations in another growing market — the EPROM blower. Their SDS EPB unit can sample sounds from a mike or line input and record them on chips suitable for the SDS 7, SDS 1 PAD or DIGITAL CLAPTRAP, and of course this increases the power of your sampled kit considerably.

OBERHEIM have a PROMMER, or EPROM blower, coming up to match the re-designed MIDI version of their DX drum machine, and this promises to be highly versatile. Even more powerful is the GREENGATE EPROM BLOWER, part of the DS:3 sampling system based on an Apple computer. The Greengate allows you to sample any sound and blow it onto a chip for the Simmons, Drumtraks, Drumulator or almost any other digital drum machine. PCM system owners are excluded — sorry.

The TED DIGISOUND units hold a single sample which can be triggered from pads or a drum machine, and again there's an EPROM blower in the system, the WINNER. Blank EPROM chips such as the commonly-used 2764 are around four quid in the shops, so blowing your own rather than paying commercial prices can rapidly become economical. If you are changing chips a lot, be sure to invest in ZIF (Zero Insertion Force) sockets — at around £5 each, these fit into the chip sockets of the drum machine and have a lever which allows you to release the sound chip without having to exert any force, and thus avoids eventually snapping its little legs off.

Clavia D-DRUMS are similar to the TED units but give much more control over the sound's parameters. They're an ideal way to add a few sampled sounds to a cheap analogue machine, but unfortunately don't allow the user to sample his own sounds or even blow them onto chips, since the units are loaded with pre-programmed sound cartridges offering between one and four sounds.

Another powerful sampling system is the DYNACORD digital drum kit. The PERCUTER-S is an eight-track drum sound bank, the BIG BRAIN is a 16-track drum sequencer, and the BOOKER is a digital sampling unit. It uses blank sound cartridges which can be set for varying sampling rate, filter factor, time constants and de-emphasis.

Dynacord also market the DIGITAL HIT, a pedal-style unit which contains any one of a score of digital drum sounds. A mike in a real drum triggers the sampled sound, and the original sound can be mixed in at will.

Korg's MR-16 RHYTHM SOUND UNIT is a bank of 19 PCM-sampled sounds which can be played from a MIDI keyboard or sequencer. Sound quality is similar to the DDM110/220 DRUM machines.

MPC's original play-it-by-hand drum unit, THE KIT, is now discontinued (as are its accompanying Clap, Tymp and Synkit), but it's available quite widely second-hand. Its snare and cymbal sounds were very good, its toms less so, but as an inexpensive source of basics to play by hand it's ideal. Its hi hat has a very basic selection of patterns built in to help you keep time.

MPC now have a wide range of drum pads, analogue drum sound modules such as the DSM1, DSM8 and DSM32, and a Commodore-64/Spectrum/ZX81-based drum sequencing package, the PROGRAMMER 8.

TUBBY DRUMS have a few similar products too — their basic system of milking up acoustic drums with miniature mikes on flexible stalks has been expanded with the launch of Tubby Synth, a drum sound module.

One generally popular drum sound module is the clap, which is often omitted from cheaper machines such as the Roland TR606. The machine's tom-tom triggers are perfectly suited to pedal-style clap units though, and these are available from BOSS, from AMDEK (in kit form before the line was discontinued) and from FRONTLINE via Strings And Things. Frontline and Boss also have small drum synth units which can be clipped onto a snare or other drum for disco effects, and many other companies including JHS have marketed similar units under different names, sometimes with a white noise source and sometimes simply with an oscillator. JHS sadly no longer market the old Depeche Mode favourite, the flying saucer shaped PRO-RHYTHM, a drum synth built into a pad unit which could create all manner of white noise, oscillator and ring modulation effects.

On the subject of pad-based units, there are several devices you may find on the second-hand market which are compatible with most drum machine output triggers. The Star Instruments SYNARE was an innovator in the field not often seen in the UK, as was the Pollard SYNDRUM. The Synare 3 with its eight pads was particularly impressive, and if you see any of these units it's worth considering them if only for their visual appeal. MOOG used to market a percussion controller for their MiniMoog, MicroMoog and modular systems, but this didn't create a sound of its own; it was fitted with a Remo head though, and so must have been fairly comfortable to play. Simmons SDS 4's and even earlier models are also about in some quantities — beware of Simmons wrist on these units, as these were the days before nice soft rubber pads were invented.

As far as we know the Pearl SYNCUSSION unit is still being made, although obviously it's outdated by Pearl's new digital drum kit. The Syncussion provides two drum sounds with partly programmed and partly variable oscillator, white noise and ring mod effects, and although it's normally triggered from a pair of pads it could equally well be controlled from a drum machine.

Other electronic drum kits with varying features, sounds and facilities include those from ASAMA, TAMA, PEARL, MAXIM, HOHNER, ULTIMATE PERCUSSION (M&A as was), WERSI, KLONE, IMPAKT (bit of an antique now), CACTUS (which will qualify as a drum machine too if the sequencer option ever comes out), and ROLAND with a relatively new, versatile digital design.

On the subject of Roland, the same company market a set of pads which can turn your MIDI drum machine into a digital drum kit. Called the PAD 8 (formerly the OCTAPAD), the unit performs more or less the same function as a set of Simmons pads and a Sycologic or RMS Pads-to-MIDI convertor. On the PAD 8 you have the advantage of having the pads built into the interface unit, although of course this makes them fairly small, but the unit allows you, for instance, to flick to MIDI channel 1 to control a complete set of TR707 sounds, then to MIDI channel 2 to control percussion sounds on the bottom octaves of a DX7, then to MIDI channel 3 to control selected sounds from a Drumtraks. The possibilities are endless.

And, in an ironic reversal of history, the PAD 8 and units like it can also make your drum machine programming much more lifelike, simply because the beats are once again being determined in the old-fashioned way — by hitting something with a drum stick.