Allow me to pose you a question: what do you do when you find that even though you own a MIDI-equipped electronic drum set, you could do with more sounds? Well, you could plug directly into a synthesizer, or a modern drum machine, or better still you could invest in Simmons' SDE.

SDE stands for Simmons Drum Expander and what it is is an addon electronic voice unit, ostensibly like many others but tailored to be activated by electronic drum pads. (It's also biased in the direction of percussion sounds which is hardly surprising. However, it will also produce string sounds and other 'musical' noises.) So, you can have the sounds of marimbas and glockenspiels and xylophones and gongs and bells and cowbells and various other voices described simply as 'crash' and 'zing'! Of course all of these voices may be tuned up or down before programming a patch thus enabling many more 'tuneful and melodic' things to be played. Besides all of this, though, the company will supply you with ROM cartridges which contain 40 or 80 different sounds. (These aren't exactly on offer at 'give away' prices but they could save you a lot of work in the self-programming department.)

The front panel of SDE is a little daunting at first; you'll need a little while to get used to it. Having said this though, it probably took a while to get into electronic drums at first.

Anyway, to the left side of the rackmounted unit are a collection of rotary pots that control the parameters. Even though voices are produced via a complex system of mathematical formulae acting upon eight digital generators in the brain they still use only six parameters to change them. Below these are a corresponding number of LEDs which indicate triggering or in Programme mode the selected channel. The other side of the facia is totally devoted to displaying what the hell is going on. We have a large window to show us relevant info with LEDs below it to denote patch or voice as well as MIDI note or channel.

Alongside these are up and down data entry buttons and display which will cycle through the LEDs to find the information necessary for each programming option. Otherwise there's a select button which will allow you to change quickly between User, Factory and Cartridge banks. There are four of these designated A, B, C and D and it's in these that one can store up to 80 more voices. We can dump our composed voices to a RAM cartridge too if we want and as per usual a dot will miraculously appear in the display when we're using these.

Right in the centre are buttons marked Programme and Channel. The first one will tell you a thing or two about MIDI modes be they Omni or Global or what have you. (Omni is where MIDI channel info is ignored and MIDI notes will be recognised. Global notes are MIDI notes which take precedence and will send a certain note to an equally certain channel each time.) SDE also incorporates MIDI programme change and it has facility for 16 MIDI channels. I won't go into the whole thing about programming SDE if you don't mind but, suffice it to say, the Simmons handbook tells you how to do it in a fool proof way.

I mentioned patches earlier and SDE has a potential 40 of these, half of which are pre-programmed and the rest you may make up yourself. A patch consists of several bits of information: Volume and Dynamic sensitivity, Pitch, and MNSP (MIDI note selects pitch.) Additionally, the machine is set up so that each patch may have the choice of six sounds which can be triggered by different drum pads. And since these may each be tuned differently the possibilities would appear to be endless. You may also sequence these patches so that by stepping through them rapidly amazingly complex sound and pitch changes will be possible.

SDE is guilty of note-robbing too. This means that even though it can only sound six voices at once it can fool the listener into thinking that more is happening by stealing notes from previously used channels. It can only do this consecutively, but these notes can be from the top or bottom of the chord or even the next note in the cycle. I could go on to tell you all about Splits (different voices within the chord) and several other features but I'm sure once you've bought SDE you'll find out for yourselves! Likewise it's a little redundant for me to tell you how to operate SDE since you'll find that out too. Certainly Simmons' handbook tells you exactly how to go about these things.

The back of the unit is scarcely worth talking about since it consists of only an on off switch, footswitch socket, MIDI IN, MIDI Thru and Cassette; as well as an audio input and two 'outs'.

I mentioned at the beginning that SDE is meant to be used with a MIDI equipped drum set like SDS9 or SDS1000. But, should you haveonly a less sophisticated set, all is not lost. You may still interface it via MTM or TMI. These are Simmons products which will 'MIDIfy' your set and allow you to access all these other groovy sounds. This was SDE's raison d'etre in the first place.

The whole SDE package comprises the expander itself, a factory ROM cartridge, a MIDI cable, a tape dump lead and a guarantee card. If you're the sort of drummer who wants more sounds in his life and more life in his sounds then SDE is definitely for you!

Simmons SDE - RRP: £499