Talk "classic" synths and you can't avoid the Minimoog, yet there are other Moogs hiding in its shadow which deserve a little of the Minimoog's limelight - one of these is the Multimoog.

No matter how you look at it, for Moog at least, the Minimoog was a hard act to follow. Everything had worked out so well: the ergonomics, the architecture, and above all the sound. Such was its success that it was difficult for any manufacturer - including Moog themselves - to better it. But they had, at least, to try. One of the resulting instruments was the Multimoog.

Briefly, the Multimoog is a two-oscillator monosynth with aftertouch - or pressure-sensitive keyboard. The keyboard is one of the ways in which Moog thought they'd be able to tempt people to trade in their Minimoogs. For something like a bassline, aftertouch may not cut much ice but for lead lines and sync or filter sweeps, pressure sensitivity can be used to devastating effect.

Many of Moog's instrument release dates are shrouded in the mists of time (for me at least), but the Multimoog appeared somewhere amongst the other early pressure-sensitive monosynths. Moog produced a sister to the Multi in the Micromoog, which appeared in '75, and the Multi appears to have followed closely behind. The Micromoog doesn't share the Multi's pressure sensitivity, has a single oscillator, but also a sub-octave splitter (like the Roland SH1). The filter can be pushed into self-oscillation and made to track the keyboard to generate a sweet, resonant sine wave. The Multimoog was the "go faster" version of the Micro, sharing its styling and a lot of the same basics, but possessed of a great deal more besides.

For one thing, there are 44 notes on the Multi's pressure-sensitive keyboard instead of the Micro's 32. For another, there's a second oscillator - essential if the Multimoog was to come near the Minimoog's sonic potential (the Minimoog has three oscillators, if you press the LFO into service as a VCO). The oscillator instability which had been the curse of early Minimoogs is dealt with in both instruments by using circuitry which runs well above ordinary room temperatures - and heating the circuit. This requires a warming-up period of a minute or so before the synth is stable, but is unaffected by subsequent fluctuations in ambient temperature.

The pressure sensitivity uses a rotary control for setting the amount of effect which pressing the keys produces. Unlike some of the other pressure-sensitive monos, the system can only really handle one "pressure effect" at a time, but the Multimoog scores in that the options are all pretty musical: you can pitchbend or modulate either Oscillator A (for Oberheim-type lead guitar effects), the filter (for extra brightness or growl), both oscillators, or all three. You can also alter the sync relationship of the oscillators or you can make Oscillator A's waveform more of an equal mix of sawtooth and square wave - subtle but effective.

More modulation potential exists in the form of the mod wheel. This can call on any one of six sources to modulate four of the same destinations as the keyboard (except this time it's the other oscillator's waveform which becomes progressively more full-sounding) and can cross modulate with the pressure sensitivity. Instead of the Minimoog's pitch wheel there's a pitch ribbon. With this you have to start a bend at the zero-point (halfway along the ribbon) and return to it in order to get a smooth bend. It's not as convenient as the CS80's ribbon, which treats your first point of contact as the zero-point. One trick unique to the Moog ribbon is that of playing a trill by hammering on and off the ribbon at the required interval from the zero-point.

There's just one control for setting the octave for both oscillators, although this is offset somewhat by being able to detune Osc A up or down a fifth, and further by another fine control. As well as 2' to 32' positions, there's a setting called Wide Freq. This sweeps the entire frequency range with the associated rotary control. As on the Micromoog, there's a sub-oscillator which, in this case, also syncs to Osc B via another rotary control.

"The Multimoog is not quite as sweet-sounding as the Minimoog, but seems somehow more 'immediate' - more '80s and certainly more '90s."

One excellent feature is that the rotary waveform selectors aren't click-stopped, so there's a gradual change from sawtooth through to square and then pulse waves. The disadvantage with this is that you can't readily switch in an exact wave setting. But even this is more than made up for by the ability to use the knob as a performance control. And you can do it with both oscillators at once.

A three-position slider labelled Norm Drone Off switches the oscillators out altogether (for filter and/or noise effects) or gives a constant drone. The drone is quite effective when used with glide - which also has an on/off switch and glide time rotary control.

Rather than the usual ADSR format, the Multimoog's transient generators are AR (Attack/Release) envelopes with switchable sustain. There's no sustain level as such - switching sustain in simply holds off the decay phase until key release. It's worth bearing in mind here that the Minimoog itself used an unconventional arrangement which involved attack and decay times, a Filter Amount control and a sustain level - the decay time setting served as both decay and release times in the ADSR format. It's fairly clear, however, that the Multimoog and Micromoog's envelopes owe their design to this. For speedy changes, there's also a defeat switch to cut release times - handy for making basslines instantly snappier, for example. Used intelligently, these switches - along with a couple more we'll come to presently - go a long way to compensating for the Multimoog's lack of programmability by facilitating quick yet drastic patch changes.

One surprise the Multimoog has in store comes with the VCF envelope Amount control. A lot of synths enable you to invert the filter envelope with a switch, so that whatever envelope is set works as a negative voltage, lowering the filter cut-off point. But on the Multimoog, in the same way as the waveform is totally variable, so the filter can be swept from positive, through neutral, to negative, with none of the discontinuities that a switch provides. It's a nice feature to have around.

Another nice feature capable of producing what can only be described as nasty sounds lies in the Multimoog's Filter Mod By Osc slider switch. This switch is marked Off/Weak/Strong and places the input of the filter under varying amounts of control from the oscillators' output, and can be used to produce ring-modulation effects. The behaviour of the filter itself is modified by another slider switch marked Filter Mode. Again there are three settings which assign 0.5v/oct or 1v/oct in Normal or Full modes, and pushes the filter into self-oscillation in Tone mode. The effects of using Filter Mod are enhanced if either Full or Tone Filter Modes are selected.

Until you encounter these two switches the Multimoog performs quite predictably and musically. Once these are called into play, however, it assumes a role more commonly associated with larger, even modular, synth systems.

"The Moog sound is there, and the possibilities for modulation effects, bleeps, blurts and dynamic changes of sounds are practically endless."

Like so many of the modulation and interconnection facilities on the Multimoog, these features make it a synth ideally suited, not necessarily to live performance, but to studio performance. This could involve playing it in real-time, or playing it with a sequencer via a MIDI/CV interface, possibly with extra control input in real-time.

On the rear panel there are inputs for control voltages for the filter, the two oscillators, and the destination to which the pressure sensitivity is routed. Short of a modular synth, VCS3 or Matrix 12, there aren't many synths with this sort of flexibility. Talking of interfacing, there are input and output sockets for CV and S-trigger too, so it's possible to hook a Multimoog up to a MIDI system, using a MIDI/CV interface like the Groove Electronics M2CV or Roland's old MPU101. You'll have to find Cinch-Jones plugs to slot into the trigger sockets, however, unless you open it up and fit a jack as an alternative.

The rear panel also hosts a couple of sockets for footswitches for modulation and glide - but, as on the Minimoog and Polymoog, they're smaller than standard jacks (but larger than 3.5mm jacks). There's an audio input, which allows an external signal to be processed by the Multimoog's filter and modulation sections. Uses of this are many and varied, and include chopping up a rhythm guitar and doing "interesting" things with voices. It's the sort of facility which continues to ensure analogue synths a place alongside today's digital master-pieces.

As with so many old (analogue) synths, interfacing the Multimoog with the outside world can be traumatic, and setting up a sound without a memory facility is an art in itself. But it's all worth the trouble because of the sound it produces and the fact that the Multimoog makes it easy to do things that more modern synths just don't encourage you to do.

Against the other two-oscillator Moogs, the Multimoog has more to offer than the Prodigy - its keyboard size and sensitivity, its modulation possibilities, and the provision of noise, sample-and-hold and the ability to process an external sound. It has advantages over the Source, too - it doesn't have memories, but it does have knobs, and one of the prime advantages of old analogue synths must be that they can be edited in real-time.

As with any instrument, the all-important question is what does it sound like? The simple answer in this case is - like a Moog. It's not quite as sweet-sounding as a Minimoog, but seems somehow more "immediate" - more '80s and certainly more '90s. But the business of comparing analogue synths is a bit like wine tasting. The only real test is a blind test, where instruments are assessed on their sonic merits in the hands of a capable player. I've only once played the Multimoog and Minimoog side by side, and felt that the Minimoog had the edge - but that's a personal judgement. The two are different, certainly, and if there isn't quite the warmth or bass solidity of the Minimoog, or that feeling of being somewhere between clarinet and soprano sax, there's a lot which the Minimoog doesn't have. You can find examples of the Multimoog on record with After the Fire, whose Peter "Memory" Banks made extensive use of the synth's pressure sensitivity. The Micromoog, meanwhile, found favour with Thomas Dolby (in his Golden Age of Wireless period) and Japan's Richard Barbieri (on most of their best-known LPs).

With its black moulded plastic facing, metal back, and chipboard base and sides (with fablon woodgrain side panels) it's not as pretty as the Minimoog, but it's still a pleasant-looking instrument with just a hint of the styling of the old modular Moogs. As with the Prodigy, the white slider switches feel delicate but, like the rest of the hardware, are actually very sound. The pressure sensitivity is effective and reliable - it's operated by a cushioned bar that stretches the length of the keyboard and sends a control voltage proportional to applied pressure.

If you've been brought up on DX7s and M1s, and you're looking to explore analogue synthesis, the Multimoog will offer you considerable power in a manageable and expressive instrument. If you're ready to get some serious mileage out of analogue technology, then the Multimoog might be an ideal choice. The superb Moog sound is there, and the possibilities both for weird modulation effects, bleeps and blurts and for dynamic changes of sounds are practically endless. These changes can be subtle or violent, sudden or almost imperceptibly slow.

Whether you'd enjoy the Multimoog is down to how you want to play the keyboard and whether you want the control offered by that "analogue institution", the knob. The Multimoog's got 22 of these, and, as Roland acknowledged with their JD800, they're a useful innovation.