Tom Oberheim was one of the trailblazers of analogue synthesis with his eponymous synths back in the 70s. Then, one day he arrived at work to find his company belonged to his lawyer, in a classic 8Os-style sting. Fazed by this unethical usurping of his life's work, Tom went back to the nuts and bolts of sound synthesis and formed a new company.

Today, his synths are badged Marion Systems, after his daughter's middle name. The first fruit of Tom's labours is the Marion Systems 2, an analogue synth consisting of up to two of Tom's modular ASMs, or Analogue Synth Modules. The idea behind the MSR2 is that you can either have two of the ASMs, or add another synth module for new effects. The first such module will be a Wavestation SR under licence from Korg, with other modules in the pipeline.

Meanwhile, Tom's newest effort is the ProSynth, a one-module version of the MSR2, without the expansion capabilities of the MSR2 but available for a very reasonable £699. For that, you get an eight-part multi-timbral, eight-note polyphonic analogue synth, with editing parameters mappable to MIDI controllers. This offers realtime control of filter cut-off frequency and envelope settings, for that ultimate 90s buzz.

Always an innovator, Tom's ASM board consists of an exclusive set-up he calls HRO for High Resolution Oscillators. He explains:

"The problem with analogue synths in the early days was always the stability of the tuning. Unstable control frequencies meant that tuning resolution was never very high either. With the ASM, what we have done is design several custom chips, which solve the problem of unstable tuning, and give us a tuning resolution of up to 0.2 of a cent. The modular system is designed with two Motorola 68000 CPUs running on two separate motherboards. One is for the global stuff, MIDI, patch settings and so forth, while the ASM comes with its own CPU to handle the synthesis side of things. This lets me take a timing signal from the MIDI clock, and send two of these out to each custom DCO on the ASM board, for completely stable timing and tuning resolution."

The ASM boasts eight HROs, in other words eight DCOs each receiving two timing signals, which provide it with its eight-note polyphony. As in most digital synths, you can either stack up these voices in performance mode, for one of the biggest fattest analogue synths you have ever heard, or utilise multi-mode, where note allocation is dynamic.

This way, you can play chords alongside basslines and drum sounds. The sounds are nothing less than sensational. From analogue-style drum and percussion sounds which could seriously dent the market in second-hand 808 and 909s, to filter swept pads and gut-wrenching analogue synth basses, the ProSynth has all the sounds you need. Unlike some recent attempts to package a variety of analogue style sounds in a box, these are the real thing, full fat analogue sounds with full editing facilities, and up to five real-time controllers for recording those filter sweeps and envelope changes into your sequencer.

There is a four pole low pass filter with resonance control, three envelope generators and three LFOs to play with from the editing pages or MIDI controllers, and Tom has even got a Mac or Windows editor for the ProSynth, which retails at a very reasonable £50. As Tom tells it, "The aim was to re-capture the sound of the OBXA and four voice Oberheim, which are my personal favourites, along with the punch of the Matrix 12 and Expander."

This Tom has certainly achieved. The ProSynth and the Marion could almost have been designed with the European techno scene in mind, yet Tom is a mature gentleman from America. What was the demand for analogue synths in the States?

"Amongst musicians, there's a lot of interest. The problem in the States is that most product is sold by box-shifters who operate primarily by mail order. They are quite happy selling boxes full of preset GM-type sounds, as the customer doesn't have to come in and hear the thing to know what he's getting. With my synths, it's essential you play around a bit, to see just what it's capable of. That doesn't fit in with the box-shifters' philosophy, so we've got a few problems in the States. But the interest is there, definitely."

Tom had just been over at Musikmesse in Frankfurt, and had found a very receptive audience for his ideas, as he explained:

"This techno music is absolutely fantastic, it's finding ways of using all those weird noises we came up with back in the 70s which no-one knew what to do with. I love it! It's opened my eyes to a few things too. We've only provided one set of stereo outs on the back, as the American market is quite happy working that way, sending everything from a module into their desk as a stereo mix. The first question everyone in Germany and here in England has asked me, is whether they can have multiple outputs at the rear, for extra EQ'ing at the desk. This is something I'll be looking into providing when I get back to the States."

With a mind that never seems to stop working, Tom loves sound, and is constantly thinking up new ideas. We were discussing jungle music's use of ring modulators, and the fact that digital ring modulation is only an approximation of the real thing. It's one reason why the old units are so sought-after.

"The first item I ever produced was a ring modulator. I think they make a fantastic sound. Now you've got me thinking, how could I incorporate a ring modulator in the voice architecture of a synth? A ring modulator has no sound of its own, but completely takes over a sound once it is activated. If I drive a ring modulator with a DCO..."

With that, he was off planning a new circuit, jotting his ideas down on a scrap of paper, a great mind and a great man.