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Oberheim Matrix-6

Article from Sound On Sound, January 1986

Flying in the face of fashion, Oberheim's new Matrix-6 polysynth utilises traditional analogue voicing and offers some of the most powerful and versatile sounds around. Keyboards man Paul Wiffen checks out its pedigree.

Flying in the face of fashion, Oberheim's new Matrix-6 utilises traditional analogue sound generation and offers one of the most powerful and versatile synthesizers available. Keyboards man Paul Wiffen checks out the pedigree.

Eighteen months ago, a new synth module appeared on the market and caused something of a sensation. Not because it represented the latest in digital synthesis, which (in the shape of the DX7) was ruling the roost at the time; not because it made sampling more accessible to the average musician (this was still out of reach to most), and not even because it was cheap.

At £3,750 it certainly wasn't that...

No, this module was a six-voice analogue synthesizer housed in an unassuming box which looked more like an Oberheim sequencer or drum machine.

Why all the fuss then? Simply because it gave the largest ever available voice creation possibilities outside a studio modular synth system, combining old established analogue features like filtering and the latest digital techniques of waveshaping and FM, together with velocity and pressure sensitivity. In a market dominated by Yamaha, and soon to be hi-jacked by the sampling keyboards, where it seemed to be impossible to sell anything over £2,000, it sold, sold well and continues, eighteen months later, to sell well today. Bill Aitken of SynthAxe said it was the most effective synth to use with their product, and even a sax player like Gary Barnacle used its CV to MIDI capabilities to make it the heart of his synthesized set-up in tandem with his instrument's acoustic sound. All across the board, the Oberheim Xpander (as the astute amongst you will already have guessed) was an enormous success.

Next, Oberheim took two of them, together with a weighted wooden keyboard, and combined them in a 12-voice package called the Matrix-12, which was enough to make even blase, seen-it-all synthesists like Andy Richards drool. However, this did nothing to alleviate the weight of the price, now a cool six grand or so.

The Matrix-6, instead of doubling the Xpander's price (as did the Matrix-12), makes the same sort of facilities available at half the price.

Yet, incredibly, it delivers a velocity and pressure-sensitive keyboard as well, all for £1,750. So how is this achieved?


It is a fact of modern day synthesis (be it analogue, digital or sampling) that it is often not the sound quality which costs the money, but access to it. Yamaha's DX1 was prohibitively expensive, not because it gave you much more than two DX7s, but because you could see what you were doing, whilst their TX modules bring the cost of DX7 voicing down to £500 apiece but without parameter access, except through MIDI. By the same token, the Prophet 2000 which sounds better than the Emulator II in my view, doesn't have the same programming display and separate outputs, so it costs less than a quarter of the Emulator's original price.

The hard fact of the matter is that soon the knobs on the front and the jack sockets on the back of keyboards will cost more than all the technical wizardry inside, which in any case is 90% software these days, and its development cost can be split across all the units you ever hope to sell. It is no coincidence that each new synth and/or drum machine that comes out has fewer knobs and outputs, while at the same time their internal capabilities seem to multiply exponentially.

And this is exactly how Oberheim have achieved this remarkable reduction in cost. Gone are all the pots, and the long LED switches from the front panel of the Xpander and many of the separate inputs and outputs from the back. In fact, the front panel of the Matrix-6 would look as blank as that of the Ensoniq Mirage if Oberheim hadn't decided (as Ensoniq should have done) to list all the parameters on the front for immediate reference (hands up all those who hate that bit of plastic-covered card you get with the Mirage?).

However, the internal capability of the Xpander voicing has not been reduced one jot and the factory patches supplied in the Matrix-6 testify to this fact. There are many sounds here which have not changed even in name from those of the Xpander: hard FM piano sounds, strident brass and silky smooth strings (both of which hark back to the halcyon days of the OB range), fat bass voices and splendid pure synthesizer sounds which herald real creativity instead of mere imitation. My personal favourites are those sync-type sounds, much beloved by a certain Mr Jan Hammer. The inherent flexibility of the voicing system allows you to go further in that direction than ever before... boldly, of course.


The programming of the instrument is done by the now familiar Parameter/Value system using touch membrane switches both for keypad, incrementer and mode selector functions. Personally, I really hate membrane switches. Still, if they can make such significant price decreases, who's complaining? Certainly not me.

You select between three main modes: Patch, Split and Master - Patch and Split both having several sub-modes.

The first Patch Select allows you to step through the voice patches stored in the machine using the < > incrementer, or call up a particular one by hitting a two digit number on the keypad. This can be a bit awkward if you miss as you need to hit both numbers again. Still, a little care and there is no problem. The names and numbers of each patch are shown in the display.

Patch Edit accesses the 95 Parameters which make up a basic patch and then by moving to the membrane Value switch you can make changes. This slow process was just beginning to get on my nerves when I noticed the Quick option. This makes the incrementer section select the parameter and the keypad changes the values. Whilst this is a vast improvement on switching constantly between Value and Parameter, I can't help feeling that the incrementer would be better used to change values whilst the keypad would be more effective for jumping between different parameters. Still, that's only my opinion. What do you think?

Matrix Mod is the other Patch sub-mode and this gives access to the Aladdin's cave of the Matrix-6. But, he said tantalisingly, we'll look at that later. The Split Mode has two sub-modes also which are identical in concept to those for Patch. The Split Select option shows the patch name and number (there are 50), and allows them to be stepped through or called up by typing, whilst the Split Edit mode allows the parameters of the currently selected split to be changed.

The incrementer knobs < > move up and down in single units whilst those marked « » do the same in units of five. Pressing both >» together goes up in tens («< together goes down in tens). This saves a lot of waiting about, providing you can manage the different size steps. Still, practice makes perfect.

Having heard the excellent factory preset sounds, I could not resist trying to create some of that ilk myself though I soon came face to face with the reality of the Matrix-6. With all these parameters, it is tricky to know where to start (95 just for the Patch Edit, to be precise). However, keeping a level head (the basic axiom in these circumstances - too many people think 'I'll never cope with this' and give up), I picked a factory patch and began to edit it.

After a slow start, I soon found myself adding vibrato using pressure. Pulse Width Modulation from LFO 2, and adding a 'harder' sync to DCO 1. Now these terms are merely a taster of what editing on the Matrix-6 is like. It is most definitely not a synth for the beginner. But having said that, I doubt there are many things you might want to do that it cannot cope with. It seems fairly logical that to synthesize complex sounds, you need a complex synthesizer - and the Matrix-6 is certainly that. I found myself longing for routing diagrams like those on the Xpander's front panel (God only knows where they would have put them!), but these are not even included in the manual. Consequently, to confidently programme sounds on the Matrix-6 you need a fair old knowledge of how the various components of a synthesizer tend to interact. I, of course, in my capacity as a keyboard programmer, am supposed to know about such things, but even yours truly found the profusion of jargonese (particularly in the abbreviated form in which it appears in the Matrix's LED programming display) a bit daunting.

The conclusion I reached from this, is that you will not get more than 0.05% of its potential out of the Matrix-6 unless you sit down and read the manual from cover to cover. Now I know that some of you are genetically incapable of anything as mundane and I therefore advise you lot to stick with your Juno 106. But for those of you who want to expand your synthesis horizons, it is a fascinating and severely educational experience. It can open your eyes to a whole new area of synthesis not to mention rendering ridiculous the notion that analogue synthesis is 'too limited'.

Sometimes though, I can't help feeling that the parameters are deliberately labelled a little obtusely. Why call Parameter 22 'FREQ MOD BY ENV 1' when we all know it as VCF ENV AMOUNT, or 29 'VCA2 MOD BY ENV2' instead of AMP ENV AMOUNT. It also seems to me that it wouldn't have hurt to subtitle ENV 1 with Filter and ENV 2 with Amplifier, so that people who are familiar with other companies' synths are not completely flummoxed.

Nevertheless, despite my complaint about nomenclature (or whose jargon you use), one thing is certain: Oberheim certainly leave no stone unturned, as far as synthesis is concerned.


Although no review of the Matrix-6 could do full justice to the possibilities (unless it exceeded the 100 pages of the manual), we should at least look at the basic voice channel to get some perspective on the flexibility of the system.

This begins with two analogue oscillators (you can tell because an auto-tune routine of up to five seconds is still necessary) which are referred to as DCO 1 and 2 (Digitally Controlled Oscillators) to show the fine degree of control available over them. They can be detuned from each other or synced together. Basic waveform choice is Pulse and/or Sawtooth, but Pulse Width and Shape controls are available to give an infinite number of variations, all with their individual harmonic content. Pulse Width Modulation is available from LFO 2, while LFO 1 can produce pitch modulations such as vibrato or even FM (more confusing jargon with 'FREQ MOD BY LFO1', which covers all pitch modulation, not just FM).

The VCF/VCA section covers the usual filtering and loudness controls in conjunction with ENV 1 and ENV 2 respectively, but adds the control from keyboard velocity and pressure as well. ENV 1,2 and 3 (which is used for FM amongst other things) all boast delay, LFO or external control and different trigger responses in addition to the normal ADSR functions.


In an interesting variation on standard FM, the Matrix-6 uses the filter as an oscillator (by turning the resonance to full) and is hardwired to DCO 1 for its FM mode, with the sawtooth wave permanently selected. This makes it an either/or situation vis-a-vis analogue synthesis, but then you can always double two sounds together. Interesting effects can be created, however, particularly with large FM amounts, whilst smaller ones tend to give more musical results. The FM amounts can also be controlled by velocity and pressure. A worthwhile section to include this, especially for the investigative synthesist, but don't expect to create DX7-type sounds straightaway. Yamaha's FM voicing is, after all, much more complex than this.

The LFOs (two of them) are not your run-of-the-mill vibrato jobs either. Each can be modified by the keyboard or ramps or lagged (nothing to do with hot-watertanks - it means delayed), as well as having six waveforms available. If this is not enough, the LFO can sample any other modulation source and use that as its waveform. Whilst nothing to do with sound sampling, it is nonetheless a fascinating technique for more progressive stuff. That just about covers the basic Patch Edit parameters, although somewhat thinly. However, as if this plethora isn't really enough, there is the splendid Matrix Modulation System to fall back on.

Developed exclusively by Oberheim, this sort of flexibility seemed to have been lost for ever since the decline of the studio synth system with the old patch cables. But Oberheim's system means that we can go back to the techniques of trying outrageous routings just to see (or hear) what happens. As they proudly announce in the manual, this system gives 1.2 x 1042 possible modulation combinations. That should keep you going until tea-time! So how does this system work? Well, in addition to those 'hard-wired' modulation routings we saw earlier (ENV 1 to VCF, LFO 2 to PWM, etc), you can select any one of 20 modulation sources and send a variable amount to any one of 32 destinations. This should cover most eventualities!

Realistically, you could spend the rest of your life investigating the possibilities of this section, and whilst I don't advocate this (unless you're looking for something to take with you to the late, great Mr Plumley's Desert Island), a couple of weeks would not be wasted and at the end of it your synthesis horizons would be considerably expanded.

You can use up to ten of these 'custom' modulations in each patch, personalising a synth voice to previously unavailable levels. So no two programmers' sounds need ever be the same. This system of Oberheim's won't be out-dated, even when FM synthesis and sound sampling have out-lived their usefulness!


Once you have settled on a voice patch (or patches), then you can begin to combine them together into 'splits' and 'doubles' (all referred to as 'splits' by Oberheim). But without wishing to sound predictable, it seems hardly worth mentioning that Oberheim's idea of a split is a good deal more flexible than the standard split/double synth. Even the split point bears witness to this.

Rather than simply setting a split point, you specify a lowest and highest note for both right and left (upper and lower) voices. But this is not merely restricted to the five octave keyboard of the Matrix-6. All ten octaves of MIDI assignment (note numbers 0-127) can be used, so that the keyboard of the instrument can be used to play one sound, while incoming sequencer data or a master keyboard can trigger notes above or below the five octaves in front of you. These ranges can also overlap completely or partially as required, giving rise to what we would normally call 'doubled sounds'.

Each of these ranges can have a separate transposition amount and can also send or receive on independent MIDI channels as required. All these features can also be selectively cancelled, so that one side is non-transposed but receiving MIDI on channel 5 whilst the other is transposed but played on the keyboard with MIDI being ignored.

Not only can you adjust the balance of volume between the two patches, but also the number of voices in the split. You can even assign no voices at all to either range so that only an external MIDI synth is played from that range. My only complaint here is that the six voices cannot be split 3/3, which is obviously the most useful for 'doubled' sounds (where both patches are played in the same range). Still, no-one's infallible are they?

This section governs the general set-up of the instrument. Here all general parameters for performance, such as overall velocity sensitivity and vibrato type, as well as all MIDI parameters and Cassette Interface operation, are controlled and marginally vital processes such as Auto-Tune and Master-Tune are carried out. Handy section this!


Despite the occasional oversight (like the lack of evenly distributed 'double' assignment) and a confusing tendency to jargonese which might deter the less than completely serious synthesist, the Matrix-6 makes an unprecedented number of features and modulation routings available at a price which would have seemed incredible only twelve months ago.

Unfortunately, this price now puts it right in the middle of the sampling keyboard market, towards which 99% of all keyboard players will be rushing lemming-like (just like they did to the DX7 eighteen months ago). My sincere hope is that the other 1% (and some of those who tire quickly of perfect strings, perfect brass, perfect pianos) will buy the Matrix-6 and through it rediscover the true creativity of synthesizing your own sound, rather than sampling somebody else's.

The internal sound structure of the instrument, whilst rivalling the complexity of the DX7, starts from a base which most of us are familiar with and builds upon that experience, making even the most versatile synthesist more capable and given to experiment. The Matrix-6 deserves considerably more than the six month run of the current market favourite. The Matrix-6 will give you a lifetime of creative synthesis.

(Contact Details)

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Effective Automation

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All Under Control

Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

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Sound On Sound - Jan 1986

Gear in this article:

Synthesizer > Oberheim > Matrix-6

Gear Tags:

Analog Synth

Review by Paul Wiffen

Previous article in this issue:

> Effective Automation

Next article in this issue:

> All Under Control

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