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Oberheim Matrix 1000

Article from Sound On Sound, September 1988

Looking for 'new' sounds? Martin Russ explores Oberheim's new Matrix 1000 analogue synth expander and discovers that digital isn't always best.

Looking for 'new' sounds? Martin Russ explores Oberheim's new Matrix 1000 analogue synth expander and discovers that digital isn't always best.

I'll only be five minutes, I promised the wife as I rushed inside with the cardboard box. After five years of mostly FM and occasional monosynthing, I was quite prepared to face up to having grown out of my youthful obsession with analogue polysynths, and this latest Oberheim release would be the final test.

Abject failure! Three-quarters of an hour later the wife stormed in and brought me out of my reverie. You've guessed it! Instead of losing my love of VCFs, the old passion had returned, stronger than ever! But what could possibly cause such a reaction in a committed FM user like myself?


The Matrix 1000 continues the third generation of Oberheim products - their original 2, 4 and 8-voice synths used a common two-voice module as their basic voice generation, while the second generation used a common two-voice circuit card inside products like the OB8 and OBX. The latest series have descended in complexity and price from the immensely powerful Xpander, released about four years ago.

The addition of a keyboard produced the Matrix 12, a 12-voice polyphonic monster keyboard providing both attack and release velocity, aftertouch sensitivity, as well as a stunning set of blue-green fluorescent displays driving assignable knobs and switches. The Xpander/Matrix 12 is possibly the single most powerful analogue synthesis module ever made - apart from the very large modular systems (but lots easier to use). More affordable versions - the Matrix 6 (reviewed SOS January 1986) and the rack-mount Matrix 6R - followed, but attracted only those with the skill and expertise needed to exploit the potential. (Even so, they have been extensively used in professional circles, especially in film score work.)

The Matrix 1000 brings the fat, warm sound of analogue synthesis within reach of mere mortals such as myself, and seems to be a perfect example of today's trend to produce products with ever more features for less cost. But enough of the overview, let's get down to business.


A conventional 1U high, 19" rack-mount case houses the Matrix 1000 in a sturdy jacket of steel. The black anodised aluminium front panel has a mains power switch, three-digit LED display, six Mode LEDs, 15 pushbuttons, and a volume control. Most of the buttons are devoted to a 10-key numeric keypad, with additional +/- incrementor switches and an 'Enter' button. The two remaining switches select the operating mode and help control access to the internal voices. The three-digit LED gives a clue as to the major feature - there are 1000 different sounds stored inside the Matrix 1000. 800 of these (numbers 200 to 999) are permanently stored in ROM, with the remaining 200 (000 to 199) kept in battery-backed RAM.

In these days of ever larger LCD displays, a simple LED display is quite a disappointment - as is the lack of a headphone socket (a first for Oberheim, I believe!). With 1000 sounds to listen to, it can be very, very difficult to try and associate a number with a sound, especially when Oberheim have only vaguely ordered the sounds. The first 200 locations (the RAM) contain a collection of 'the best of' sounds showing some of the possibilities. Everywhere else you seem to get a loose ordering rather than a completely random mix, but I could only really identify a few areas of comparative consistency.

The sounds themselves are about as 'state of the art analogue' as you could want. The noise floor is comfortably low in these digital days, and the only fault I could find quality-wise was a slight amount of zipper noise when I used pitch bend on some sounds. Apart from this, the sound is remarkably free from processing artifacts! You might be surprised at what a couple of DCOs, VCF and VCA can produce when combined with Oberheim's comprehensive modulation routing system - overall, it is definitely worth a good listen.


Auditioning 10 banks of 100 sounds can take quite some time. Pausing for a mere 10 seconds or so for each voice, a complete exploration will take just under three hours! Taking a cue from the Steinberg MT32 Editor/Librarian software, perhaps a similar librarian could be implemented as a desk accessory, so that you could choose from a selection of categorised named sounds without ever needing to struggle through the numbers? We shall see! [Is this a hint of more software from Martin? - Ed.]

Searching through the sounds has another advantage - it makes you very familiar with the front panel controls! The obvious way to select patches is by pressing a three-digit number on the keypad, and this indeed works - the Matrix 1000 powers up in the Patch Selection mode. The +/- keys can be very useful for small movements but for larger changes there are a couple of short-cuts. The Bank Lock button enables you to fix the first digit, so that if you are listening to the sounds in the 500 range (Bank 5), you only need to choose a memory in the 500s, and then press Bank Lock. Subsequently, only two keypad entries are needed to access any of the 100 voices in Bank 5. (This also works via MIDI, so that you can access memories higher than 127!) To change Bank, you can either turn off the Bank Lock (the left-most decimal point in the display indicates if the Bank is locked) and enter a new three-digit number, or you hold down the Bank Lock button and press a Bank number. Over MIDI, you just push the modulation wheel more than half-way up and send a Program Change from 0 to 9 for the appropriate Bank. (Controller number 31 can be used to exactly the same effect.) Once learned, the patch selection system is fast and actually very cleverly thought out by Oberheim - pity about the display though!

But how do you hear the sounds? And where are the MIDI sockets? On the rear panel, a single ¼" jack provides the monophonic audio output and there are the usual MIDI In, Out and Thru sockets. A fused IEC socket for the mains power input (a lead is supplied with the unit) completes the roster for the rear panel. This means that it's time to look inside!


Although designed by Oberheim in America, the Matrix 1000 is made in Japan by Hammond-Suzuki. As you would expect, there is a very high standard of construction, both mechanical and electrical/electronic. The double-sided, plated through hole, solder resist and silk-screen component legended Printed Circuit Board has an excellent layout and easily accessible test points. A small additional PCB is sandwiched behind the front panel and the steel case and supports the display and switches.

The Hitachi 6309 microcontroller has a 62256 32Kbyte static RAM chip, with battery backup for the read/write memory. A Mitsubishi 64Kbyte 27512 EPROM and 27256 32Kbyte EPROM provide the storage for the voices (Version 'PAT 1B' in the review unit) and operating system software (Version 1.09). A 6850 ACIA provides the MIDI interface, with a PC900 opto-isolator and filtered MIDI sockets.

With an LED display and six synthesizer voices to cope with, there are a lot of I/O ports needed, and these are provided by four Toshiba 82C54 bit-programmable I/O port peripheral chips.

In the audio section, the main synthesis power is provided by six Curtis Electro-Music chips - the CEM 3396. This is a single chip which provides a complete monophonic, dual DCO, VCF, VCA (etc) type analogue synthesis module. Multiplexing of all the modulation and control signals is provided by 12 NEC 4051 analogue switches, and the final audio outputs are summed into a conventional op-amp output stage. There is a single Digital-to-Analogue Convertor (a 12-bit NEC 6012), and this is associated with the only trimmer on the board (used by service engineers to set the zero volt offset). Considering that when I used to service synthesizers there were dozens, if not hundreds of things to tweak, this is a good example of the advances in technology over the last 10 years. Calibration of the Matrix 1000 is thus a software rather than a hardware task, and so the lack of adjustments needed combined with the simplicity of the circuitry should produce a reliable unit - I only used the calibration routine because SOS reviewers always try everything!


The front panel has one remaining control - the Mode Select button. This cycles through the six available operation modes of the unit. The default mode is the Patch mode for selecting sounds. The Channel mode is used to select the MIDI channel and MIDI mode, and can be set to Mode 1 (Omni mode, where the voice messages are received from all channels), Mode 3 (Poly Mode, where only voice messages on the selected channel are received) and Mode 4 (Mono mode, where six channels are used, each containing monophonic voice messages - as used in guitar synthesizers, where separate information for pitch bend is required for each voice/string). The global Fine Tune mode does exactly that, with 63 steps covering a range of a semitone.

The Group mode is used to determine the note assignment by indicating how many Matrix 1000s are connected together. If two units are available, then setting the value to '2' on the master unit enables alternate notes to be played on the master and then the slave, thus doubling the polyphony to 12 voices. Up to six Matrix 1000s can be connected together in this way.

By assigning two or more units to different positions in a stereo field, it is possible to overcome the basic monophonic output limitation. And, in fact, you can use any expander in Group mode, since the MIDI Out sends the appropriate voice messages just as normal. I found the Group mode to be a simple way of producing complex assignments of timbres - the alternate assignment of notes to the Matrix and then the external expander is especially useful, rather than the more common Overflow assignment, where the MIDI expander only receives notes when the controlling unit has used up all of its own polyphony.

The Data Dump mode enables single voices, any bank, or just the RAM memories to be sent via MIDI. The final mode contains useful additional routines under the general heading of External Functions.

In this mode, the numeric keypad selects the function and the +/- buttons alter the value, whilst the Enter button toggles values on or off when appropriate. Function 0 sets the Unison mode, where all the voices play simultaneously for a single incoming voice message. This produces a rich, fat monophonic sound. Function 1 allows Transposition up or down by up to three octaves. Most of the functions are global settings for the whole unit, and are stored in the battery-backed RAM.

Function 2 controls the misleadingly named MIDI Echo mode. This is actually just the software Thru facility found in many Sequencer programs, where the incoming MIDI information is sent to the Thru and the Out sockets. It thus allows layering of sounds from more than one Matrix 1000. Group mode has a higher priority than the MIDI Echo, and so you can switch between layering and the Group-based polyphony by turning the MIDI Echo on, and then switching the Group mode on and off by means of the Enter button whilst in Units mode. Another example of forethought by Oberheim resulting in a very useful facility.

Function 3 inverts the sense of the MIDI Volume controller (number 7) so that you can use some guitar synth controllers or perform crossfades between sounds on a controlling keyboard and the Matrix 1000.

Function 4 sets the assignment of the Pedal controller. This defaults to controller number 4, which means that many controlling synthesizers can use their pedal to control the Matrix 1000, but it can be set to any MIDI controller you like, from 0-121 - even the Volume controller - but this then overrides the dedicated MIDI Volume control. I only found about half a dozen voices which used the Pedal controller, so there is plenty of scope for editing the RAM memories. The Matrix 1000 responds to velocity, aftertouch, pitch, breath and modulation controllers, as well as sustain pedals.

Function 5 displays the unit number used in Group mode, and Function 6 turns the memory protect on or off - data dumps can only be received when memory protect is off.

The final Function is number 7, and this provides calibration and factory test options. A power-up 'hidden' command provides a 'panic button' and resets the internal functions to default values.

In addition to the Matrix 1000, you get a 50-page A5 owner's manual, MIDI cable, mains cable and voice name sheet. The manual takes you through all the operations of the unit, although mine did not include a MIDI Implementation Chart, and it omits any mention of editing the RAM voices except by transferring them to and from a Matrix 6 or 6R (the voices are compatible). I understand that there are software packages available for the Atari ST from Dr. T and C-Lab which can edit the RAM memories in the Matrix 1000.


No piece of equipment is perfect, and the Matrix 1000 has a couple of minor imperfections: it does tend to get rather warm when mounted in a rack - Oberheim recommend leaving a gap of half an inch or so between it and any other units. The Bank Lock button can also be used to mute the Matrix 1000, but this only mutes any notes currently being played - any new Note-On messages will sound as usual, which detracts from the usefulness. Having a volume control on the front panel is also very useful because of the wide variation of level in the sounds. No problem in the RAM-based editable sounds, but the velocity sensitivity on some of the preset sounds is fixed at too harsh a level for my fingers - perhaps that's because the sounds are a compilation of the best patches submitted by Matrix 6 owners?

The Matrix 1000's lack of multitimbrality is more than made up for by the ease of use, the price and the sounds. I am sure that some multitimbral expanders are so complex that very few users will ever be able to exploit them effectively.


It is nice to see that Oberheim have lost little of their old magic. The Matrix 1000 provides excellent coverage of the classic analogue sounds - an ideal contrast to the clean, clear precision of current digital sounds. The wide and varied possibilities of the Oberheim Matrix Modulation based synthesizers means that there is plenty of room for the adventurous to explore the sound potential of the Matrix 1000. Careful thought in the design stages has resulted in some outstandingly useful facilities, making this an easy to use expander, unlike some examples in the genre. The Matrix 1000's flexibility, especially the Group mode, mean that it can be used as rather more than just another expander.

But best of all are the sounds - a complete contrast to any of the digitals. Warm, smooth, moving synthetic textures with a life and character all their own. For me it was a case of 'deja vu' and 'love at first sight' all over again: instant infatuation! How could anyone resist such a delight!

Price £449 inc VAT.

Contact Sound Technology plc, (Contact Details).


Programs 800-899 concentrate on special effects, and I recognised sounds remarkably similar to those in some recent (and not so recent) feature films, as well as from quite a few computer games with sampled sounds.

700-799 contain mostly bass sounds, ranging from those with sharp extreme timbre changes to some very smooth acoustic feeling burrs. Most of these exploit the characteristic analogue bass chorus sound by detuning the two Oscillators and adding Pulse Width Modulation, which cyclicly alters the tone and adds a surprisingly effective rolling quality to the sound.

600-699 contain mostly string-type sounds, although they do stray into brassy regions occasionally. Programs 500-599 contain lots of brassy sounds, from the traditional raspy VCF-derived sound, through to the very detuned, sharp JP/JX brass sounds.

Elsewhere there are some good electric pianos, any number of synthetic washes, and a few nice orchestral instruments. Particularly impressive are the vocals, which use filtered noise with other sounds. Overall, this is a dynamic synthesizer which has some impressive and unusual sounds.

Program 343 - a song opener if ever I heard one!
354 - a Lyle Mays sound-alike.
364 - the 'classic' aftertouch S/Hold filter sweep.
387 - the big fat synced Oberheim sound.
467 - JP/JX Brass
825 - an ethereal ending! (Hold a chord)

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Dr.T's Software Page

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Practically FM

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

The current copyright owner/s of this content may differ from the originally published copyright notice.
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Sound On Sound - Sep 1988

Gear in this article:

Synthesizer Module > Oberheim > Matrix 1000

Gear Tags:

Analog Synth

Review by Martin Russ

Previous article in this issue:

> Dr.T's Software Page

Next article in this issue:

> Practically FM

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