Oberheim Matrix 1000 (1988)

Oberheim Matrix 1000

 
UNDER THE HOOD
Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

Inside Oberheim Matrix-1000

 
MAIN DSP, ELECTRONICS, CHIPS PDF DOCUMENTS
CEM3396 74HCT32N CD4051BE Motorola 68B09

AM6012 DAC

     
IMPRESSION

The Oberheim Matrix-1000 is known for beeing an excellent 6-way polyphonic analog synth with the famous « Oberheim » sound. In fact, the Matrix-1000 is the rack version of the Matrix-6, itself renowned for the very rich sounding capabilities. The secret of this sound lies in the circuit used, the CEM-3396.
This circuit incorporates two DCO type oscillators, a 24dB / oct resonant filter and a VCA. Obviously, since this circuit is ultimately a synthesizer itself, all synthesizers using this circuit will sound globally in a similar way! The idea of ??the Matrix-1000 is to be a kind of « presets box » containing the most specifics Oberheim sound signatures. It is this idea of ?? »preset » machine that is dominant and which explains why it is not possible to directly program the sounds on this machine. Indeed, it will be necessary to use some libraries editors (mac / pc) to be able to program it, or to use an external programmer.

So what about the famous CEM 3396 sound ? Well, it is first of all a very particular sound due to the fact that each oscillator may use up to two waveforms combined : The first one is pulse (width adjustable) and square … We have a parameter to adjust a kind of mix between pulse to square waveforms. The second one also have a parameter to do a morphing  between sawtooth and triangle waveforms. Those two waforms can me mixed together to create a wide variety of complex sounds, using different combinations between those two waveforms. One can also generate white noise, detune the oscillators. Then comes the filter (LPF 24 DB), which is self-resonant. Classic filter therefore, but very soft. There are many routing parameters between the two oscillators, allowing FM synthesis from the two oscillators, there are also three envelopes, one dedicated to the filter, the other for the VCA but the third Can be used for other settings, which makes it possible to do things rather sophisticated (we are far from the series of Juno and their unique envelope). There are also ramps we can affect to specific synthesis features.).

Also we have the capability to cross-mod between the two oscillators, which will result as generating « FM » sounds (one finds this functionality on the Roland JX8P). But the main interest of the synthesis proposed by the Oberheim « Matrix » series is to use precisely a matrix (a sort of table) allowing to create a large range of modulations. It is therefore possible to use various sources (lfos, modulation wheel, ramp, envelope, velocity level, …) to modulate various destinations (oscillator pitch, filter cutoff, filter resonance, envelope level, etc.). This will create relatively complex sounds with lots of movements. But be careful to not overuse these routings, because sometimes the CPU (which manages these routings) is not always fast enough … This CPU is a Motorola 68B09 (or compatible) running at about … 2Mhz ! However it was the best 8bit CPU of its era.

The Matrix-1000 has arrived at the digital age, where synthesizers using digital technologies (the Roland D50 / D20, the Yamaha DX and the new Korg M1) were already very popular and very much dominant in the compositions of this time. Because in 1988 nobody really wanted to invest in analog technologies anymore, preferring instead digital technology which allowed to take new steps in sound researchs and to get rid of the strong constraints imposed by analog synthesizers (regarding sound design, polyphony, reliability, etc …).

However, some people wanted to still have access to a large analog sounds banks (presets era), where it was enough to « pick » a sound, to emphaze some sounds, or create some sound effects,… It is in that way the Matrix-1000 was generally used (a kind of large memory bank composed of 1000 sounds borrowed from the typically analog sounds of Oberheim).
Nevertheless, the Matrix-1000 is a real programmable synth that makes it possible to create sounds really very complex and rich!
For those who wish to be able to program the Matrix-1000 and to know the possibilities of its synthesis, it will be necessary to use the Matrix-6 instructions manual !

At the electronic design level, it can be seen that the motherboard is rather simple (especially compared to some others like Crumar Bit01, Roland JX-8P, …). This is partialy due to the fact that the 6x CEM3396 circuits enclose the DCOs as well as the filtering management. The CPU 68B09 manages the envelopes, the LFOs, and the modulation matrix (this can be compared to a kind of checklist the CPU runs while providing information to other circuits). The CPU will send all of its sound programming information to a special digital-to-analog decoder circuit (AM6012) and will send the appropriate signals to the various multiplexers / demultiplexers (CD4051BE) which will, finally, program the circuits CEM3396. It can therefore be said that this synthesizer uses a hybrid technology, like the majority of machines of that time. On one hand we have true analog items like oscillators and filters, with a digital management on the other hand. Probably the best of both worlds ! ;-)

One could just blame this synthesizer has only one audio output, thus monophonic. But this isn’t a real problem because during the production stage we can record the same mono sound on different channels, then recreate a wide stereo spatialization.