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The back panel of the Matrix-12 is where all of the synthesizer's connecting jacks and special-purpose switches are located.

A.C. Power Switch

The AC switch on the back panel applies power to the Matrix-12 when turned ON - flipped downward - and will light up. It is recommended that the Matrix-12 be turned OFF when not in use.

A.C. Power Receptacle

The recessed 3-pong receptacle is used to connect the Matrix-12 with the AC power cord supplied with the Matrix-12 as a standard accessory.

Voltage Select Switch

The Matrix-12 is shipped from the factory set for either local A.C. power in the United States or Canada (the "115" setting which operates within the range of 95 to 130 volts, 50-60 cycles) or is set for European local power (the "230" setting which has a range of 200 to 240 volts, 50-60 cycles). The recessed Voltage Selector switch adjacent to the AC Receptacle is used to select either 115V or 230C line level voltage.


When enabled (switched ON), the MEMORY PROTECT prohibits storing anything into memory. This prevents the accidental changing or erasure of your patches for the entire synthesizer. In order to use the STORE button to program patches or use the Cassette Interface to load patch information into the Matrix-12, MEMORY PROTECT must be disabled (switched OFF).

MIDI Memory Protect

The MEMORY PROTECT feature of the Matrix-12 also includes incoming data transfers via MIDI. If incoming MIDI data is received when the unit's Memory Protect switch is ON, the Upper PAGE MODIFIER display will show the message...


...briefly and the Matrix-12 will ignore the rest of the incoming data.

MIDI Ports

The Matrix-12 utilizes the universally accepted MIDI interface system and employs the three MIDI jacks - IN, OUT and THRU - that permits the synthesizer to be interfaced with other devices (another synth, drum machine, sequencer computer, etc.) equipped with MIDI.

MIDI OUT is used when the Matrix-12 is intended to be used as the Master, controlling another synthesizer or MIDI instrument.

MIDI IN is used when the Matrix-12 is being controlled as a Slave by another MIDI instrument or controller.

MIDI THRU makes it possible to connect up to five* MIDI instruments in a "chain" by passing MIDI data information along from one instrument to another that originates from the Master.

*The recommended limit of five instruments is assuming that you are not using very long MIDI cables (maximum total length for the entire rig is about 50'), all of the instruments have been designed to conform to the MIDI Specification and the components of the MIDI circuitry of each instrument - especially the optoisolators - are not malfunctioning.

CASSETTE Interface

Once you begin to program your own original patches, you will find that you can very easily create more patches than the Matrix-12 has room for in its own internal memory. The CASSETTE Interface feature allows you to "offload", or record these patches in their digital form (called "data"), on standard cassette tape. You can then begin to program a second set of patches, offload them onto cassette, do a thrid set and so on until you have built up a library of sounds.

TO - This jack is used to connect the Matrix-12 to your cassette recorder's input jack which can be either its AUX or MIC. This permits patch data from the synthesizer to be outputted and recorded onto the tape.

FROM - This jack is used to connect the Matrix-12 to your cassette recorder's output jack which can be either its EARPHONE, HEADPHONE, or EXTERNAL SPEAKER jack. This permits the patch data information on the tape to be loaded back into the synthesizer. The recorder's LINE OUT jack is not recommended for this purpose.

The procedure for using the CASSETTE Interface feature to save and load patches, as well as how you can also use MIDI to do this, is covered in the MASTER PAGE section later in the manual.


This is the input used when the Matrix-12's Envelopes, LFOs or Ramps are programmed to respond from External Trigger (EXTRIG).The polarity is switchable from the Matrix-12's front panel. The ideal trigger pulse to use is 1ms (millisecond) in duration and between +5 and +10 Volts DC.


The Matrix-12 is capable of being controlled by two footpedals for common functions such as volume control and sustain as well as many other unusual functions that we will cover later. These pedals are connected to the synthesizer by the PEDAL 1 & PEDAL 2 input jacks on the back panel. Their polarities can be switched from the front panel.

PEDAL 1 & 2 may be used with a 'continuous" pedal - a rocker-type pedal usually used for volume or filter control. As we talk about the Matrix-12's modulation capability in a later section, you will discover how you can also toute the pedal's control to the VCO's, for example, to get pitch bend, to the LFO's for vibrato amnount, and to many other "destinations" as they are called to achieve enormous flexibility in footpedal control.

PEDAL 1 & 2 may also be used with a "switch" pedal - an on/off type pedal usually used for sustain. As with PEDAL 1, this pedal's control can also be used to perform other functions as well.


This port is used to connect a footswitch to the Matrix-12 that will be used to advance Patches or the Patch List programmed in the CHAIN Page. If you are usign a trigger to advance through the Patch progams, the Matrix-12 is progammed to respond to a rising edge (positive)trigger. This polarity is not changeable.


These ports are the Matrix-12's main outputs that you connect to a mixing console, amplifier and speaker system. The LEFT and RIGHT jacks are true stereo outputs and Voice Panning is controlled from the front panel displays. When MONO is used, all Voices will be output from this jack regardless of its panning assignment. However, any Voice panned OFF will be removed from these mixed outputs altogether.

The Matrix-12 may also be updated with an optional update kit that adds 12 individual Voice outputs that provides a separate audio out jack for each Voice. Contact your nearest ECC/Oberheim Authorized Service Center for prices and availability.


The "AUDIO OUT" LEFT, MONO and RIGHT jacks, the PEDAL 1 and PEDAL 2 jacks all require a standard "guitar cord" when using them. A guitar cord is simply a 2-conductor shielded cable with a 1/4" plug on the end that plugs into the Matrix-12.

The CASSETTE IN and OUT jacks require a 2-conductor sheilded cable with an 1/8" plug on the Matrix-12 end.

The MIDI IN, OUT and THRU jacks require a standard MIDI cable to be used properly.