Oberheim Matrix-12 - Transmit; Pass

The Master controller that you are using to drive the MATRIX-12
must be set to transmit on the ZONE'S channel as well. The
exception to this (and this is an important one) is that if OMNI
MODE is turned ON in the ZONE, the MATRIX-12 will receive
Notes and Controllers on any MIDI channel for theVoices
assigned to that particular ZONE. The Master instrument can be
set to transmit on any MIDI Channel and its Notes and Controllers
will be received by the ZONE at all times when it is in OMNI
MODE. Patch Change commands are still received on the Basic
Channel and is not dependent on the ZONE'S channel setting.
TRANSMIT MIDI OUT
When MIDI OUT is used, the MATRIX-12 is considered the
Master in the MIDI system and handles MIDI communication the
same as when receiving. It will transmit its own Notes and
Controllers to other slaves in the system on the ZONEs1
channels. If OMNI is selected as a ZONE'S CHANNEL, notes
and controllers will be sent on the MATRIX-12's Basic Channel.
Patch Changes will be transmitted on the Basic Channel only.
If the MATRIX-12 is a Slave, MIDI OUT can still be used as well.
Playing notes on its Keyboard and using its controllers will
control another instrument as a Slave.
When the MATRIX-12 is a Slave, if MIDI OUT is used and MIDI
parameter ECHO is selected in the ENABLES Sub-Page, the
MATRIX-12 will transmit MIDI Notes and Controllers coming
from the Master controller as well as its own MIDI on whatever
you select as the channel settings for the active ZONES. If an
active ZONE has its CHANNEL parameter set to OMNI, Notes
and Controllers are transmitted on the MATRIX-12's Basic
Channel. Even though the MATRIX-12 is technically a Slave in
the system - due to the fact that its MIDI IN "slaves it" to the
Master controller- you can think of it as another Master when its
MIDI OUT and MIDI ECHO are used together.
Summary
If the CHANNEL of the ZONE that is being used to transmit is
set to OMNI, it will transmit Notes and Controllers on the
MATRIX-12's Basic Channel. If the ZONE is set to a single MIDI
Channel, that channel is the one used for transmitting and Patch
Change commands will still take place on the Basic Channel.
ECHO permits the combining of MIDI IN information plus the
MATRIX-12's own MIDI data and transmitting it via MIDI OUT.
PASS MIDI THRU
When the MATRIX-12 is Slaved and MIDI THRU is used instead
of MIDI OUT, it will only respond as a Slave in your MIDI system
and will simply pass information received from its MIDI IN to other
slave instruments in the system, unaffected by any MIDI
processing going on inside the MATRIX-12 itself. The
MATRIX-12 can still transmit information from its MIDI OUT port
but this information does not go out MIDI THRU -just the
information coming from the Master.
56 Matrix-12 Owner's Manual