Introduction
The 2x4 Audio Controller is a compact (1 rack space), comprehensive audio switching and control system designed to
interface a wide variety of effects and amplifiers. Easily configured for use with any type of system, the 2x4 can be the heart
of a simple pedal-based system, to a more elaborate line level “rack effects” rig, or any combination in between. The 2x4
consists of 8 series audio routing loops and 4 “footswitch type” Control Functions, 2 of which can be used as switchable
audio outputs (mutes). These 12 functions are MIDI controlled via control change numbers, and can be interfaced with a
number of different control devices. Of course, the 2x4 is best suited for use with the CAE RS-10 MIDI Foot Controllers. The
RS-10MKII is a perfect companion for the 2x4 and is fitted with a rugged XLR connector, as is the 2x4, for reliable, easy
interfacing. The 2x4 Audio Controller utilizes passive relay based switching in it’s signal path for the upmost sonic transparency.
In addition, unlike other relay based switchers, the 2x4 uses 2 separate relays for each loop; 1 for the send, and 1 for the
return. This eliminates any high gain crosstalk and/or oscillations when using preamps or fuzz pedals in the loops, resulting in
quieter, more predictable operation. Switching noise is also kept to a minimum. The 2x4 consists of 2 series chains (A&B) of
4 loops each. The inputs and outputs of both chains are accessible on both the front and rear panels of the 2x4, the front
panel inputs having priority over the rear. The input of each chain contains a low noise signal buffer to eliminate signal loss
when feeding the chains with high impedance signal sources such as passive guitars. Both buffers can be hard-wire bypassed
on the front panel for a completely passive signal path. The loop sends and returns are located on the rear panel of the unit
as is the MIDI In, Out/Thru and 9vac power input. The front panel also contains the Control Function jacks as well as the
switchable audio outputs. In addition, there are LED’s to indicate Loop/Control Function status and power. As mentioned
before, the front panel also utilizes an XLR connector for interfacing CAE RS-10 MIDI Foot Controllers.
Connecting the 2x4
Typical effects devices, either of the pedal type or “rack mount”, connect to the rear panel send/return jacks. Effect inputs to
the loop sends, effect outputs to the returns. An exception is when using a Chain (or part of a Chain) as a switchable splitter.
In this case, effects and/or amp inputs connect to the sends, and no connection is made to the returns. See example diagrams
for details. Amps and preamps, as well as any device using the Control Functions connect to the front panel. However, since
there is access to both Chain A&B inputs and outputs on the rear panel as well as the front, connections between the loops
can take place in front or on the rear of the unit. Connect MIDI controllers to the rear panel MIDI In or if you are using a CAE
RS-10, to the front panel XLR. The 2x4 will provide phantom power to the RS-10 Foot Controller when using the front panel
XLR or the rear panel DIN connector. See connection diagrams and front/rear panel descriptions for more details.
MIDI Control of the 2x4
The 2x4 Audio Controller responds to MIDI control change data in Omni mode (all channels). Each loop and Control Function
is assigned a separate MIDI control number. These numbers are fixed at the factory and cannot be changed except by
software revision. Care must be taken when using multiple 2x4’s in a system so that 2 or more units do not respond to the
same MIDI control numbers. Therefore, each 2x4 is capable of responding to 2 different sets of control numbers depending
on the addition (or deletion) of circuit board jumper J2. In most cases, this procedure will not be needed. Please consult the
factory if the alternate set of control numbers are necessary. The 2x4 responds to MIDI control data as follows:
MIDI control value 000 = Loop “Out”; Control Function = Open; LED indicator “off”.
MIDI control value 127 = Loop “In”; Control Function = Closed; LED indicator “on”.
The 2x4 Loops/Control Functions and their respective MIDI control numbers are as follows:
Normal Control Numbers Alternate Control Numbers
Chain A Loop 1 = Control #1 Chain A Loop 1 = Control #101
Chain A Loop 2 = Control #2 Chain A Loop 2 = Control #102
Chain A Loop 3 = Control #3 Chain A Loop 3 = Control #103
Chain A Loop 4 = Control #4 Chain A Loop 4 = Control #104
Chain B Loop 1 = Control #5 Chain B Loop 1 = Control #105
Chain B Loop 2 = Control #6 Chain B Loop 2 = Control #106
Chain B Loop 3 = Control #7 Chain B Loop 3 = Control #107
Chain B Loop 4 = Control #8 Chain B Loop 4 = Control #108
Ctrl. Function 1/Out 1 = Control #9 Ctrl. Function 1/Out 1 = Control #109
Ctrl. Function 2/Out 2 = Control #10 Ctrl. Function 2/Out 2 = Control #110
Ctrl. Function 3 = Control #11 Ctrl. Function 3 = Control #111
Ctrl. Function 4 = Control #12 Ctrl. Function 4 = Control #112
