Phonic PX2300, User Manual

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2. INSTALLATION
2.1 RACK MOUNTING
The Phonic PMX 2300 fits into standard rack, and takes one unit height of space (1 3/4"). Additional 4" depth
for the connectors on the back panel is needed. Be sure that there is enough air space around the unit for
cooling and please do not place the PMX 2300 in contact to or directly on top of high temperature devices such
as power amplifiers etc. to avoid overheating.
2.2 CONNECTORS
The PMX 2300 use XLR plug for microphone input, RCA plugs for BGM inputs, 1/4” phone plugs for emer-
gency audio input, utility output, zone 1/zone 2 outputs, an RJ45 plug for emergency override control, an
phonix 3-pin plug for remote level control, an D-Type 9-pin for source link, and an 3.5mm mini phone plug for
paging control.
2.2.1 Impedance
The microphone input impedance is less than 2k Ohms. As standard, the outputs of the PMX 2300 are elec-
tronically balanced with output impedance lower than 100 Ohms. When driving transformer coupled loads, it
may be necessary to create 600-Ohm source impedance. For this purpose, install two 247 Ohms resistors in
series with pin 2 and 3.
2.2.2 Unbalanced/Balanced Connection
Most of the mistakes in audio installations are incorrect and defective audio connections. In order to perfectly
complete your installation, please pay special attention to the following section unless you are already familiar
with balanced/unbalanced operation.
What is an unbalanced system?
You can find this system in most of home audio-video system. It gets one conductor to carry the signal, and the
other conductor for ground. Normally for lower level signal, the signal conductor is shielded by the ground
conductor.
What is a balanced system?
Balanced system transmits the signal via 2 conductors plus one ground shielding conductor. The 2 signal
conductors carry the same signal but out of phase. For the balanced input stage, the amplifier will boost the
difference of the 2 signal conductors and remove the identical part (known as common mode signal.) of the 2
signal conductors. Because of the real signal is carried by the 2 conductors out of phase, so it is perfectly
carried to the input. At the same time, the interference occurs during transmission will be identical part (common
mode), because the signal conductors are run together, there is no chance they can be different, and all the
interference will be removed by the balanced input amplifier.