Ritron LPA-V150, Руководство пользователя

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2.4
LPA-Series 600
Ω
BALANCED installation
The LPA-Series receiver can be connected to the 600
Ω
balanced MIC INPUT of
a public address amplifier when the LPA receiver is not located close to the PA
amplifier.
•
When an LPA radio message is received, the LPA receiver will send the audio to the 600
Ω
microphone input
of the PA amplifier.
•
A typical balanced cable contains two identical wires, which are twisted together and then wrapped with a third
conductor (foil or braid) that acts as a shield. The wires are twisted together, to reduce interference from
electromagnetic induction. Twisting makes the loop area between the conductors as small as possible, and
ensures that a magnetic field that passes equally through adjacent loops will induce equal but opposite
currents, which cancel out. The separate shield of a balanced audio connection also yields a noise rejection
advantage over an unbalanced two-conductor arrangement (such as AUX IN) where the shield must also act
as the signal return wire. Any noise currents induced into a balanced audio shield will not therefore be directly
modulated onto the signal, whereas in a two-conductor system they will be. This also prevents ground loop
problems, by separating the shield/chassis from signal ground.
NOTE: To minimize noise it is often necessary to connect the ground shield at only one end of the cable.
Section 2
Installation 10
LPA PA Amp
HOT connects to HOT or “ + ” or POS
COLD connects to COLD or “ - “ or NEG or COM
GND connects to GND or CHASSIS or
600
Ω
MIC-1
PUBLIC ADDRESS AMPLIFIER
GND COM HOT
600
Ω
MIC-2 SPEAKER
AUX INPU
COM 4
Ω
8
Ω
16
Ω
COM 25V 70V
T
L R
UNSWITCHED
SHIELDED,
TWISTED PAIR
L R
AUX IN
HOT GND COLD
600
Ω
BALANCED
L R
AUX OUT
LPA-SERIES RECEIVER