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CHAPTER 2: AMPLIFICATION AND AUDIO
The UPM-1P and UPM-2P loudspeakers use sophisticat-
ed amplification and protection circuitry to produce con-
sistent and predictable results in any system design. This
chapter will help you understand and harness the power
of the UPM-1P and UPM-2P amplifier and audio systems.
The user panel of the loudspeaker (Figure 2.1) provides two
slots for modules. The top slot contains the audio input
module. The optional RMS communications module sits in
the bottom slot if installed; a blank plate covers the bottom
slot if RMS is not installed.
Figure 2.1. The user panel of the UPM-1P with standard looping
audio input module and optional RMS
NOTE:
See Chapter 3, "RMS Remote Moni-
toring System (Optional)," for more informa-
tion on using RMS with the UPM-1P and UPM-2P
loudspeakers.
AUDIO INPUT
UPM-1P and UPM-2P loudspeakers use a balanced,
female XLR connector for the audio input module in the
loudspeaker, and a male XLR loop connector to inter-
connect multiple cabinets. The loop connector, wired in
parallel to the audio input, transmits the input signal if the
loudspeaker is turned off for any reason.
The audio input presents a 10 kOhm balanced input im-
pedance to a three-pin XLR connector with the following
connectors:
■ Pin 1 — 220 kOhm to chassis and earth ground (ESD
clamped)
■ Pin 2 — Signal ( + )
■ Pin 3 — Signal ( - )
■ Case — Earth (AC) ground and chassis
NOTE:
Ensure that all cabling carrying
signal to multiple loudspeakers is wired cor-
rectly (Pin 1 to Pin 1, Pin 2 to Pin 2, and so on), to
prevent the polarity from being reversed. If one or
more loudspeakers in a system has reversed polar-
ity, this can cause severe degradation in frequency
response and coverage.
CAUTION:
Shorting an input connector pin
!
to the case can form a ground loop and
cause hum.
Input Module Options
There are two interchangeable audio input modules with
and without controls for different applications.
Looping Audio Input Module
All UPM-1P and UPM-2P loudspeakers are equipped
standard with the looping audio input module (Figure 2.2),
Pins 2 and 3 carry the input as a differential signal; pin
2 is hot relative to pin 3, resulting in a positive pressure
wave when a positive signal is applied to pin 2. This input
module has a balanced, female XLR audio input connector
and a male XLR loop out connector.
GND
1
1
Circuit
2
2
3
3
220k
Case
Earth /
Chassis
Input
Loop
Figure 2.2. The looping audio input module
CHAPTER 2
Looping Audio Input
10k
Balanced
+
-
Limit
On / Temp.
9
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