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Bosch Security Systems | 2011-02
Praesideo 3.5 | Installation and User Instructions | 4 | Amplifiers en | 141
Often, for each rack of main amplifiers, one spare
amplifier is used. To connect multiple main amplifiers
of the same type to a spare amplifier of the same type:
• Connect the loudspeaker output of the spare
amplifier to the spare inputs of the first main
amplifier.
• Loop-through the spare inputs of the first main
amplifier to the spare inputs of the other main
amplifiers. Please note that if the number of failing
main power amplifier increases, the loudspeaker
load of the spare power amplifier increases. This can
result in an overload of the power amplifier. Also
note that the audio distributed to the loudspeaker
lines of all failing power amplifiers depends on the
configuration settings of the first failing power
amplifier, since only the configuration settings of the
first failing power amplifier are transferred to the
spare power amplifier.
8.3.6 Connecting audio inputs
The number of audio inputs depends on the type of
power amplifier.
The audio inputs are used to interface with analog audio
sources. Each audio input is selectable between line and
microphone.
It is possible to connect unbalanced signal as well as
balanced signals. Unbalanced signals can be connected
to the 0 (GND) and the + or - pins (see figure 8.10). The
remaining, non-connected pin do not have to be
connected to the 0 pin. A balanced signal should be
connected between the + and - pins of the audio input.
The 0 (GND) pin can be connected to the shielding of
the signal cable. However, this is not required.
figure 8.9: Power amplifier, after spare switching
100 V
70 V
Spare In +
Lsp Out +
50 V
0 V
Spare In -
Lsp Out -
50 V
100 V
70 V
Spare In +
Lsp Out +
50 V
0 V
Spare In -
Lsp Out -
50 V
1
2
table 8.6: Number of audio inputs
Type Audio inputs
PRS-1P500 2
PRS-2P250 2
PRS-4P125 2
LBB4428/00 4
figure 8.10: Audio input connectors
12
0
Audio In
0