Benefits; Plena; Block Diagram; Supervision - Bosch PLN-1LA10 Installation And User Instructions Manual

Security systems plena loop amplifier
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Plena Loop Amplifier | Installation and User Instructions | System overview


Ambient noise prevents hard-of-hearing people from
listening to a specific sound in a room. The ambient
noise can result from other people in the room,
equipment, but also from the acoustics. Depending on
the acoustics of the room, hard-of-hearing people
already find the reflected noise a strain when the
distance between them and the speaker is more than
2 m. The induction loop, to which the hard-of-hearing
people can listen with their assistive listening devices,
virtually reduces the distance to the speaker. Their
distance to the speaker seems equal to the distance
between the speaker and the microphone.


The Plena Loop Amplifier is part of the Plena product
range. Plena provides public address solutions for places
where people gather to work, worship, trade or simply
enjoy themselves. It is a family of system elements that
are combined to create public address systems tailored
for virtually any application. The range includes mixer,
pre, system and power amplifiers, a source unit, digital
message manager, feedback suppressor, conventional
and PC call stations, an 'All-in-One' system and a voice
alarm system. Each element is designed to complement
all others thanks to matched acoustical, electrical and
mechanical specifications.
Bosch Security Systems | 2005-05 | 9922 141 50672en

Block diagram

Refer to figure 1.4 for a block diagram of the Plena
Loop Amplifier.


All vital functions of the loop amplifier are supervised.
The loop amplifier checks its internal power amplifier,
the integrity of the connected induction loop and the
priority input with a pilot tone. When a supervised
function fails, a LED on the front panel of the loop
amplifier is lit and the fault contact is de-energized.

Quadrature system

One of the key features of the Plena Loop Amplifier is
that it can be used in quadrature systems. In a
quadrature system, an even number of Plena Loop
Amplifiers work together to create a magnetic field that
has the same strength throughout the whole covered
area and drops rapidly to zero beyond the borders of
the covered area. This is achieved by introducing a
phase difference of 90° in the electric current that flows
through two adjacent induction loops.
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