Specifications

Bosch Security Systems | 2007-08 | 9922 141 50672en
Plena Loop Amplifier | Installation and User Instructions | System overview en | 9
1 System overview
1.1 Loop amplifier
The PLN-1LA10 Plena Loop Amplifier has been
designed as a very high-quality amplifier for medium to
large size induction loop systems. Ease of installation
and use have been major factors in the design,
combined with optimized performance.
1.2 Induction loop systems
1.2.1 Introduction
An induction loop system consists of a looped wire that
is installed along the walls of a room and a loop
amplifier.
1.2.2 Principle
The loop amplifier changes incoming audio signals in
an alternating electric current that is sent through the
induction loop. The strength and frequency of the
electric current varies with the tone and the amplitude
of the incoming audio signal and generates an
alternating magnetic field inside the induction loop.
People with assistive listening devices who are located
inside the induction loop, can put their assistive listening
devices in the T or MT mode to listen to the audio
signals.
In the T or MT mode, a little coil is activated (T stands
for ‘tele-coil’). The coil receives the alternating magnetic
field and changes it into an alternating voltage, which
the assistive listening devices change into an audio
signal. This audio signal is not entirely the same as the
incoming audio signal of the loop amplifier, because the
assistive listening devices also compensate for individual
hearing disabilities (for example, signal strength and
frequency range).
figure 1.1: Plena Loop Amplifier
table 1.1: Performance
Frequency response:
60 Hz to 10 kHz (+1/-3 dB, @ -10 dB @ rated output
Distortion:
< 1% @ rated output, 1 kHz
Bass control:
-8/+8 dB @ 100 Hz
Treble control:
-8/+8 dB @ 10 kHz
table 1.2: Certifications and approvals
EMC emission:
acc. to EN55103-1
EMC immunity:
acc. to EN55103-2
Safety:
acc. to EN60065
Induction loop systems:
acc. to EN60118-4
acc. to IEC118-4
figure 1.2: Assistive listening device
table 1.3: Assistive listening device
No. Description
1 Tele-coil
2 Microphone
3 Gain control
4 Amplifier
5 Earphone
T/MT
12 3 5
4