System Overview; Loop Amplifier; Induction Loop Systems; Introduction - Bosch PLN-1LA10 Installation And User Instructions Manual

Plena Loop Amplifier | Installation and User Instructions | System overview
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.
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
Bosch Security Systems | 2005-05 | 9922 141 50672en
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, the internal microphone of the
assistive listening devices is switched off and 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).
T/MT
1 2
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
en | 9
4
3 5