Specifications

Bosch Security Systems | 2007-08 | 9922 141 50672en
Plena Loop Amplifier | Installation and User Instructions | Design and planning en | 18
2.4 Potential problems
2.4.1 Metal loss
New buildings often contain a large amount of metal
(for example, meshes in concrete floors and ceilings).
The metal will have an effect on the high frequencies of
the signal. You can adjust the tone of the audio signal on
the induction loops with the Metal loss compensation
control on the rear of the loop amplifier (refer to
section 5.3). The metal loss compensation is a variable,
signal dependent addition of high frequencies.
2.4.2 Overspill
The larger the induction loops, the more overspill.
When there is overspill, people outside the room with
the induction loop system can overhear the audio signal
on the induction loop. Overspill can also cause
interference on other induction loop systems in the
same building.
When you design a quadrature system (refer to
section 2.2.2 and section 2.2.3) or a low-spill system
(refer to section 2.2.4), you can avoid large induction
loops and thus avoid the potential problem of overspill.
2.4.3 Earth loops
Earth loops can cause interference on the induction loop
system. You can avoid earth loops when you connect
the shielding of cables only to one device.