Installation Recommendations - I-AMP GPT 60-IV User Manual

amplifier. With the internal 2:1 compressor the typical dynamic range will be reduced, reducing the peak
current requirements.
Peak current requirement (AMPS)
This can be used as a guide to the installation requirements, however the field strength meter should be used
to set the final current through the induction loop.

INSTALLATION RECOMMENDATIONS

The induction loop produces a base-band audio magnetic field in the pick-up area. As such it can interfere
with the operation of dynamic microphones and cause feedback in the induction loop and any speakers
sourced from the same microphone. It is therefore recommended that condensor type microphones be used
in the induction loop pick-up area.
Dynamic microphones vary in their effective shielding from base band magnetic fields. This variation also
gives rise to a variation in the headroom to feedback of any system using a dynamic microphone in close
proximity to the induction loop.
The induction loop may be placed at floor level or above. The loop may be routed around small obstacles in
the pick-up area (such as doors and window, etc.) without significant changes to the generated magnetic
field.
Practical Constraints on Induction Loop Systems:
Not all installations are suitable for induction loop systems.
Induction loop systems should not be used where confidentiality is required unless the listening area is very
small. The low spill over systems described below are more concerned with reducing adjacent areas from
interfering with each other rather than increasing confidentiality.
High levels of background noise can be costly or impossible to reduce. Shielding or relocation of the
offending equipment or cables can be impractical. In these cases one of the other available assisted listening
systems should be used. This could include infra red or AM/FM systems.
The noise can be considered too high if the required signal to noise ratio cannot be met. The required signal
to noise ratio will depend on the application and should have a minimum value of between 25dB and 45dB.
The signal to noise ratio can be further improved by increasing the field strength in the area by increasing
the output level of the induction loop power amplifier. Australian Standard AS 60188.4 allows for deviations
from the standard value of field intensity in the event of magnetic background noise. Note that this is done
~ 10 ~
G p t 6 0 - I v
Length of one side of a square pick-up area ÷ 2.5
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