7. With the audio input source(s) active, increase the appropriate Level
control(s) until the red Limit indicator is just flashing occasionally.
TIP: If you are using the microphone and line input at the same time,
adjust both level controls to achieve an acceptable balance.
8. Adjust the Drive control until the red Peak indicator just lights during
periods of high signal level (i.e. when the red limit indicator just lights).
Warning: If the system is set up so the Peak indicator is permanently lit,
the audio sound quality will be distorted and the amplifier may shutdown
to protect it against overheating.
9. Using an induction loop test receiver, listen to the loop signal in
all areas where coverage is required. If the signal level is not
acceptable, adjust the Drive control in small increments until it is.
Note that when testing the installation, you may hear a slight
‘humming’ noise in the background. This IS NOT a fault with the
induction loop system but a common occurrence caused by mains
wiring. This hum will normally NOT be heard by hearing aid users
as most modern hearing aids have filters which cancel this noise
out.
10. If a large amount of metal is present in or near the induction loop, you
may find the sound you hear through the loop listening device is ‘woolly’
or ‘dull’. This is caused by the metal in the room absorbing the magnetic
field at a rate that increases with frequency, i.e. high notes are absorbed
more than low notes resulting in a ‘muffled’ sound. If this is a problem, try
turning the amplifier’s METAL COMP control clockwise in small increments
until a natural balance is achieved. Please note however that due to the metal absorb-
ing power from the amplifier, its area of coverage will be reduced and further reduced
as the METAL COMPENSATION control is turned clockwise.
11. For compliance with BS7594 (the code of practice for audio-frequency induction
loop systems), w
e recommend you test the system using our PDA RANGE FPROK1
induction loop test kit. Please contact your distributor for details.
Approved document No. DCM0003479 Rev
1
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