PLANNING AN INDUCTION LOOP SYSTEM - HINTS & TIPS
Induction loop system design and installation can be simple provided that a few basic
facts are understood. To help avoid poor performance and the need to re-position the
amplifier or loop cable at a later stage, we strongly recommend you refer to the infor-
mation below and the example layout diagram(s) provided in our seperate kit specific
Quick Start installation guides.
Maximum area coverage
The approximate coverage provided by the VL1 amplifier using the TX2 pre-formed
loop (as supplied in all VL1 range kits) is 1.2m
2
to 1.5m
2
.
Loop cable position
The TX2 loop can be positioned either horizontally or vertically. In all instances, the
exact position of the loop will depend on the application and the area requiring cover-
age - refer to the Quick Start installation guide supplied with your VL1 kit for further
information.
Always run a trial loop and test to evaluate performance and coverage by listening to
the signal with either a hearing aid or a dedicated loop test receiver. When you are
happy with the quality and coverage of the loop field, the loop should be secured into
position using a fixing method appropriate to the application.
Overspill and ‘cross-talk’
The signal generated by the loop will radiate outside as well as inside the loop. If
there are any other loop systems in close proximity, overspill such as this may lead to
‘cross-talk’ (signals from different loops merging into one). If this is likely to be an
issue, special designs of loop can be implemented to help reduce the overspill field -
contact your supplier for details.
Applications with high metal content
Large amounts of metal can affect the strength of the loop field and result in a
“muffled” sound being generated. The VL1 includes a metal compensation control
that can help combat such problems - see page 7 for further details.
Mounting the amplifier
The amplifier is designed to be permanently mounted using the mounting holes pro-
vided and 2 x No. 8 japanned woodscrews. Fix the amplifier securely to the chosen
surface taking note of the Safety Precautions on page 2 of this manual. The stated
screws will be suitable for most applications. However, always assess the condition and
construction of the mounting surface prior to installation and use an alternative screw
fixing if necessary.
Microphone position
Position the AMT microphone (as supplied in VL1/C,VL1/B1 and VL1/B2 kits) as close as
possible to mouth height using the self-adhesive pad supplied. For optimum perform-
ance it should be located no nearer than 300mm and no further than 1.2m away from
the operator’s mouth. If an alternative microphone is used, it must be an ‘electret’ and
not a ‘dynamic’ microphone.
Approved document No. DCM0003479 Rev 1 • Page 5 of 8
Summary of Contents for VL1
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