About Your Induction Loop Amplifier - I-AMP GPT 60-IV User Manual

About your induction loop amplifier

The GPT 60-IV is an Industrial Induction Loop Amplifier designed to
drive current into a low impedance wire loop (the induction loop).
This current produces a base band electro-magnetic field which can
be received by the induction coil pickup in a hearing aid placed
within the loop area.
The amplifier features convection cooling (with no associated fan
noise) and an internal limiter that prevents the input signal from
extending the output to beyond the current capability of the GPT 60-
IV . Signal Presence and Current Output is indicted via the 6 level
LED meter on the front panel. An internal 2:1 compressor is used to
reduce the dynamic range of incoming audio, increasing
intelligibility to many hearing impaired.
The intensity and characteristics of the field produced by the current
passing through the loop is set by Australian standard AS 60188.4
These standards set the operating field strengths and frequency
response and the GPT 60-IV is designed to meet these requirements.
UN BA LA N C ED
IN PUT SUM M ER
+ 6 d B
+
+ 6 d B
-
BALAN C ED
IN PUT
PO WER SUPPLY
M AINS 2 4 0VA C
System Block Diagram
The voltage driving output of the GPT 60-IV has been designed to
accommodate the higher impedance of the induction loop as the
frequency is increased.
The GPT 60-IV is housed in a heavy duty standard 1RU rack mount
chassis. The unit is designed to be robust and reliable.
The GPT 60-IV is "Inherently Safe" and is designed to allow
continuous operation into a short circuit (0Ω) loop connection. This
provides greater reliability and simple loop design.
C O M PRESSO R SIG N A L
PRESEN C E
2 :1
LIM ITER
LO O P O UTPUT
+
-
PO WER
O N
LED O UTPUT
M ETER
~ 12 ~
G p t 6 0 - I v
FEATURES
Rear Panel:
All input and output connections via Phoenix
Stereo Unbalanced Inputs
Microphone Input with phantom power
Input Level Control
Output for induction loop connection via
screw terminals
Power On/Off switch
IEC Mains input power connection
Mains input fuse
Front Panel:
Indication of output current via 6 level LED
meter covering a range of 0dB to -21dB
Other:
Robust steel 1RU rack mount chassis
Power On indication
Output current, into low impedance
induction loop, of up to 4.5 Amps Peak
Input level adjustment range +6dB to -
Nominal input level +4dBu
Frequency response tailored to Australian
Standard AS 60188.4
Internal 2:1 compressor for dynamics
reduction
Internal fast limiter with typical clamp time
of 1ms to protect the amplifier from large
input signals
Large toroidal transformer for low
radiation, close to the front panel for easy
mounting
Convection cooled power amplifier with
rear facing heatsink
gpt
DESIGnS
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