fall below the minimum load impedance which may lead to
overload of the amplifier.
For connection of the loop cable, twist the cable section
between the amplifier and the loop, if possible, and connect
the two stripped cable ends to the terminals LOOP (11).
Pay attention to a good contact so that no interfering con-
tact resistance will result. When laying the cable, avoid any
connection to earthing if the insulation is damaged.
4.3 Microphones
Connect a microphone for transmission of the ambient
noise and words spoken in the room to the 6.3 mm jack
MIC (14). An electret condenser microphone (e. g. ECM-
300LA from MONACOR especially designed for this appli-
cation) is recommended. This may e. g. be placed on a
table from where it picks up ambient noise and telephone
ringing best. The supply voltage required by this micro-
phone is made available via the tip contact of the connec-
tion jack (7.2 V
via 2 kΩ).
Dynamic microphones are not suitable because of the
susceptibility to feedback due to their electromagnetic op -
erational system.
4.4 Units with line level
Connect an audio source with line output (e. g. TV set, CD
player, cassette recorder) to the phono jacks LINE IN (13).
For connection of a TV set, the supplied cable may be
used.
4.5 Signal sound
A signal sound created in the unit may be released via a
switch or momentary pushbutton (e. g. in the form of a bell
knob) connected to the terminals ALERT (12). As long as
the contacts are connected, the sound can be heard.
4.6 Power supply
Finally connect the low voltage plug of the power supply unit
to the jack 12 V~/1.5 A (10) and the power supply unit to a
mains socket. With the connection of the power supply unit
the amplifier is switched on; the power indicator ON (8) lights
up. To switch the unit on and off conveniently, it is recom-
mended to use a switchable mains socket or a master-slave
socket rail which allows to switch the LA-40 automatically
with the TV set.
GB
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