Extended Functions - Monacor LA-75 Mode D'emploi

With a loop width of 4 m and a width-length ratio of
0.5, a peak current of 3 A results in the loop accord-
ing to fig. 7.
6) Adjust the optimum sound with the tone controls
BASS (7) and TREBLE (8).
5.2 Operation
The adjustments made under item 5.1 do not have to
be changed any more. The loop amplifier must only be
switched on for normal operation. The units of a PA
system should be switched on in the following order:
1. the audio units (signal sources)
2. the PA amplifier
3. the loop amplifier
To switch off the system, proceed in reverse order.

5.3 Extended functions

To use the following functions, the unit must be opened
which should be left to specialized personnel.
1) First switch off the unit and remove the screws on
the upper side as well as on the left and right sides
of the housing.
2) Remove the cover. The positions of the operating ele-
ments inside the unit are shown in fig. 8 on page 33.
3) After the adjustments have been made, replace the
cover, and screw it tightly.
5.3.1 Microphone priority circuit (talkover)
If an input signal e. g. an announcement is at channel
INPUT 1, the volume for channel INPUT 2 is automati-
cally reduced by approx. 40 dB when the function talk-
over is activated.
To activate the talkover function, place the jumper
JMP1 VOX in position ON.
5.3.2 Metal loss correction
Ceilings and floors of buildings frequently have a high
metal content. This metal may lead to a frequency-
depending loss of the field strength. The loss is
3 dB/octave with a lower limit frequency between
0.01 Hz and 100 Hz. The metal loss correction counter-
balances this by attenuating frequencies below 1 kHz
and boosting frequencies above this value up to
3 dB/octave.
The effect of the metal on the frequency response
can only be determined with special units requiring a lot
of effort. However, it is also possible to only monitor the
loop signal with an induction receiver (e. g. LR-200):
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1) To activate the correction function, place the jumper
JMP2 METAL LOSS in position ON and set the con-
trol METAL LOSS ADJ. to the left stop for the time
being and monitor the loop signal with an induction
receiver.
2) Adjust the control METAL LOSS ADJ. to optimum
speech intelligibility.
5.3.3 Siren volume
The volume of the siren tone can be adjusted.
1) Actuate the connected alarm switch or shortly
bridge the two alarm contacts (fig. 4) at the plug-in
screw terminals (11) and monitor the loop signal
with an induction receiver.
2) Adjust the control SIREN so that the volume of the
siren is in a useful ratio to the other audio signals.
6 Specifications
Max. loop current: . . . . . . 4.6 A
Admissible loop
resistance: . . . . . . . . . . . 0.2 – 0.5 Ω
Max. hearing area: . . . . . 75 m
Inputs (sensitivity/impedance, connection)
MIC: . . . . . . . . . . . . . . 2.9 mV/2 kΩ
LINE: . . . . . . . . . . . . . 660 mV/10 kΩ
Tone control
bass: . . . . . . . . . . . . . . 100 Hz, ±8 dB
treble: . . . . . . . . . . . . . 10 kHz, ±10 dB
Frequency range: . . . . . . 70 Hz – 7 000 Hz, ±3 dB
Power supply: . . . . . . . . . 12 V /5 A via low-voltage
Ambient temperature: . . . 0 – 40 °C
Dimensions
(W × H × D): . . . . . . . . . . 158 × 58 × 238 mm
Weight: . . . . . . . . . . . . . . 1.5 kg
Subject to technical modification.
2
6.3 mm jack, unbal.
phono, left/right
jack Ø 5.5 mm/Ø 2.1 mm
(outside/inside).
inside contact = positive
pole
GB
11