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Adjusting the sound
The TS-150 is set up for a flat frequency curve when supplied. Normally it is not
necessary to change the base or treble setting on the loop amplifier, as this is ad-
justed in the hearing instrument. If required, however, these may be adjusted with
the trim potentiometer TONE.
AGC or not?
The amplifier has an automatic gain control (AGC). It should ensure that the signals
from the sound sources are kept within an acceptable level and prevent the signals on
the loop becoming too strong or too weak. If the signals from the sound sources come
from extra loudspeaker outputs, it is important to activate this function. If the signals to
the TS-150 come from Scart, audio or line outputs, the AGC function is not necessary
and can be switched off. Most hearing instruments have the AGC function connected
in constantly to prevent the sound from the loop system becoming too loud for the ear.
Adjusting the loop current (GAIN)
To ensure good sound quality in the hearing instrument, it is important for the field
strength to be correct and to comply with the requirements of the international stand-
ard IEC60118-4 (see Note 2 on the next page). The field strength depends on factors
such as the loop current and must be adapted to the size of the room and its construc-
tion material. So it is important for the installation to be carried out correctly with
the aid of a field-strength meter.
Switch on one of your sources and select a program with voice or music.
a. Adjust the GAIN clockwise until the green LOOP CURRENT lamp lights up.
b. Place the field-strength meter centrally in the loop (room) about 1.2 m above
the floor and adjust the GAIN until the deflection of the field-strength meter
oscillates around 0 dB. The oscillation should follow the signal from the sound
source. The loudest parts of the speech/music should produce a deflection of up
to +12 dB on the meter.
c. Listen to the sound quality via the earphones of the field-strength meter or via a
loop receiver (e.g. Companion).
d. The user should now check the settings and evaluate the sound. The hearing instru-
ment is placed in the T-position. During this evaluation, the user should sit on a
chair in the centre of the room. When the system is correctly installed, the sound level
in the hearing instrument should be about equally strong from the inductive loop as
from a person speaking at a distance of about 80 cm. It should not be necessary to adjust
the sound level on the hearing instrument when changing its position from M to T.
ENGLISH
