The transmitter SI234 and the receiver HOl 234 form together an infrared'
system for the wireless transmission of stereophonic and two-channel
audio signals in HiFi-quality. An indication of this system's high quality is
given by its noise suppression system "HiOyn" which has brought about
a considerable improvement in the previously-attainable transmission
quality.ln order to ensure that it can still be used in conJunction with other
non "HiOyn" inlrared transmitters like,lor example, the SI434 and
SI405 the receiver HOl234 has been litted with a "HiOyn" ON/OFF
switch. The power radiated bythe mains-powered transmitter SI 234 is
sufficient for illuminating rooms 01approx. 24 m2in size. The "HiOyn"
compressor in the transmitter is not, unlike the corresponding »HiOyn"
expandor in the receiver HOl 234, litted with an ON/OFF switch. The
SI 234 can therefore only be used in conjunction with the HOl 234. The
universal connector litted to the end 01the transmitter's audio cable
ensures a problem-Iree connection to virtually all stereo ampliliers and
televisions with stereo sound. The signal emitted by the SI 234 is picked
up and reproduced by the battery-powered infrared receiver/headphone
HOl 234. The entire receiver circuitry as weil as the controls are built into
the ear pieces. The ring-shaped ear cushions and the softly padded
headband make these headphones very comfortable to wear over both
long and short periods 01time.
The system is put into operation as lollows:
Infrared transmitter SI 234
1. Plug the power supply unit 1 into a 220-V mains socket.
2. Insertthe connector 2into the headphone socket 01the stereo amplilier
resp. television set. In its entire lorm the universal connector will lit into a
6.3 mm jack socket. IIyour amplilier is fitted with a dice-5 socket you
merely have to remove the lorward section 01the connector inorder to
obtain the corresponding dice-5 plug. When putting the connector back
together one should ensure that the "PX 1" imprint and the connector's
cable outlet are both on the same side. IIthis is not the case, transmission
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will be in mono only. II in addition to the inlrared system you also wish to
connect a wire-bound headphone to your amplilier but only have one
connecting socket, the problem is easily solved by plugging itonto the
back contacts 01the universal connector.
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3. Position the inlrared transmitter so that the invisible infrared light is
radiated Ireely throughout the whole room. Oue to its Ilat construction
the transmitter will comlortably lit underneath or on top 01the rnajority of
ampliliers.
4. Switch on the transmitter 3. After switching on, the diode 4lights up
dimly. This diode serves as both ON/OFF- and modulation indicator and
lunctions as folIows: Sy turning the volume control on your amplifier you
will see that the diode lights up either brightly or dimly. The best-possible
modulation of the transrnitter has been achieved when the diode only
lights up brightly at peak volumes.
II it is continually bright, the transmitter is being overdriven. The other
extreme would be an "underrnodulation". This means thatthe transmitter
is not being sufficiently modulated - a sign 01this being that the diode
does not light up brightly, even at peak volumes. Under unlavourable
conditions this can lead to the occurrence of audible "hissing"
interference.
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