Sennheiser SI 30 General Description page 3

SI 30/SZI 30
IR Audio Transmission Technology |
1 LED indicator for transmission mode
2 11 IR transmission diodes
SI 30 front panel
1 AF input (3-pin Texas socket)
2 Channel switch (stereo, channel 1, channel 2)
3 RF output (3.5 mm mono jack)
4 Power supply socket (2-pin Texas)
SI 30 back panel
Texas
connector
Connector assignment in stereo operation
Texas
connector
Connector assignment in single-channel operation
1 2
1 2 3 4
3.5 mm
stereo jack
ground
AF + right channel
AF + left channel
3.5 mm
stereo jack
ground
not assigned
AF signal
Modulators/Radiators
SI 30 Modulator/Radiator
The SI 30 is a miniature combination modulator/radiator. It is slim and compact but
can cover areas of up to 80 m
stereo wideband modulation. When the audio signal at the SI 30 input exceeds a
certain threshold value, the modulator/radiator is switched on automatically. It
switches off again when there has not been an audio signal for about 2 minutes.
Transmission is indicated by a green LED on the left of the front panel.
The radiator of the SI 30 comprises 11 IR transmission diodes connected in series.
The AF input of the SI 30 is a 3-pin Texas socket located at the back of the unit, on
the left. It is an unbalanced stereo input, so you should not use long connection
cables. A 2 m connection cable with 3.5 mm stereo jack to a 3-pole Texas connector
is supplied as standard.
An automatic modulation control adapts to audio signals between 45 mV and 4 V.
This process is effected over a period of about one minute, so that short speaking
pauses do not entail a greater amplification. Problems may arise when you are work-
ing with microphones and very different signal levels. Longer breaks can lead to a
strong increase in amplification.
When connecting the SI 30 to headphone sockets of TV sets or similar sound sources,
you should adjust the level to a medium value. Too low a level results in more noise.
With the channel selector switch, you can choose between channel 1 or 2 trans-
mission or stereo operation. In mono operation, the integrated radiator and all
connected radiators can cover a greater area. For mono transmission, choose the
frequency suitable for the receiver, e.g. 2.3 MHz (channel 1) for the RI 150.
The RF output for connection of additional radiators is designed as a 3.5 mm mono
jack socket. You can connect both SZI 30 mini radiators or high-power radiators such
as the SZI 1029. For short distances, you can use connection cables from the Senn-
heiser accessory range. When working with greater cable lengths, you can make
your own cables using standard 50-Ω RG 58 co-axial cable.
The NT 20 plug-in mains unit is connected to a 2-pin socket at the back of the SI 30.
For supplying clusters, e.g. one SI 30 modulator/radiator and two SZI 30 radiators,
you can use the NT 20-4 plug-in mains unit and a KKY 20-015 4-way "octopus"
cable for connection. They have been designed for up to four SI 30 / SZI 30 units.
2 in mono operation. The integrated modulator uses