Signal Lamp Operation
The signal lamp button, when pressed, lights itself and all other signal lamps in stations on the
same communications circuit.
‘Sidetone’
Sidetone is simply the sound of your own voice, heard in your own ear, when referring to a headset or
telephone handset. You experience it every day when you use a telephone. When the LS3 is used in
its full duplex mode, we are expanding that definition to include the sound of your own voice, picked
up by the gooseneck microphone, and reproduced by the LS3’s loudspeaker.
Unlike ‘belt packs’ and headset stations, the sidetone control in an LS3 is automatic when a headset
or handset is connected to the unit. The recessed sidetone control (accessible through the front
panel) is only active when the station is being used in its full duplex hands-free mode, with a Gn'x'
gooseneck microphone plugged in. We strongly recommend a close-talking, noise-canceling
gooseneck microphone in this mode. Sidetone adjustment is critical to best performance. It is the
reduction of sidetone to near zero which allows the microphone and the loudspeaker to be active si-
multaneously without producing feedback. Before plugging in the gooseneck microphone, adjust the
volume to a comfortable level when listening to other stations. Next turn Off or disconnect all the other
stations in the system. Do not adjust the volume. Plug in the gooseneck microphone and switch the
Mic. switch to On. Adjust the sidetone control with a small screwdriver while tapping lightly on the mi-
crophone. The quietest position will be a ‘null point’ somewhere near the center of the control’s rota-
tion (near 12 o’clock).
Override Control Feature
LS3’s are equipped with a receive circuit which responds to a control tone generated elsewhere in the
system by an OG904 Override Generator module. An OG904 can be fitted into any Pro Intercom
station which can be used with a headset, handset, or microphone. This includes ‘belt packs’, head-
set stations, master stations, or other LS3’s. The override tone may be triggered by a separate switch
added to any of these devices, or by their microphone On/Off switch.
When the LS3 detects the control tone, it will switch to a predetermined mode, regardless of the posi-
tion of any of its front panel controls. The volume may be raised or lowered. The status may be
shunted from Off to Listen. The Talk function may be disabled.
Typical among applications for this feature are: restoring volume in a dressing room where the front
panel control has been turned down; muting a station when communications should not be heard at
that location, and; muting a second LS3 in a nearby location while the first is sending.
There are five modes of control, determined by the position of the recessed Override level control ac-
cessible through the front panel, and adding or removing links on the rear PC board.
Mode 0: No override function
Mode 1: Switch to preset override volume level
Mode 2: As mode 1, plus shunts Off/Listen/Talk from Off to Listen
Mode 3: As mode 1, plus shunts Off/Listen/Talk from any position to Listen.
Mode 4: As mode 1, plus shunts Off/Listen/Talk from Talk to Listen
As supplied from the factory, your LS3 is set for Mode 3.
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