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SP1200 – 19
Using the Paging Mic
The paging mic is used to make announcements
over the system. If the paging mic is a condenser
mic or other type of mic that requires phantom
power, move the
PHANTOM
switches to the down
position. Otherwise, leave them switched up.
The paging mic can be voice-activated and is
routed to all channels or zones. However, you have
the option of activating it manually with an external
switch. If you choose to use a switch for the paging
mic, you have the additional option of assigning the
paging mic to either Zone A or to all zones (if multiple
SP1200s are used).
• For Zone A only, connect a (normally-open)
switch between the
ZONE A
and
GROUND
pins on
the
PAGING MIC CONTROL
connector.
• For all zones in a system interconnected via the
EXPANSION
bus, connect a switch between the
ALL CALL
and
GROUND
pins on the
PAGING MIC
CONTROL
connector.
• For maximum flexibility, connect two switches
to the
PAGING MIC CONTROL
connector and have
both selections available.
The paging mic can be configured to automatically
turn down (duck, or attenuate) the music that is
playing over the system so the announcement can
be heard when using the VOX circuit. When an
announcement is over, the music gradually returns
to its original volume.
The music ducks fairly rapidly, attenuating the
music 20 dB within 300 ms (milliseconds) of
detecting a signal on the paging mic. When the
signal on the paging mic stops, there is a 1500 ms
(1.5 second) timeout period to make sure the
announcement is over, and then the music ramps
up to its original volume over the next 2.5 seconds.
Note 1: When manually activating the paging mic,
there is no timeout period after the announcement
ends. The moment you let go of the switch, the
music begins to ramp up to its original volume.
Note 2: When the manual switch is off, the
voice-activated (
VOX
) control for the paging mic is
still operational. Ensure that the
PAGING MIC VOX
threshold is set accordingly to prevent false
triggering of the paging mic input when using
PAGING MIC CONTROL
switching. Alternatively,
turn the
PAGING MIC VOX
control all the way up
(fully clockwise) to defeat the VOX circuit. Note that
each zone has its own
PAGING MIC VOX
control.
Setting the GAIN
When a microphone is connected directly to the
paging mic input, the
GAIN +40 dB
switch should be
set in the down position (for a mic-level signal). When
the paging mic is going through an external mixer,
sending a line-level signal to the paging mic input,
move the
GAIN +40 dB
switch to the up position (for
a line-level signal only).
Adjust the
MASTER VOLUME
control by
pressing the up/down buttons so the meter
indicates a level at the “
0
” mark. With all music
sources off, speak into the paging mic with a
normal voice. Adjust the
PAGING MIC GAIN
control
with a non-conductive alignment tool so that the
meter indication is near the “
0
” mark. This provides
the best signal-to-noise ratio for the mic, and
insures that the signal from the paging mic is strong
enough to trigger the
VOX
circuit.
Setting the VOX Threshold
This control determines how strong the signal
from the paging mic must be to trigger the
VOX
circuit, which ducks the program source when an
announcement is made. Ideally, the threshold
should be set so it is sensitive enough to trigger the
VOX
circuit as soon as you begin speaking, but not
so sensitive as to be triggered by ambient sounds
around the microphone. Set the
PAGING MIC VOX
control to the center position with a non-conductive
alignment tool to start. Turn the control counter-
clockwise to lower the threshold (increase the
sensitivity) if the beginning of announcements are
getting clipped off. Turn the control clockwise to
increase the threshold (decrease the sensitivity)
should you experience false triggering due to
ambient noise around the microphone.
Using the EQ
The paging mic has a 2-band equalizer for
adjusting the lows or highs on the microphone
signal. When the controls are set to “
U
” (unity), the
EQ has no effect on the signal.
Using the Ambient Mic
The ambient mic is an optional accessory (MT-
3100) that is available for the SP1200, which is used
to sense the ambient noise level in the room. Set
the
AMP ADDRESS
switch #8 up to enable the
ambient mic, otherwise leave the switch down.
The ambient mic provides an “ear” for the micro-
processor to gauge the ambient noise in the room and
adjust the gain of the paging mic accordingly. When
the background noise is relatively quiet, the paging
mic gain is at its lowest level. If the background
noise is relatively loud, the paging mic gain is at its
highest level. If the background noise is some-
where in between, the paging mic gain is midway
between its lowest and highest preset levels.