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SP1200 – 20
Ambient Mic Calibration and Placement
1. Connect the MT-3100 (or other microphone) to the
AMBIENT MIC
connector on the rear panel. Make sure
the ambient mic switch is on (
AMP ADDRESS
switch
#8 up). Locate the ambient mic in an appropriate
position to pick up the ambient noise in the room. It
can be mounted on the ceiling or on a wall. Avoid
placing the ambient mic close to the speaker over
which the announcement is being made. Keep the
ambient mic away from a constant noise source, such
as a refrigerator or other mechanical device that emits
a continuous noise. The best placement is where the
mic can pick up an average representation of the
ambient noise level in the room.
Note: Each zone or channel must be calibrated
individually.
2. Turn off the SP1200, then turn it back on again while
pressing and holding the Input 2 button. This causes
the ambient mic preamp level to appear on the meter.
3. Establish the highest noise level that you would
expect to have in the room using a pink or white noise
source, or a music source. Input 1 is operational in this
mode to use as a music source, if desired.
4. The ambient mic preamp gain trim is located just
above the ambient mic connector on the rear panel,
through the unmarked hole. Adjust it with a non-
conductive alignment tool until all the green LEDs on
the meter are lit. Insure that no yellow or red LEDs are
lit, which runs the risk of clipping the ambient mic
preamp or ADC.
5. Press the “OFF” button when finished to return to
normal operation.
Paging Microphone Calibration
Procedure (When Used with Ambient Mic)
1. Perform the “Ambient Microphone Calibration
Procedure” described above.
2. Switch the ambient mic OFF (
AMP ADDRESS
switch
#8 down).
3. Adjust the
MASTER VOLUME
control by pressing the
Up/Down buttons so the meter indicates a level at the
“0” mark.
4. Adjust the
PAGING MIC GAIN
control as high as it will
go before feedback occurs while speaking into the
paging microphone.
5. Switch the ambient mic on (
AMP ADDRESS
switch
#8 up).
6. Turn off the SP1200, then turn it back on again while
pressing and holding the “3” button.
7. Release the Input 3 button after a few seconds and
the third LED starts flashing slowly.
8. Use the front panel Up/Down buttons to set the lower
level of the paging mic (how loud it is with very quiet
background noise). It should be loud enough to be
heard clearly throughout the coverage area.
9. Press the “OFF” button and the level is stored. The
third LED starts flashing faster.
10.Use the front panel Up/Down buttons to set the upper
level of the paging mic (how loud it is with very loud
background noise). As a general rule, set this level as
high as it will go before feedback (at the "0" mark if
steps 3-4 above were followed).
11.Press the Input 3 button when finished to store the
level and return to normal operation.
12.Verify that the paging microphone’s volume is sufficient
to be heard over the background noise in the room.
Note: For best results, with the background noise
level at a minimum, the paging mic volume should be
approximately the same as the music volume.
13.If the paging microphone is not loud enough to be
heard over the background noise, verify that the
ambient mic is properly placed to pick up an accurate
representation of the background noise. If it is, it may
be necessary to readjust the lower and upper levels
for the paging mic gain (steps 6-11).
Using the Local MIC/LINE INPUT
The
MIC/LINE INPUT A
is provided for the zone
to connect a microphone for a speaker in a
conference room, or similar sound reinforcement
applications. If the local mic is a condenser mic,
move the
PHANTOM
switches to the down position.
Setting the GAIN
When a microphone is connected directly to the
MIC/LINE INPUT
, the
GAIN +40 dB
switch should be
set in the down position (for a mic-level signal).
When the mic is going through an external mixer,
sending a line-level signal to the input, move the
GAIN +40 dB switch to the up position (for a line-
level signal only).
Press the
OFF
button to select the
MIC/LINE
INPUT
. 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 mic with a normal voice.
Adjust the
MIC/LINE INPUT 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 its relative volume will be equivalent to the
program sources.