Mackie Sound Palette SP2400 Instruction Manual - page 20
SP2400 – 20
Using the AMBIENT MIC
The ambient mic is an optional accessory (MT-
3100) that is available for the SP2400, 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.
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 SP2400, 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.
Adjust the ambient mic preamp gain trim (located just
above the ambient mic connector on the rear panel,
through the unmarked hole) 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 Proce-
dure (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 SP2400, 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 and B is provided for
each 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 +40dB 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 +40dB switch to the up position (for a line-
level signal only).