Ashly mXa-1502 12-Channel 4-Zone DSP Mixer-Amplifier User Manual
Page 21
Average Noise Meter
: This meter indicates
the average level of the selected ambient noise
detecting microphone.
ANC Setup Procedure
•
In software, place an ANC block on the
output channel to be used for background
music or voice paging in that zone.
•
Open the ANC block to edit its control
window. Set the ANC controls to the typical
settings described above, which are the
default settings of a new ANC block when it
is first placed.
•
Turn the ANC function ON.
•
Select the noise-sensing microphone input
from the drop-down box labeled "Mixer
Input Channel".
•
Physically locate the noise-sensing
microphone in the zone by pointing it toward
the primary noise sources such as groups of
people, HVAC equipment, vehicle traffic etc,
but pointed
away
from the sound system
speakers or their direct reflections.
•
Add appropriate mic preamp gain to the
ambient-sensing mic channel, add gain,
EQ, HPF or LPF, compression, or even a
noise gate if desired. The noise-detecting
microphone signal will appear on the
Average Noise input level meter. To adjust
ANC controls for good-sounding operation
without people present, a pink noise source
or even a portable stereo can be placed
near the expected ambient noise source to
simulate anticipated volumes.
•
Beginning at -40dBu, adjust the Noise
Threshold control to respond to the average
noise input level above which point you want
the program audio to begin increasing.
•
Increase the zone noise source volume until
you see the average noise meter rise above
your noise threshold setting. You should
begin to see the ANC Gain meter slowly rise
above the minimum gain setting.
•
Slowly increase the noise source further and
adjust the program/ambient gain ratio for
the desired amount of noise compensation.
•
Continue to increase the noise source
volume to the highest anticipated level.
Adjust the max gain to a level which limits
the maximum gain that the ANC applies to
the program audio so it will not become too
loud or clip.
•
The gain change rate can be adjusted
according to how fast you would like the
gain changes to take place in response to
changes in ambient noise.
•
Be aware that an improperly setup ANC can
result in runaway gain where the program
audio is picked-up by the noise-sensing
microphone as background noise. The
result is not necessarily feedback squeals,
but the gain of the program audio could
ramp up to the max gain value even with no
ambient room noise. The best remedy for
this problem is to locate the noise-sensing
microphone closer to the expected noise
sources and further away from the sound
system speakers or their reflections. A baffle
can be constructed between the speaker
and microphone to block direct or reflected
sound pickup. Also, the Program/Ambient
Gain Ratio can be lowered to reduce the
susceptibility to gain runaway.
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mXa-1502 • Operating Manual
Ashly AquaControl™ Software