8
How to Operate the MQ109B
How to Operate the MQ109B
The most effective means for accurately setting the
MQ109B controls is by use of a One Third Octave Pink
Noise Generator and calibrated sound level pressure meter.
A one third octave real time analyzer can also be used. The
pink noise generator output is connected to the preamplifier
or control center, (set for flat response), and on to the power
amplifier and speakers. The sound level microphone should
be located in the primary listening area.
1. Measure the backround noise level in the room.
2. Adjust the output level of the pink noise generator until
the output is at least 20dB above the backround noise
level in the room, as measured in step one.
NOTE: The Pink Noise Generator should be set to broad
band noise.
3. Adjust the output of
the pink noise gen-
erator for one third
octave noise.
4. Sweep the frequency
range of the pink
noise generator
from 20Hz to
10,000Hz.
The room sound level
measurements will indi-
cate the frequency re-
sponse of the system
and reveal the specific
frequency ranges where corrective equalization is needed.
The variation from the ideal may be either a peak or a dip
in the response at more than one frequency. The variations
can also be of different amplitudes, and may be broad or
narrow in bandwidth..
NOTE: Do not try to adjust for a perfectly flat response from
20Hz to 20,000Hz as this will result in a totally
unnatural sound quality. Rather adjust for a smooth
response.
Select the MQ109B BOOST/CUT control that is closest
to the frequency of each of the undesired peaks or dips in
response and adjust them as needed to correct the amplitude
deviations. Refer to figure 1.
5. Adjust the appropriate Q controls to compensate for the
bandwidth of the peak or dip.
6. Adjust the LOW FREQ COMP control to achieve the
best possible low frequency response.
NOTE: Figures 2 through 8 show the frequency range,
bandwidth and amplitude characteristics of each of the
MQ109B controls.
It will be necessary to repeat steps 4 through 6 as often as
necessary to confirm that the equalization adjustments have
corrected the response deviations.
Figure 1
