8 SUBWOOFER MEASUREMENT AND
CALIBRATION
The approach taken to measure and calibrate subwoofers is different than for speakers.
Instead of using windowing, a nearfield measurement is taken so that the direct sound
from the subwoofer dominates the room effects.
(See page 121 for an alternative but more advanced approach to low-frequency
measurement that can be used with subwoofers.)
If you are not using subwoofers, skip this chapter.
8.1 MEASURE THE SUBWOOFER
The diagram below illustrates how a subwoofer is measured. The subwoofer should be
measured in its intended location. Position the microphone 5 to 20 cm (2 to 8 inches)
from the subwoofer cone.
Set the controls on the subwoofer for minimum processing: disable its low pass filter
(crossover) if possible, or if not, set it to its highest frequency; turn off any equalization
in the sub; and set any phase or invert controls to their neutral positions.
Figure 2. Subwoofer measurement setup
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