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6. USE OF THE PHASE CONTROL
M&K Sound X Series subwoofers feature a continuously variable phase control from 0 to180
degrees. This control will help you to fine-tune the transition between sound sent to your main
speakers and your subwoofer.
In order to optimize the integration of your subwoofer with your main speakers, you should
perform a phase test. This test will help you to achieve a seamless transition between your main
speakers and subwoofer(s).
A phase test is helpful, because when satellite (or main) speakers are located in a different
location from the subwoofer, each speaker is located at a different distance to the listener. Even
small differences in distance mean that the arrival times of sound from the various speakers to
the listener are also different. These time differences can cause phase anomalies, which are
destructive to the reproduction of sound in your room. Be sure to re-do this test if you move your
speakers.
To begin, select something to play through your speakers that you are familiar with. A stereo CD
is a good choice since surround sound material with its complexity can make this test more
difficult. While playing the CD through your left and right front speakers along with your
subwoofer, listen to the mid-bass region (70 - 100 Hz) – that part of the audio spectrum where
instruments like bass and drums need both the satellites and subwoofer for accurate
reproduction.
Adjust the phase control from 0 degrees to 180 degrees. Note the difference between the two
settings. If you hear a tighter, more defined quality to the sound with better low bass reproduction
with one of these options, then that is probably the best setting. If you are using two or more
subwoofers, perform this test with each subwoofer individually with the others turned off.
If your preamp/receiver features a phase control, you can further fine-tune your system by
adjusting this control between 0 and 180 degrees. When you hear the best balance between
stereo image localization, maximum low bass impact and well defined output in the mid-bass, you
have found the correct setting.
If you hear little or no difference when adjusting the phase control knob or phase switch, set it to
the 0 degree (default) position.
A more accurate method of establishing the phase relationship between your satellites and
subwoofer or subwoofers is to use a pink noise generator and a spectrum analyzer. Place the
microphone at the listening position and run pink noise through the system. Take note of the mid-
bass region (70 - 100 Hz) on the analyzer’s display. The setting that shows the most output in
that region and also shows the best low bass response has the correct phase.
