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Phase Control
The Phase Control switches allow the VRM subwoofer to be acoustically aligned with other speakers in
your system. 0˚, -90˚, -180˚, or -270˚ degrees of phase shift at 80Hz can be selected using DIP switch-
es 2, 3, and 4. For 0˚ degrees of phase shift, leave all three switches in the OFF (up) position. –270˚
degrees of phase shift occurs when switch 2 is selected in the ON (down) position. –180˚ degrees can
be achieved by selecting both switches 2 and 3 in the ON (down) position. Finally, selecting all
switches 2, 3, and 4 in the ON (down) position produces –90˚ degrees of phase shift.
Set-up Procedure
1) Place all your speakers and any acoustically significant components in their working location in the
listening environment.
2) Insert a sine wave signal into the audio path. Be careful to turn down the level before turning on
the amplifiers.
3) Choose a frequency that corresponds to the crossover frequency between the VRM subwoofer and
the reference monitors.
4) From the listening position, alternate between the VRM subwoofer and the full range speakers and
adjust the levels until they have the same acoustic output. Use an SPL meter, a microphone on a VU
meter, or your ears to accomplish this.
5) With all speakers on, try the 0˚, -270˚, -180˚, and –90˚ degree phase settings. The setting with the
highest SPL reading from your listening position will produce the most effective acoustic alignment.
6) Set the VRM10s/VRM12s/VRM15s gain control according to your preference. This will not affect the
acoustic alignment of your system.
Here is a list of some items that can affect acoustic alignment: Relocating speakers, changing the VRM
subwoofer Low Pass frequency, changing the acoustic environment (i.e., traps, diffusers, etc.), changing
the listening position.
Although this procedure produces the maximum achievable acoustic gain for your system, listening
tests may still lead you to prefer another setup.
Example of how phase misalignment between high frequency speakers and a subwoofer can cause
cancellation
Operation
