The Ins And Outs Of Polarity - Mackie MR10Smk3 Owner's Manual

The Ins and Outs of Polarity

The MR10Smk3 studio subwoofer includes a switch
that allows you to quickly invert the polarity of the
subwoofer's output relative to the input signal it is
receiving from the mixer or other sound source.
But what exactly does that mean? A subwoofer works
by literally pumping air as the woofer cone moves in
and out with respect to the cabinet in which it is
housed. It does so according to the low-frequency
portion of the signal it receives from the sound source.
The woofer cone is simply following the waveform as
seen in the sine wave in Figure 1. As the sine wave rises,
the woofer cone pushes out. Likewise, as the sine wave
falls, the woofer cone pulls into the cabinet. A musical
signal is much more complex, of course, but the same
principle applies. Movement of the woofer cone causes
air pressure changes that we perceive as sound.
When the polarity switch [7] is to the right,
the original waveform is simply reversed 180˚
[see Figure 2]. Again, the subwoofer cone follows
the waveform. However, this time the woofer cone starts
by pulling into the cabinet followed by the woofer cone
pushing out. If you have ever experimented with a
subwoofer polarity switch, you may not have noticed
any changes to the sound regardless of its position,
especially if you are listening to just the subwoofer.
This is normal, as our ears perceive them both at the
same time.
The polarity switch comes into play when the
MR10Smk3 studio subwoofer is paired with a studio
monitor. Ideally, the woofer cones of the subwoofer and
monitor would work together by pushing and pulling in
unison. MR10Smk3 studio subwoofers are designed to
be used in a broad range of applications. The flexibility
provided by the polarity switch is necessary to ensure
that you are receiving the best possible sound from your
system, regardless of your setup.
Polarity Waveforms
Figure 1: 0˚
<–– Time ––>
Figure 2: 180˚
<–– Time ––>
Owner's Manual
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