Mackie CRDV, Руководство пользователя

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CR8S
-XB
T and CRD
V
CR8S-XBT and CRDV
The CR8S-XBT 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 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 CR8S-XBT subwoofer is paired with studio
monitors. Ideally, the woofer cones of the subwoofer
and monitors would work together by pushing
and pulling in unison. CR8S-XBT 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.
The Ins and Outs of Polarity
<–– Time ––>
Figure 1: 0˚
Amplitude Amplitude
Figure 2: 180˚
<–– Time ––>
Polarity Waveforms