Mackie MR10Smk3 Owners Manual - Page 9

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˚ Figure 2: 180˚ Amplitude Amplitude Owner's Manual 9