Mackie SRM1801 Benutzerhandbuch

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Mackie’s SRM1801 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 Invert switch [6] is engaged, the 

original waveform is simply reversed 180º (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 as the same.  

The polarity invert switch comes into play when the 

SRM1801 subwoofer is paired with a loudspeaker.    
Ideally, the woofer cones of the subwoofer and  
full-range loudspeaker would work together by  
pushing and pulling in unison. SRM1801 subwoofers are 
designed to be used in a broad range of applications, 
and with a wide variety of full-range loudspeakers. 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.

Listed below are some recommended configurations 

for pairing a Mackie SRM1801 subwoofer (using the 
High-Pass output) with a Mackie full-range  

 

loudspeaker. These settings are a good start, but be sure 
to experiment to find the best sound for your venue. The 
loudspeakers may be stacked, pole-mounted, or flown. 
 
•

SRM450v2 full-range loudspeakers - Disengage the  

     Polarity Invert switch on the SRM1801.  
 
•

TH-15A full-range loudspeakers - Engage the          

      Polarity Invert switch on the SRM1801.

In alternate setups where the full-range loudspeakers 

are not co-located with the subwoofers or are not    
connected to the SRM1801 subwoofer’s High-Pass 
outputs, you will need to experiment with the Polarity 
Invert switch to determine which setting gives you the 
desired bass response for your application.