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TD-001536-01-A
About the KS212C Cardioid Subwoofer
The term Cardioid refers to the heart-shaped coverage pattern of an audio device. A cardioid microphone is designed to
be most sensitive at the front (on-axis), and least sensitive at the rear (180 degrees off-axis). A Cardioid Subwoofer
operates exactly the same way, and is loudest at the front and quietest at the rear.
Low frequency energy, from subwoofers, is effectively omnidirectional in nature (equally loud in all directions). This is
because low frequency wavelengths are much longer than the dimensions of the subwoofer enclosure, and therefore
“wrap” around it. A cardioid subwoofer arrangement employs both front- and rear-firing woofers, and through some
clever use of spacing, delay, and polarity, a cancellation of rear-firing energy is created behind the subwoofer, while also
enhancing the forward-firing energy.
The KS212C is powered by a Dual 1800 W Class D amplifier, processed with QSC’s latest DSP technology, and
incorporates dual, 12-inch, long-excursion drivers that are each arranged in a sixth-order bandpass chamber. Through
complex processing, these mirrored components interact at the rear of the enclosure to produce a desirable cancellation,
while simultaneously interacting at the front of the enclosure to produce equally desirable summation. This results in a
net 15 dB higher output at the front of the cabinet than at the rear. To put this into perspective, 15 dB is the difference
between 30 watts and 1000 watts.
— Figure 2 —
Subwoofer Energy Dispersion
Rear
Front
-15
dB
Rear
Front
Cardioid
Typical
