LD Systems DDQ Série Manuel D'utilisation page 6

DDQSUB CARDIOID TECHNOLOGY:
The DDQSub cardioid technology makes it possible to influence the dispersion behaviour of a subwoofer setup
through the use of specific DSP programming. This makes it possible to transform a nearly omnidirectional
dispersion characteristic into a cardioid dispersion characteristic in the sub-bass frequency range This requires
at least two subwoofers of the same type. By setting up one of the subwoofers within a cardioid setup so that
it is rotated by 180° or spatially set off, the sound energy dispersed behind the bass array can be minimised by
means of time delay and amplitude correction. This is achieved by setting up the subwoofer in one of four setups
and activating one of the preset DSP programs for each subwoofer
SCHEMATIC DIAGRAM OF A CARDIOID SUBWOOFER ARRAY WITH FUNCTIONALITY AND EFFECT
d = λ/4
Rear Front
= 2* λ/4
t
The spatially separate positioning of the subwoofers results in a time delay between the front and rear subwoofers.
This difference is adjusted within the DSP preset through time delay, amplitude, and phase correction so that maximum
addition of sound waves results in front of the subwoofer array. With the same setting, sound waves cancel out one
another at the rear of the subwoofer array, thus producing the desired rear attenuation of the overall system.
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