Master Audio
Xcellence Line Array Series 208.Ver 1.2 Sep 12
46
11. TIME ALIGNMENT IN PA SYSTEMS
In common PA systems the frequency range is divided into different ranges which are
reproduced using different cabinets (subwoofers for the bass range and top cabinets
for the mid-high range). This means different locations and positions of the sound
sources.
This leads to some interferences in the crossover range, causing notches and peaks
in that area. Time alignment (delay) tries to adjust the arrival time of sound so that in
the crossover area it arrives at the same time.
Fig.36.This system is not completely aligned because d1 and d2 are not equal.
If we do not put a delay on the subwoofer cabinets we may notice a dramatic
cancellation in the frequency range being shared by both cabinets or in the crossover
frequency between the subwoofer units and the top units.
Fig.37. Magnitude and phase response of the complete unaligned system (with no
delay)
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