LINE ARRAY
MALIK ARSHAQ
CONFIGURATIONS
Anybody who has been to a big concert or performance will
have seen line arrays in action. Apart from the loudspeakers
themselves, the way they are configured plays a huge role
in the quality, throw and overall clarity of the sound. In this
edition, we will be discussing the different configurations of
line arrays and the reasons behind it.
A line array is a loudspeaker system made up of a number of
loudspeakers. Sounds simple enough right? Wrong, this where
factors such as phase come into play. Timing differences
from different sources when combining identical signals may
sometimes result in phase cancellation, leading to loss of audio
information. Thus, the speakers of a line array system need
to be mounted in a line and fed in phase, to create a uniform
source of sound. The distance between adjacent speakers need
to be close enough to ensure that they constructively interfere
with each other to result in a louder, more evenly distributed
sound output pattern.
The need to focus the sound at the audience has resulted in
vertical line arrays becoming the norm. They provide a very
narrow vertical output pattern without wasting output energy
on ceilings or empty air above the audience. A vertical line
array displays a normally wide horizontal pattern useful for
supplying sound to the majority of a concert audience.
Two lesser-used configurations are the straight and curved
array configurations. The problem with curved arrays is
that they are not very well suited to most venues as the bottom
half will be angled down to provide extra coverage at locations
close to the front of stage, the top half will be angled upwards
at the ceiling. The problem with straight line arrays is that
the beam is far too narrow at high frequencies. A solution to
utilise the best features of both arrays is to use a curvilinear
or ‘J’ array. Comprised of a straight line portion and a curved
portion at the bottom. This provides a long throw straight line
component for people relatively far away, while the curve at
the bottom acts as an in-fill for the area directly in front of
the array.
Spiral arrays, on the other hand, are curved all the way along
the array, but the curve is progressive. This means that the top
of the array is almost straight with angles of 1° between boxes,
and increases to about 6-10° at the bottom. A well designed
spiral array could have an almost constant directivity pattern
and uniform throw that delivers sound to the audience away
from the array as w ell as ones that are directly under it.
The
Score Magazine
highonscore.com
39