JBL HLA 4895 Owner's Manual page 31

Section 7. - HLA SYSTEM ARRAY SETUPS
The nominal horizontal coverage one HLA 4895 speaker unit is 40 degrees from 315 to 16,000 Hz. The
nominal vertical coverage of one HLA 4895 speaker is 30 degrees from 315 to 16,000 Hz. The side angles of the
HLA 4895 Spaceframe are constructed at 15 degrees to match the horizontal coverage pattern of its Waveguide to
that of adjacent speakers in the same row for typical medium-sized venue applications.. This allows the
construction of arrays that offer smooth, even horizontal coverage.
HLA speakers can be configured several ways to achieve the required SPL and coverage. The horizontal
angle between adjacent speakers in an array can be varied from 0 degrees, where neighboring speakers are facing
into the same plane, to 30 degrees, where the horizontal angle of the speakers matches the angle on the sides of
the Spaceframe. Optimum horizontal coverage will be obtained with a slight overlap between adjacent cabinets,
as shown below.
HLA Array Configurations and Adjustments
Adjustment of adjacent HLA units can be made in increments of 5 degrees when using the MEGS-
JBLHLA Truss system to suspend the array. There are seven choices of horizontal splay angle afforded by the
MEGS-JBLHLA Truss modules: 0, 5, 10, 15, 20, 25, and 30 degrees.
At one extreme (0°) the speakers are facing into the same plane, increasing the amount of power
delivered into the listening area at the expense of potential interference or "comb filtering" between the two
speakers.
On the other hand, if the two adjacent speakers are subwoofers, there will be increased coupling
between them (resulting in increased apparent sound pressure levels) when they are facing into the same plane.
This can be beneficial, and may be desirable in situations that demand the highest possible sound pressure levels
within a defined area of coverage, such as music nightclubs and discotheques.
At the other extreme the horizontal coverage of the speakers matches their side-angles, providing the
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