X-Array™ Loudspeaker Systems
easily set by coupling the grids together. The
ATM grid and couplers are shown in
Figures 8e
and
8f
. The splay angle between array columns is
determined by the position of the couplers within
the grids front and rear bars, which is illustrated
in
Figure 8g
. The front and rear couplers may be
swapped to attain small or 0° splay angles, as
shown in
Figure 8h
.
2.4 Load Distribution Front to Back
Array Load Distribution: Within the X-Array™
flying system, the ratio of the total load supported
by the rear hinges versus the front straps is im-
portant, because the front rigging straps have a
lower working-load limit then the rear rigging
hinges. The ratio of the total load supported by
the front versus the rear rigging hardware is de-
pendent on the location of the center of gravity of
the assembly of enclosures in an array column.
Two grid hinges are capable of supporting the
entire load of an array column weighing 726 kg
(1,600 lb) while maintaining a safety factor of 8:1
with no contribution from the front straps. Two
front rigging straps are capable of supporting the
entire load of an array column weighing 454 kg
(1,000 lb) while maintaining a safety factor of 8:1
with no contribution from the rear hinges. It is pos-
sible that some array shapes will transfer most or
all of the weight of a column to the front or to the
rear rigging hardware, therefore it is not valid to
assume that the total weight will be distributed
evenly over all four attachment points and to sim-
ply add up the individual working-load limits of
each piece of rigging hardware to determine how
much total weight may be suspended. Distributing
the majority of the weight of an array column to
the rear is desirable because of the higher
strength of the grid hinges and linking hinges.
If the total weight of a column of loudspeakers is
454 kg (1,000 lb) or less, the user typically need
not be concerned about the weight distribution
front to back because the front rigging straps
would be capable of supporting the entire weight
of the column while maintaining a safety factor in
excess of 8:1. If the total weight of a column of
loudspeakers is greater than 454 kg (1,000 lb) –
but less than the 726-kg (1,600-lb) maximum –
the user must be concerned about the weight dis-
tribution front to back to ensure that a safety fac-
tor of 8:1 is maintained in the front rigging straps.
Typically, the most common array configurations
used in touring and permanent-installation appli-
cations, do distribute the majority of the weight of
an array column to the rear.
Some common shapes of array columns are
shown in
Figure 14
. The center of gravity of array
columns, such as the one shown in
Figure 14a
, in
which there are no enclosures angled upward and
there are no pull ups, is located towards the rear
of the column. The weight distribution of these
types of arrays is always towards the rear of the
enclosures throughout the column, resulting in the
majority of the load being supported by the stron-
ger rigging hinges than the less-strong rigging
straps. In these cases, the user need not have
any concern for the weight distribution other than
to balance a grid.
The center of gravity for array columns, such as
the one shown in
Figure 14b
, in which the top two
enclosures are angled upward, is located more
towards the front for the top enclosure. This shifts
much of the load from the stronger rear hinges to
the less-strong rigging straps. In these cases the
user must be concerned about the weight distri-
bution front to back to ensure that too much load
is not applied to the front straps. As mention be-
fore, the user need only be concerned if the total
weight of a column of loudspeakers is greater
than 454 kg (1,000 lb). Electro-Voice recom-
mends that no more than the top two X-Array™
enclosures in a column be angled upwards, and
that the upward angle is no greater than 15° to
ensure that a safety factor of 8:1 is maintained
in the front rigging straps.
The reader should note that the rating examples
given above are valid for when the rigging hinges
and straps are loaded at nearly 0° vertically. The
reader is cautioned that the strength ratings of the
rigging hardware varies with angle, and should
consult section
3. Rigging-Strength Ratings,
Safety Factors and Special Considerations for a
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