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en | Flying the system
3a. Single Grid Pick
Figure 9.10: Comparing array structural strengths
The arrays in Figures 3a and 3b are the weakest. The highest force in both of these arrays will
be on the rear rigging points of the top element. The long length of the X12TE-GRID extended
behind the loudspeaker acts as a large lever arm (like a wrench) that significantly increases
the force on the top enclosure rear rigging. Another way to visualize this is to think of the grid
being held in a fixed position. Because the center of gravity of the entire loudspeaker column
is so far towards the back, the column will tend to rotate counterclockwise to tilt up. The rear
rigging of the top enclosure will be in tension resisting the rotation.
Whenever a large portion of grid is extended behind the top loudspeaker as shown in Figures
3a and 3b, fewer elements will be allowed to be suspended before the working-load limit of
the top element rear rigging is exceeded. This condition most commonly occurs with the
X12TE-GRID when the loudspeakers are in the A position. The same condition can occur when
a large portion of grid is extended in front of the top loudspeaker. This could occur with a
steep up-tilt angle with the X12TE-GRID with the loudspeakers in the C position on the grid.
The X12TC-GRID is not subject to this condition, because the grid is just slightly longer than
the loudspeaker enclosures.
The array in Figure 3d is the strongest because the load is shared between the top and bottom
of the array. This configuration will allow the highest number of elements to be suspended
and is most commonly employed when a greater down-tilt angle is required.
Unless extreme down-tilt angles are employed, the highest forces in the array in Figure 3d will
be on the rigging of the top element. The X12PU-BGK bottom grid does not have as high of a
strength rating as the top grids X12TC-GRID or X12TE-GRID.
The array configuration shown in Figure 3c has greater capability than those shown in Figure
3a and 3b, but less capability than the array shown in Figure 3d. In this case, the load of the
loudspeaker column is shared between the rigging attachment points of the top element and
the pull-up assembly. However, the pull-up to the grid introduces forces that otherwise would
not exist due to gravity alone. For the array configuration in Figure 3c, the highest forces
typically occur at either the top element or at one of the elements near the bottom of the
array.
2019-07 | 04 | F.01U.310.953
3b. Double Grid Pick
3c. Single Grid Pick
Pullup to Grid
Installation manual
X-LINE ADVANCE System Rigging & Transport
3d. Double Grid Pick
Pullback to Venue
Electro-Voice
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