Systems with Left-Right Arrays
For systems with left-right arrays, it’s good to understand the pattern of each individual array, but optimum design requires considering both arrays at once.
If we had perfect control of directivity, we would make the left array cover only audience left, and the right array cover only audience right.
Since this is not possible, the patterns overlap, and lobing results. The system design challenge is to minimize the lobing while at the same time covering the whole audience.
When the arrays are wider than about 10 feet (3m), you can take advantage of their narrow patterns to reduce lobing.
By aiming the left and right beams offstage, you can reduce pattern overlap in the center while widening overall coverage at the same time. Figure 13 illustrates this.
In the right-hand diagram, the woofer arrays have been aimed offstage at a 30° angle. In the right-hand picture, the nulls are shallower and coverage at 90Hz is improved.
Beamforming can have approximately the same effect as offstage aiming. Figure 14 illustrates the effect of applying beamforming delays to the array of Figure 13. The results are quite good.