3.0 Designing an EVA Array (cont’)
3.43 An Eight-Module Example
Figure 10 shows an eight-module array in a large theater with two balconies. Note that this array cannot be driven from one amplifier channel because only one of the modules uses the optional EVA-AM attenu- ation module. (An eight-module EVA array can be driven from an amplifier capable of driving a 2.3-ohm nominal impedance if two of the modules have attenuation modules installed. A solution is to use two amplifier channels, one for the top four modules and one for the bottom four. In order to preserve the pre- dicted array coverage, be certain that the voltage gains of both channels are the same.)
Nearly all of the 100-ft-deep main floor is covered within the optimum ±3 dB at all three predicted fre- quencies. The same uniformity applies to the first balcony (108 ft at the rear wall) although the average level drops by about 3 dB. The upper balcony (also 108 ft at its rear wall) shows a bit wider variation and less uniform tracking of the three predicted frequencies. However, the total variation in the upper balcony is still an acceptable ±4 dB.
Figure 10:
A eight-module EVA example in a large theater with two balconies
(see text above for more details)
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