User manual ELECTRO-VOICE 600D DATASHEET

[. . . ] 2 Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Basic Directivity Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Horizontal-Vertical Independence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Multiple Sources and Lobing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] A perfect solution to the problem is difficult. Where venue dimensions permit, high trim is the single most effective technique for evening out bass SPL from front to back. In the preceding illustrations, trim height was 32 feet (~10m) to top of stack. Figure 20 shows the same beamformed array as in Figure 19, but with a trim height of 65 feet (~20m) to top of stack. The level shift from front to back is much less. 14 600D · A PRACTICAL GUIDE REV. 1 / JUNE 7, 2010 Blue Red Green 40Hz 60Hz 90Hz Figure 20. Beamformed; trim height 65ft (~20m). Flown Center Subbass Line Arrays. Where staging and rigging considerations permit, a flown center stack of subwoofers can give excellent results. There is zero lobing, the horizontal coverage is essentially 360°, and the vertical coverage can be controlled well by beamforming. Figure 21 shows the coverage of a flown center cluster of 12 EV Xsub woofers in an arena venue. In all cases, the delay value must always be adjusted to match the spacing between loudspeaker cones. If each Xsub shown in Figure 23 were a column of Xsubs instead of a single Xsub, we would have a gradient line array. Gradient line arrays have useful properties and will be discussed further below. 17 600D · A PRACTICAL GUIDE REV. Characteristics of Gradient Arrays Pattern Options. For a given gradient pair, the pattern can be varied by changing the rear-element delay. Available patterns are similar to those of microphones: cardioid, hypercardioid (various types), and figure-8. Figure 24 and Figure 25 show four pattern options for the back-to-back Xsub pair from the example above. Figure 24. Right: Hypercardioid, ±135° nulls. Audience on the right. 18 600D · A PRACTICAL GUIDE REV. Left: Hypercardioid, ±120° nulls. When constructing a gradient pair, it is important to understand the role of element spacing. [. . . ] This equalization will not interfere with the subwoofer crossover as long as it is applied equally to both the subwoofers and the main array. This principle leads to one of two signal path diagrams, depending on whether the subwoofers are driven as part of the main mix or from their own mix. Figure 36 shows the case in which the subwoofers are driven from the main mix. The subbass contour EQ is configured as a normal pre-crossover equalizer. [. . . ]