User manual ELECTRO-VOICE 646 DATASHEET

[. . . ] 16 4. 0 Preparing 646 Modules for Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4. 1 Recommended Preflight Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4. 2 Module Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5. 0 646 Rigging System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] This design opts for very uniform mid- and high-frequency coverage that hovers around the 0-dB line, with a variation that is well within the optimum ±3 dB at 3, 000 Hz (important for vocal intelligibility) and nearly as uniform (±3. 5 dB) at 8, 000 Hz (the "sparkle" range). At 500 Hz, however, the uniformity is a non-optimum ±4. 5 dB. Instead of hovering around the 0-dB line, coverage has a distinct bias, rising from about 0 dB at the front to a high of +8 dB about 25% of the way back, then falling slowly back to 0 dB at the rear. This is a function of the relatively short, 4. 7-ft three-module array. The variation at 100 Hz (not shown) is even greater (± 6 dB), and drops continuously from front to back. This means that if the sound is well balanced up front, it will be "thin" at the rear (although intelligibility and clarity will be fine). Figure 8 shows the same array with a modification that provides more uniform "tracking" of the three frequencies. In general, this is achieved by attenuating the upper modules. For most of the venue, all three frequencies are within ±3 dB of each other. While levels fall at the rear of the room, the falloff is very uniform with frequency. This provides a more uniform spectral balance front to back, which may be preferred to the performance shown in Figure 4. Figure 8: A three-module 646 example of Figure 4, modified to improve the front-to-back "tracking" of all three predicted frequencies 14 Electro-Voice® 646 Series User Manual 3. 0 Designing an 646 Array (cont') 3. 42 A Five-Module Array Example Figure 9 shows another, five-module array in an 80-ft-deep venue with the front row five ft from the array and whose floor begins to rise about halfway back. The cable assembly that connects the input-panel's green PC board to the crossover/equalizer network inside the 646 module is long enough to allow the input-panel assembly to rest on a flat surface close to the 646 module. If necessary, the crossover/ equalizer cable can be temporarily disconnected. The removed input-panel assembly is shown in Figure 12. Unplug and discard the 7-pin jumper-wire connector. The attenuation module's cable connector will replace this connector. With the mounting straps on top, place the attenuation module into the pocket between the four bosses adjacent to the PC board and secure with the four screws (provided). Plug the attenuation module's cable into the 7-position header on the PC board as shown in Figure 13. Apply the supplied label to the input panel around the input connectors as shown on the 646-AM Instruction Sheet. Connect a short piece of wire (supplied) from the "SELECT" terminal to the terminal marked -3, -6 or -9 dB, as determined by 646DA. 2. 7. 18 Electro-Voice® 646 Series User Manual 4. 0 Preparing 646 Modules for Installation (cont') Figure 12: 646 input panel removed, showing green PC board and the four bosses to which the optional 646-AM attenuation module will be attached Figure 13: 646 input panel with 646-AM installed showing connector plug-in Electro-Voice® 646 Series User Manual 19 5. 0 646 Rigging System 5. 1 Overview of the 646 Flying System The external rigging parts supplied with each 646 line-array module attach to metal parts internal to each module, so that a finished array places no stress on the wooden enclosure parts. The rigging simplification inherent in the 646 modules is based on the final array being assembled in a fixed manner. [. . . ] Always follow manufacturers' recommendations for operation, inspection, and certification. Always raise and lower the load slowly and evenly, avoiding any rapid changes in speed or shifting loads that could result in a sudden jolt to the suspended system or the structure from which it is suspended. Building, Tower or Scaffold Supports: Prior to each use, the strength and load-bearing capabilities of the building, tower or scaffold structural supports should be evaluated and certified by a professional engineer as being adequate for supporting the intended rigging system (including the loudspeakers, grids, chain hoists and all associated hardware). Prior to each use, inspect the building, tower or scaffold structural supports for any cracks, deformation, broken welds, corrosion, missing or damaged components that could reduce the structural strength. [. . . ]