User manual ELECTRO-VOICE MH4020AC EDS

[. . . ] The MH4020AC's potentially high acoustic output, stable directional characteristics, and extended low-frequency performance make it highly suitable for music and speech reinforcement in large indoor and outdoor venues. At the heart of the MH4020AC are four DL10X-SH 10-inch water-resistant drivers (U. S. The driver has been specially developed for the MH series of horns. It incorporates a unique diaphragm construction of Kevlar® and epoxy. 1 This combination of high-technology materials produces a diaphragm with a strength-toweight ratio on the order of twice that of conventional materials. [. . . ] Connections The four DL10X-SH drivers in the MH4020AC horn have a nominal impedance of 16 ohms each and can be accessed individually and driven independently. However, it is more typical to combine the drivers. Figure 9 illustrates some different combinations. It is particularly important to bear in mind the impedance of any cabling and specifications of the amplifier before selecting a specific combination. Whatever the combination selected, the polarity of the drivers must be considered (see Figure 9 and Polarity of the DL10X-SH Drivers section). Directivity The axial directivity factor R of the MH4020AC was computed at each of the one-third-octave center frequencies over the frequency range noted from the horizontal/ vertical polars shown in Figure 7. Directivity index (Di) was taken over the same frequency range. Beamwidth Plots of the MH4020AC's 6-dB-down total included beamwidth angles are shown in Figure 6 for each of the one-third-octave center frequencies noted. Polar Response The directional characteristics of the MH4020AC were obtained by selecting the horizontal and vertical details from a full set of polar data measured in EV's large anechoic chamber. The measurement microphone was placed 6. 1 m (20 ft) from the center of rotation of the horn which, in turn, was 0. 94 m (3. 08 ft) behind the mouth of the horn. Polarity of the DL10X-SH Drivers For Manifold Technology® to operate correctly, the drivers must be operated "in phase. " In other words, for parallel connection, the DL10X-SH's must be connected so the negative terminals of the drivers are connected together, and the positive terminals are connected together. Service In the unlikely event the MH4020AC requires service, each DL10X-SH easily can be replaced or serviced by removing the back cover and then removing the driver. A service data sheet is available from ElectroVoice. Power Handling Capacity To our knowledge, Electro-Voice was the first U. S. manufacturer to develop and publish a power test closely related to real-life conditions. A random-noise input signal is used because it contains many frequencies simultaneously, just like real voice or instrument program. The signal contains more energy at extremely high and low frequencies than typical actual program, adding an extra margin of reliability. The test combines not only the overall "long-term average" or "continuous" level--which our ears interpret as loudness--but also short-duration peaks which are many times higher than average, just like actual program. The long-term average level stresses the speaker thermally (heat). The instantaneous peaks test mechanical reliability (cone excursion). Note that the sine-wave test signals sometimes used have a much less demanding peak value relative to their average level. In actual use, longterm average levels exist from several seconds on up. [. . . ] If such malfunction occurs during the specified period, the product will be repaired or replaced (at our option) without charge. The product will be returned to the customer prepaid. 56 mm (2. 2 in. ) 1, 878 mm (73. 9 in. ) 6. 3 mm (. 25 in. ) DIAMETER HOLE, 24 PLACES. 19 mm (. 75 in. ) DIAMETER HOLE (ALL BRACKETS HEAVY-DUTY #10 GAUGE POWDER-COATED STEEL), 18 PLACES. 790 mm (31 in. ) REF. 371 mm (14. 6 in. ) 274 mm (10. 8 in. ) Figure 9--Wiring Diagram (+) 8 OHMS + + (+) 16 OHMS + + (+) 16 OHMS (+) 8 OHMS + + (+) 16 OHMS + + (+) 16 OHMS 7 MH4020AC Coaxial Stadium Horn System Specifications* Useable frequency Range: Coaxial Version (See figure 2) 100-20, 000 Hz Non Coaxial Version (figure 3) 100-4, 000 Hz Power Handling, long-term average broadband per EIA RS-426A, (see page 2 for complete test description): 1200 watts Sensitivity (Sound Pressure Level @ 1 Meter, 2. 83 Volts input, band limited pink noise in anechoic environment): 109 dB Average Efficiency: 25% Nominal Coverage Angle (See figure 6), Vertical: 40° Horizontal: 20° Mid-bass Transducers, Configuration: 4-way manifoldy manifold Transducer Complement: DL10X-SH (4), with water-resistant cones and Ring-Mode Decoupling (RMDTM) Nominal Impedance in pass band (See figure 4): 8 Ohms/ parallel pair D. C. [. . . ]