User manual ELECTRO-VOICE EVI-28 EDS

[. . . ] The EVI-28 full-range Vari Intense® loudspeaker system is the ideal system whenever high output full frequency range material must be reproduced for balconies, cinemas, distributed systems and smaller rooms in churches, gymnasiums, auditoriums, hotels and civic centers. Frequency Response The combination of dual 210 mm (8-inch) woofers, a wide-bandwidth high-frequency driver and an equalized, delay-, frequencyand amplitude-shading crossover results in the wide and smooth overall response shown in Figure 1. The EVI-28's long-throw axial frequency response was measured in Electro-Voice's large anechoic chamber at a distance of 10 feet with a swept sinewave input of 4 volts. Directivity The polar response of the EVI-28 speaker system at selected one-third-octave bandwidths is shown in Figure 2. [. . . ] If the under-balcony seating area is only 35 feet deep, then the enclosure should be tilted down by about 10 degrees relative to the floor in order to prevent excess slap echo and preserve intelligibility. Figure 10 shows a typical small-room application, perfect for a 20-foot by 30-foot boardroom or meeting hall. In this case, the head height is actually defined by a standing height of approximately 6 feet, so the long-throw axis should be very close to vertical. Then the included 40 degree angle points directly towards the entire listening area, minimizing slap echo while retaining a full width, high intelligibility and even SPL throughout the listening area. manufacturer to develop and publish a power test closely related to real-life conditions. First, we use a random-noise input signal because it contains many frequencies simultaneously, just like real voice or instrument program. Second, our signal contains more energy at extremely high and low frequencies than typical actual program, adding an extra measure of reliability. Third, the test signal includes 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 the average, just like actual program. The long- 2 EVI-28 250-Watt T wo-Way Compact Vari Intense® Speaker System term average level stresses the speaker thermally (heat). The instantaneous peaks test mechanical reliability (cone and diaphragm excursion). The sine-wave test signals sometimes used have a much less demanding peak value relative to their average level, providing a much higher power handling specification than is appropriate for real-world use. In actual use, long-term average levels exist from several seconds on up, but we apply the long-term average for eight hours, adding another measure of reliability. Additional extremely highstress tests developed in-house push components to the limits to ensure long-term reliability under the most extreme cases of abuse. Specifically, the EVI-28 is designed to withstand the power test described in ANSI/ EIA RS-426-A 1980. To obtain the spectrum, the output of a white-noise generator (white noise is a particular type of random noise with equal energy per bandwidth in Hz) is fed to a shaping filter with 6-dB-per-octave slopes below 40 Hz and above 318 Hz. When measured with the usual constant-percentage bandwidth analyzer (one-third-octave), this shaping filter produces a spectrum whose 3-dBdown points are at 100 Hz and 1, 200 Hz with a 3-dB-per-octave slope above 1, 200 Hz. This shaped signal is sent to the power amplifier with the continuous power set at 250 watts into the 6. 9-ohm EIA equivalent impedance. Amplifier clipping sets instantaneous peaks at 6 dB above the continuous power, or 1000 watts peak. The EVI-28 has been thoroughly tested at an AES equivalent power level of 350 watts continuous for 2 hours with 1, 400 watt peaks. This procedure provides a rigorous test of both thermal and mechanical failure modes. Amplifier Power Recommendations As noted in the Power-Handling Capacity section above, the EVI-28 has a randomnoise power capacity of 250-watts long term (1000-watts peak) per ANSI/EIA RS-426-A 1980. The following guidelines will help relate this number to an appropriate power amplifier output rating. [. . . ] Architect's and Engineer's Specifications The loudspeaker system shall be of the full-range type consisting of dual 210-mm (8-inch) high-efficiency, extended-voicecoil, high-power woofers in a vented enclosure and a 25. 4 mm (1-inch) exit compression driver loaded with a small-format Vari Intense® horn. The loudspeaker system shall employ a passive crossover that provides amplitude, frequency and delay shading to the 8-inch woofers and provide high-frequency protection for the compression driver. Power handling shall be 250 watts of pink noise with an 6-dB crest factor for eight hours, or 350 watts of pink noise with an 6-dB crest factor for two hours, bandlimited from 62 Hz to 25 kHz. Frequency response shall be smooth and uniformly usable from 62 Hz to 25 kHz. [. . . ]