EVI-12, EVI-15 and EVI-28
Loudspeaker Systems
Applications Guide
Welcome to the world of Vari Intense® horn technology from Electro-Voice. This Applications Guide is not intended as a “very intense” description of installation procedures, but more as a partial description of applications and a discussion with the designer to help you understand this revolutionary technology and use the Electro-Voice Vari Intense® systems to install better-sounding systems and significantly reduce time and material costs.
In a nutshell, here are the major advantages of the new EVI systems:
• Rectangular coverage pattern.
Traditional horns deliver an elliptical pattern to the floor. VI horns deliver a rectangular pattern, which helps to fill in the corners of the room. No more costly delay lines or cheap seats!!
• Even SPL front-to-back.
The unique, patented throat and flare structure of the VI horn delivers a 6-10 dB hotter signal to the rear of the room, eliminating earstrain at the back of the seating area and painful ears at the front.
• Greater Intelligibility.
VI horns deliver sound to fill only the floorplan, providing uniform direct-field SPL and an order of magnitude less energy into the reverberant field. This provides an increase in midto high-frequency intelligibility of 6 dB in most applications.
• One horn replaces two.
With VI technology we’ve eliminated the destructive interference which occurs between longand short-throw horns. We’ve also eliminated the cost of a properly designed two-horn system which must include another power amplifier channel for good power control and impedance matching.
• Labor savings in the box.
With structural rigging from the factory, these systems will fly more conveniently and in less time than many competitive products. In addition, less time is spent on the aiming and repositioning that is required with traditional long- throw/short-throw horn combinations. This will save you additional money.
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Installation procedures for any conventional loudspeaker are fairly well-defined and easy to understand: find an appropriate hanging height and position that affords a clear path to the listening area (such as above the center of a stage or above the lectern in a church), and aim the loudspeaker towards the center or just to the rear of center of the room. With this method you hope to cover the majority of the room with fairly consistent sound, but the mid and high frequencies never seem to fill perfectly. It is frequently aimed a little too far back and there is a large amount of slap echo, or the front row is too loud, the back row too soft and the front and back row corners sound muted due to a lack of high-frequency energy. Other solutions to filling the room have been suggested and implemented, including a dual-horn format (one long throw and one short throw). This method works fairly well, but encounters several problems: the added expense of another horn/driver combination; the vastly increased time to physically install and then tune the level and aiming of two horns; the inevitable destructive interference patterns throughout the listening area; the expense of another amplifier channel to achieve correct impedance matching; and the need for a very aesthetically clean installation, with no odd-looking (to the customer) dangling horns. Another solution is to have a horn that is variable angle, in order to throw a narrow pattern to the back of the room. The problem with this concept is that this doesn’t take into account the drop in SPL between the near throw (about 25 feet) and the far throw (about 70 feet), so the high frequencies are about 10 dB down in the back of the room. To solve all of these problems, the Vari Intense® horns were invented, yet another innovation in the long tradition of Electro-Voice. When properly aimed, the Vari Intense® horns can provide extremely even SPL throughout an entire room, filling in the corners without pushing too much energy at the back wall, thus avoiding slap echo. The rules of fixed installation have just changed...
The Electro-Voice EVI-12, EVI-15 and EVI-28 enclosures are the first in a new generation of problem-solving systems. The new systems are designed as a package, with easy mounting, refinishing ability, lightweight, compact and unobtrusive size and shape and the classic musical sound that Electro-Voice is known for. The new small-format VI horn maintains consistent directional control down to 2,000 Hz. In the EVI-12 and EVI-15 the VI horn is optimally crossed over to an specially
angled woofer. Note: the 12-in. driver in the EVI12 is at a different angle than the 15-in. driver in the EVI-15, optimizing the floor pattern with the differing directivities of the two drivers. In the EVI-28, the VI horn is crossed over to a pair of verticallyarrayed 8-inch woofers with a proprietary technique that provides delay, amplitude and frequency shading to the two woofers.
The EVI-12, EVI-15 and EVI-28 systems are installed just like any conventional loudspeaker, keeping in mind a few simple guidelines. Let me preface these guidelines with a simple but important comment: the VI systems are extremely versatile and will work in a large variety of applications. They will work well with tall ceilings, short ceilings, rectangular rooms, slightly trapezoidal rooms and a whole host of odd shapes so long as the coverage area is fairly close to rectangular. The larger EVI-12 and EVI-15 have been tested in rooms with 12-foot ceilings and performed very well, although with reduced width of throw. A single EVI-12 was installed in a room 75-foot by 150-foot and an average RT60 of 4.5 in the mid band and performed very well with good intelligibility and a minimum of slap echo. It has been thought in the past that if the floor pattern does not fit the VI horn exactly, then it cannot be used at all. This is not the case, and if it were the case, we could not use standard constantdirectivity horns in most applications either. The larger VI systems have an “optimum” room that is approximately twice the height in width and three times the height in length. This is the ideal condition, but the figures and descriptions that follow should give you a good feel for the wide-range capabilities of the systems.
EVI-12 and EVI-15 Installation:
The nominal floorplan that the system will cover with equal SPL is approximately two “units” wide by three “units” long, where the height of the loudspeaker defines the size of the “unit.” For example, if the loudspeaker is 18 feet above the floor, it will typically cover a floorplan of about 36 feet wide by 54 feet long. In this typical installation (see Figure 1), the back panel of the loudspeaker is mounted approximately 0.6 units (about 11 feet) back from the first row and has a nominal angle of the top of the enclosure parallel to the floor or slightly tilted back (2 to 3 degrees). For rooms that are much longer than normal, the VI systems are very easy to aim and position to fill the entire length. Experiments in actual listening rooms have shown that with
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the same mounting height of 18 feet, but with the front of the enclosure tilted up by approximately 10° (see Figure 2), the total floorplan now encompassed the same 36 foot width, but at least 64 feet in length, an additional 10+ feet of extension. Of course, the front row position has moved back about 5 feet with the change in angle as shown, but this is easy to account for when initially positioning the system (and is exactly what happens if you take a conventional system and change the angle). For rooms that are closer to square, tilting the loudspeaker system down by 15° provides a very clean square pattern. In this case, the offset to the first row is about 0.25 times the height of the system. For example, a tall, square room is about 60 feet wide, and only 65 feet long. Tilting the enclosure down by 15° at a 30 foot mounting height makes a 60 foot wide by 60 foot long pattern. The offset to the first row is 0.25 multiplied by the 30 foot height, or about 7.5 feet forward from the back of the enclosure. Minor adjustments in aiming will make the SPL fill the room very evenly with no loss in tonality in the corners and high overall intelligibility.
By contrast, a typical two-way system with a 60° x 40° CD horn in the same mounting location as Figures 1 and 2 (see Figure 3) produced a floor plan that sounded tonally fairly consistent with a 20to 24-foot width and 30-foot depth with an offset of nine feet to the front row. On paper, this seems like adequate performance, but in the room it has very noticeable (6 dB or greater) variation in overall level from side to center, and in some aiming cases over 10 dB of variation from front to back as well as a pronounced lemon shape. The sides of the first three to five rows in a church and the last few rows were noticeably muted and much lower in overall level. As mentioned before, a two-horn system can work fairly well, but the physical offsets required for installation inevitably result in some amount of destructive interference throughout the room (see Figure 4). Figure 4 was produced using a 90° x 40° CD horn aimed down by 65° and a 60° x 40° horn aimed down by 30°. The actual physical offsets were used to simulate the floor response in direct-field SPL. The displayed figure agrees very well with the measured response, showing a 14-dB variation at 4kHz in a distance of 3 feet horizontally. Tonal changes as a result of interference pattern change versus frequency were clearly audible in an acoustically well-behaved room, but were overall much less audible than for a single system with a conventional CD horn. Locating drivers
and horns closer together than possible with me- dium-format horns will produce somewhat better results, but will always result in fairly severe lobing. Polar measurements in 2° increments show the lobing very well, but the smoothingrequiredfortranslationtotheEASE10° resolution database will eliminate the vast majority of peaks and dips, resulting in what appears to be a fairly smooth simulation. In contrast, the new VI systems have no problems with interference, and maintain very good tonality even far to the sides and to the back, outside the “equalSPL” pattern area. This effect is due to the precise matching of directivities in the midrange and treble, giving a consistent (although noticeably quieter) frequency response out to nearly 50 feet in width and 65–70 feet in length from the same 18-foot height and 0° aiming angle. This has the advantage of providing a much more uniform power response into the reverberant field, ensuring that the inevitable reflections (minimized by the VI concept) are consistentintonalquality.
EVI-28 Installation:
The EVI-28 makes use of the same high-fre- quency horn as the EVI-12 and EVI-15, but includes a pair of high-power, high-efficiency 8” woofers in a very compact package. The system is provided with a 2,000-Hz passive crossover featuring tweeter protection and a proprietary passive equalization circuit that provides frequency-shading, am- plitude-shading and time delay to the two woofers. An Acoustic Lens Filter on the grille helps to eliminate spurious lobes and provides a degree of acoustic loading. These features heavily modify the polar response of the two woofers, providing an extremely uniform polar pattern with a shape that matches the VI horn’s unique SPL profile. They also smooth the transition between woofers and the horn to minimize horizontal lobes, providing amazingly even coverage through the crossover point. This extends the VI characteristic down to 500 Hz in an extremely compact enclosure.
The high-frequency horn in the EVI-28 is mounted tilted 15° back relative to the EVI-12 and EVI-15. Along with the polar steering in the woofer’s crossover, this arranges the dispersion for long throws relative to the mounting height. The recommended operational vertical angle is minus 5°from the top surface of the enclosure to minus 45°, defining a maximum used vertical dispersion of 40°. The standard aiming of the system when it
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