Electro-Voice EVI-28 User Manual

EVI-28

250-Watt Two-Way
Compact Vari Intense
Speaker System

• Ground-breaking advance in single­box utility

• New small-format Vari Intense® horn
for consistant SPL throughout the
room

• DH2010A titanium compression driver

• Dual 8-inch high-power woofers with
amplitude, frequency and delay
shading

• 1400-watt peak, 250-watt long-term
power capacity

• Secure terminal strip inputs

• Compact, lightweight, refinishable,
easy-to-install enclosure with
U-bracket option

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Description

The Electro-Voice EVI-28 full-range loud­speaker is a 250-watt, two-way, high-effi­ciency system featuring a new small-for­mat Vari Intense
(8-inch) direct radiators in a compact
vented enclosure. The EVI-28 combines
patented-Vari Intense
amplitude-, frequency- and delay-shading
techniques in a fully passive system to a
package that is an industry first in perfor­mance, size and cost-effectiveness.

The EVI-28 is intended to be used as a
stand-alone full-range system, but may also
be used as the midbass/high-frequency
component in most multi-way loudspeaker
systems. The primary applications for the
EVI-28 are in smaller rooms, rooms with
lower ceilings than applicable for the
EVI-12 and EVI-15, and as a complemen­tary system for upper balconies and un­der-balcony areas. The system is optimized
for regular throws on sloped floorplans of
approximately 10 to 15 degrees or long
throws on a flat floorplan relative to the
mounting height.

The high-frequency section of the EVI-28
utilizes a new small-format Vari Intense

1. The use of Vari Intense® horns is protected by U.S. patent
#5,020,630.

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horn and dual 210 mm

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technology with

horn driven by the DH2010A one-inch
throat, wide-bandwidth, titanium-dia­phragm compression driver. This driver
uses a unique, convex-drive Time Path
phasing plug structure (U.S. Patent
#4,525,604). The voice coil is coupled to
the diaphragm with EV’s exclusive Reso­nant Drive
and smooths the high-frequency response
and reduces the amount of internal equal­ization for flat frequency response past
25,000 Hz.

EV’s self-resetting PRO
the crossover network to guard the com­pression driver from damage. If input
power to the driver exceeds the nominal
rating, the pro circuit is activated, reduc­ing the power delivered to the driver by 6
dB. The system will remain in this mode of
operation until input power is reduced to a
safe level.

The optimally vented bass section of the
EVI-28 is designed using Thiele-Small
parameters for efficient performance to
below 60 Hz. The dual proprietary 210-mm
(8-inch) high power, long excursion low fre­quency drivers deliver outstanding perfor­mance. The woofers feature a low-mass

®

extended 51-mm (2-inch) diameter voice

TM

technology. This increases

TM

circuit is built into

coil combined with a large magnet struc­ture, a stiff, high-internal-damping cone
and high-temperature materials for years

TM

of reliable performance.
The EVI-28 full-range Vari Intense

speaker 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. Figure 1 has been
averaged and corrected for 1 watt/1 meter.

Directivity

The polar response of the EVI-28 speaker
system at selected one-third-octave band­widths is shown in Figure 2. These polar

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loud-

EVI-28 250-Watt Two-Way Compact V ari Intense

®

Speaker System

responses were measured in an anechoic
environment at 20 feet using one-third-oc­tave pink-noise inputs at 2 degree resolu­tion (over 870,000 data points). The fre­quencies selected are fully representative
of the polar response of the system.
Beamwidth of the system utilizing the com­plete one-third-octave polar data is shown
in Figures 5 and 6. R
index (D

Speaker System

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Constant Directivity and V ariable

) are plotted in Figure 7.

i

and the directivity

θ

Intensity

Constant-directivity systems are specially
tuned to provide a consistent, smooth tran­sition from the low-frequency subsystem
through the high-frequency horn’s oper­ating range. These systems nearly always
have symmetrical vertical dispersion pat­terns and a constant horizontal dispersion
versus elevation. When a constant-direc­tivity system is installed above a surface,
the SPL on the floor varies significantly
from front-to-back and left-to-right. The
front-to-back variation can be minimized
by tilting the horn further back, but this
always results in a large amount of slap
echo, less dynamic range and poor intelli­gibility as a result of excessive energy dis-

EVI-28 250-Watt Two-Way Compact Vari Intense

persed into the reverberant field. The so­lution is Electro-Voice’s revolutionary
patented

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Vari Intense® horn that throws
a 6- to 10-dB hotter signal to the back of
the room while providing a wide nearfield
angle and a narrow farfield angle. The vari­able horizontal angle ensures a rectangu­lar floor pattern, and the intensity change
compensates for the drop in SPL over
the longer distance to the back of the room
(13 feet for the short throw and 55 feet for
the long throw in a typical underbalcony
application such as Figure 7). This single
horn replaces a short-throw/long-throw
horn combination, cutting materials and
labor time while increasing performance
with higher intelligibility and more uniform
coverage. The system is provided with a
2,000-Hz passive crossover featuring
tweeter protection and a proprietary pas­sive equalization circuit that provides fre­quency-shading, amplitude-shading and
time delay to the two woofers. An Acous-

1. The use of Vari Intense® horns is protected by U.S. patent

#5,020,630.

2

tic Lens Filter (ALF) 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.

Installation Tactics

The EVI-28 is designed to provide sub­stantially even SPL over a floorplan of a
size that is determined by the height of the
system above the floor and the vertical aim­ing angle of the system relative to the floor.
The recommended operational vertical
angle is minus 5 degrees from the top sur­face of the enclosure to minus 45 degrees,
defining a maximum used vertical disper­sion of 40 degrees. The standard aiming
of the system when it is mounted above a
flat floor is with the top of the enclosure
parallel to the floor. In this orientation, the
system will provide even SPL over a
floorplan that is approximately twice as
wide as the mounting height, and five times
as long. Tilting the enclosure down by
approximately 10- to 15-degrees relative to
the slope of the floor will produce a floorplan
twice as wide as the mounting height and
approximately three times the depth. At the
standard aiming, the 45-degree nearfield
operational angle defines an approximate
offset to the first useable row of one-half
the height of the speaker system above
the listening plane.

In a typical installation, the top surface of
the loudspeaker will point slightly above
the head height of the furthest targeted
seating or standing area. This will ensure
the minimum amount of slap echo from the
back wall. In an under-balcony situation,
the sharp cutoff above the zero degree axis
prevents early ceiling reflections from caus­ing interference patterns in the listening
area. Since the EVI-28 has a very smooth
and rapid drop-off towards directly below

the cabinet, you can actually stand right in
front of the speaker (see Figure 10) with­out ear strain or microphone feedback. The
remarkable absence of lobes to the rear al­lows the system to be mounted directly
overhead to target a particular area with­out disturbing the audience below or be­hind the cabinet.

For example, Figure 9 shows a typical un­der-balcony application that has a floor
with an upward slope of 5 degrees. The
speaker is mounted 10 feet above the
seated head height, so the horizontal width
is fixed at approximately 20 feet. The en­closure is tilted back by 5 degrees to pro­vide a 50-foot throw, with the outskirts of
the pattern filling in the rear aisle area with
tonally accurate but reduced overall SPL.
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.

Power Handling

To our knowledge, Electro-Voice was the
first U.S. 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-

EVI-28 250-Watt Two-Way Compact V ari Intense

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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. The EIA test spec­trum is applied for eight hours. 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 ap-

propriate power amplifier output rating.

1. To use the EVI-28 to full capacity,
skilled experts in sound-system instal­lation and operation will obtain the
best results if the power amplifier is

2.0 to 4.0 times the long-term average
noise power rating of the speaker
system. For the EVI-28, this is 500
to 1000 watts.

The caution cannot be made strongly
enough, however, that this arrangement
is only for experts or for those who can
discipline themselves against “pushing”
the system for ever-higher sound levels
and who can avoid “accidents” such as
catastrophic feedback or dropped micro­phones.

2. A more conservative, “normal” ampli­fier size, which will produce audible
results nearly equal to those of the
“expert” recommendation, is 1.0 to 1.4
times the long-term average noise
power rating of the speaker. For the
EVI-28, this is 250 to 350 watts.

3. To be very conservative, one can use
an amplifier rated at 0.5 to 0.7 times
the long-term average noise power
rating of the loudspeaker. For the EVI­28, this is 125 to 175 watts.

Request P.A. Bible Addition No. Two
(“Power Handling Capacity”) for more
background on these recommendations.

EVI-28 Connections

Electrical connections to the system are
made by large screw terminals able to ac­cept up to 10-gauge wire, mounted to an
input panel on the back of the enclosure.

Speaker Protection

The EVI-28 like all other vented systems
experiences rapidly increasing cone excur­sion below the box tuning frequency, while
the acoustic output decreases rapidly. To
ensure a long woofer life even when used
at high power levels, it is recommended
that some form of electronics be used to
control unnecessary woofer cone excur­sion.
Graphic equalizers and active crossovers
are two methods that can be used to pre-

vent low-frequency signal below band­pass from going to the loudspeaker. When
using and active crossover, a high-pass
filter with a cut-off frequency of 35- to 50-Hz
will provide the necessary protection. The
filter should have a slope of at least 12 dB
per octave. Such subpass band filters are
found in many crossovers and equalizers
manufactured by Electro-Voice, as well as
other commercially available equipment.

Enclosure Construction and Refinishing

The enclosure is constructed from high­grade void-free 12-mm (0.5-inch) 9-ply and
18-mm (0.71-inch) thick 13-ply birch ply­wood and lined with sound-absorbent cot­ton batting. This high-strength enclosure
is coated with an attractive textured black
or white finish for a truly professional ap­pearance. Systems with unfinished enclo­sures suitable for staining come with a black
grille and may be ordered for a small addi­tional charge. The included 3/8-16 hang­ing points ensure easy installation in nearly
every application. The grille is constructed
from a sturdy 16-gauge medium-gloss black
or white powder-coated steel and may be
painted or covered with cloth to match the
enclosure. If the grille is painted, the acous­tic foam insert should be removed during
painting and reattached with a contact or
spray adhesive on the grille, such as 3M
Super 77. Take extreme care to replace the
foam insert in its original position and pre­vent paint or adhesive from covering the
foam, as it will obstruct the pores and de­grade the performance of the system.

Suspending EVI-28 Enclosures
W ARNING: Suspending any object is po-

tentially dangerous and should only be at­tempted by individuals who have a thor­ough knowledge of the techniques and
regulations of rigging objects overhead.
Electro-Voice strongly recommends that
the EVI-28 be suspended taking into ac­count all current national, federal, state
and local regulations. It is the installer’s
responsibility to ensure that the speaker
system has been safely installed in accor­dance with all such regulations. Electro­Voice strongly recommends that all sus-

EVI-28 250-Watt Two-Way Compact Vari Intense

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Speaker System

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