Electro-Voice MH4020AC User manual

Description
The Electro-Voice MH4020AC is a wide-
range, 40° x 20° mid-bass/high-frequency
constant-directivity horn-and-driver system
utilizing Ring-Mode Decoupling (RMD™).
With a contractor-installed high-frequency
driver, it covers the frequency range of 100
Hz to 20,000 Hz with minimal equalization.
The MH4020AC combines two pioneering
concepts developed by Electro-Voice: con-
stant-directivity horns and Manifold Tech-
nology®. The MH4020AC’s potentially high
acoustic output, stable directional character-
istics, and extended low-frequency perfor-
mance make it highly suitable for music and
speechreinforcementinlargeindoorandout-
door venues.
At the heart of the MH4020AC are four
DL10X-SH 10-inch water-resistant drivers
(U.S. Patent No. 4,547,632). The driver has
been specially developed for the MH series
of horns. It incorporates a unique diaphragm
construction of Kevlar®and epoxy.1This
combination of high-technology materials
produces a diaphragm with a strength-to-
weight ratio on the order of twice that of
conventional materials. Each driver is inte-
grallymounted to the fiberglass horn bellvia
a heavy-duty mounting bracket and propri-
etaryAperiodicEnhancerTM phaseplug(U.S.
Patent No. 4,718,517). The Aperiodic
EnhancerTM is responsible for the extended
high-frequencyresponseoftheMH4020AC’s
mid-band section. It makes use of the fact
that only the apex of the cone (near the voice
coil) is in motion at higher frequencies, and
automatically adjusts the acoustic loading to
maximize acoustic output.
Manifolding allows the output of two or
moredriversto be summed without the usual
detrimental interference problems in the
pass-band. There are a number of additional
advantages to manifolding, including re-
duceddistortion (see Figure 5) and increased
efficiency at certain frequencies. There is
also redundancy built into the system; in the
unlikelyeventofadriverfailure,one remains
available. The DLX10-SH drivers are con-
tained and sealed within fiberglass covers
optimally tuned for maximum low-end
perfomance and displacement control.
The frequencies above 1,600 Hz are handled
by the Electro-Voice HP420A constant-di-
rectivity horn, in combination with a con-
tractor-selectedandinstalled high-frequency
compression driver.
Ring-Mode Decoupling (RMD™)
The MH4020AC controls both acoustical
and mechanical ring modes to provide dra-
maticallyincreasedintelligibility, using tech-
niques learned from the development of the
Electro-Voice X-Array™ concert speakers.
There is much less coloration of the sound
from resonating sources, leaving only the
intended sound to be heard by the audience.
Installation
Suspending any object is potentially dan-
gerous and should only be attempted by in-
dividuals who have a thorough knowledge
of the techniques and regulations of rig-
gingitemsoverhead.Electro-Voicestrongly
recommends that the MH4020AC be sus-
pended in accordance with all current na-
tional, federal, state and local regulations.
It is the responsibility of the installer to
ensure that the MH4020AC is safely in-
stalled in accordance with all such regula-
tions.
TheMH4020ACisdesignedtobesuspended
safely and easily. The integral mounting
brackets at the rear should be used as the
main structural hanging location. There are
also two structural hanging locations on the
MH4020AC
Coaxial Stadium Horn
System
• Constant-Directivity Manifold
Technology®Horn system with
40° X 20° coverage pattern
• Ring-Mode Decoupling (RMD™)
technology for outstanding intelligi-
bility and clarity
• Includes four DL10X-SH, 10 inch
midrange RMD™ drivers
• Includes HP420A high-frequency
horn and mounting bracket
• Use EV Neodymium or Ferrite
HF drivers, single or manifolded
(HF drivers sold separately)
• Excellent response down to 100 Hz,
eliminates supplemental low fre-
quency systems in many applications
• Large mouth provides high directivity
at low frequencies
1. Kevlar is a registered trademark of DuPont

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
2
rear of the front flange to aim and stabilize
the device. Electro-Voice recommends that
each MH4020AC be independently sup-
ported. The MH4020AC can be easily sus-
pended with either the 40° or the 20° cover-
age pattern horizontal. Note: the contractor-
selectedhigh-frequency drivers contribute to
the overall weight of the MH4020AC. In
the worst case (DH2A/4MT) an additional
48 lb is added. This should be taken into
consideration when suspending the system.
Electrical connections can be made using
standard electrical boxes or weather-resis-
tant boxes if used in adverse conditions. The
mounting brackets incorporate a predrilled
flange to aid electrical box mounting.
If the MH4020AC is suspended, it is recom-
mended that the unit be inspected at least
once a year. If any sign of weakness is de-
tected, remedial action should be taken im-
mediately.
Equalization and Subpassband
Protection
The MH4020AC’s mid-bass section exhib-
its typical constant-directivity horn charac-
teristics, i.e., roll-off at the frequency ex-
tremes.Athigherfrequencies,theroll-offap-
proximately matches the power-response of
the DL10X-SH (6 dB per octave). At lower
frequencies, directivity is lost when the
mouth is no longer large enough to maintain
directional control. These two consequences
can be observed in the “humped” response
in Figure 3. Equalization can be easily ap-
plied with a graphic equalizer to give a flat
response.
The high-frequency compression driver can
be equalized with a graphic equalizer or an
EQ module inserted into the Electro-Voice
XEQ-2 (two-way) or XEQ-3 (two-way or
three-way) active crossover/equalizer. The
EQ module should be selected to suit the
particular compression driver and the
HP420A horn (see relevant data sheet). Be-
cause of its use in large arenas, where air
loss can be significant, it is recommended
that the system be equalized “on site” for op-
timum results. The XEQ-3 and the mid-bass
EQ module from the EQMT-2 can be used
toprovidea good starting point for the equal-
ization.
Electro-Voice strongly recommends the use
of a 100-Hz high-pass filter to protect the
driversfromunnecessaryexcursion and ther-
mal stress.
Connections
The four DL10X-SH drivers in the
MH4020AChornhavea nominal impedance
of 16 ohms each and can be accessed indi-
viduallyanddrivenindependently. However,
itis more typical to combine the drivers. Fig-
ure9illustratessome differentcombinations.
It is particularly important to bear in mind
the impedance of any cabling and
specifications of the amplifier before select-
ing a specific combination. Whatever the
combinationselected,thepolarityofthedriv-
ers must be considered (see Figure 9 and
Polarity of the DL10X-SH Drivers section).
Directivity
The axial directivity factor Rθof 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. Directiv-
ity index (Di) was taken over the same fre-
quency range.
Beamwidth
Plots of the MH4020AC’s 6-dB-down total
includedbeamwidthanglesareshowninFig-
ure 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 micro-
phone was placed 6.1 m (20 ft) from the cen-
ter of rotation of the horn which, in turn, was
0.94m(3.08ft)behindthemouthofthehorn.
See Figure 8.
Polarity of the DL10X-SH Drivers
For Manifold Technology®to operate cor-
rectly, the drivers must be operated “in
phase.” In other words, for parallel connec-
tion, the DL10X-SH’s must be connected so
the negative terminals of the drivers are con-
nected together, and the positive terminals
are connected together.
Service
In the unlikely event the MH4020AC re-
quires service, each DL10X-SH easily can
bereplaced orservicedby removing the back
cover and then removing the driver. A ser-
vice data sheet is available from Electro-
Voice.
Power Handling Capacity
To our knowledge, Electro-Voice was the
first U.S. manufacturer to develop and pub-
lish 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 instru-
ment program. The signal contains more
energy at extremely high and low frequen-
cies than typical actual program, adding an
extramarginof reliability. Thetest combines
not only the overall “long-term average” or
“continuous”level—whichourears interpret
as loudness—but also short-duration peaks
which are many times higher than average,
just like actual program. The long-term av-
erage level stresses the speaker thermally
(heat).Theinstantaneouspeakstestmechani-
cal 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, long-
term average levels exist from several sec-
ondson up. The test performed lasts foreight
hours, adding another extra level of confi-
dence.
Specifically, the MH4020AC mid-band sec-
tion is designed to withstand the power test
described in EIA Standard RS-426A. The
EIA test spectrum is applied for eight hours.
The spectrum is obtained by filtering white
noise (a particular type of random noise with
equal energy per bandwidth). The filter ap-
plies 6-dB-per-octave slopes below 40 Hz
and above 318 Hz. When measured with a
one-third-octave constant-percentage ana-
lyzer, this filter produces a spectrum
whose 3-dB-down points are at 100 Hz
and 1,200 Hz with a 3-dB-per-octave
slope above 1,200 Hz. This shaped signal

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
3
is then further filtered with an 80-Hz, 12-dB-
per-octave high-pass filter to prevent out-of-
passband displacement. The amplifier is set
to provide 1,200 watts into the 6.9-ohm EIA
equivalent impedance (91.0 volts). Ampli-
fierclipping sets instantaneous peaks at 6 dB
above the continuous power or 4,800 watts
peak (182.0 volts). During this test, the mid-
band section is not high passed at 1,600 Hz.
The high-frequency section’s power han-
dling is dependent on the selected driver
combination. Please refer to the relevant en-
gineering data sheet.
Architects’ and Engineers’
Specifications
The horn shall be of the constant-directivity
type.Itshallproduce a horizontal beamwidth
(6-dB-downangle)of40°,deviatingnomore
than +20°/–5° from this angle over the range
of 350 Hz to 20 kHz. It shall produce a ver-
tical beamwidth of 20°, deviating no more
than +30°/–5°over the frequency range of
350 Hz to 20 kHz. In addition, it shall pro-
vide an acoustic load to below 100 Hz.
The MH4020AC mid-bass section shall op-
erate over the range of 100 Hz to 4,000 Hz,
with a recommended crossover frequency of
1,600 Hz, and be driven by four 10-inch,
weather-resistant drivers with high-technol-
ogy cones of Kevlar®and epoxy.1The pat-
entedManifold Technology®technique shall
be exploited and result in a power-handling
capacityof1,200wattsperEIAStandard RS-
426A. The average axial sensitivity shall be
109 dB SPL at 1 meter with 2.83 volts ap-
plied. The frequencies above 1,600 Hz shall
be produced by the supplied Electro-Voice
HP420A TransPlanarTM constant-directivity
horn with user-selectable driver combina-
tions.
The horn bell manifold chamber and back
covers shall be constructed of fiberglass,
foam and polyester resin. Two steel mount-
ingrails shall be provided to coaxially mount
the Electro-Voice HP420A horn. The horn
shall have an integral rear mounting bracket
madeofblackpowder-coated10-gaugesteel.
Brackets shall be provided at the front of the
horn to stabilize and aim the MH4020AC.
The horn shall be 1500 mm (59.0 in.) high,
991 mm (39.0 in.) wide, 1880 mm (80.0 in.)
long and weigh 108 kg (237 lb).
The horn shall be the Electro-Voice
MH4020AC coaxial constant-directivity
Manifold Technology®horn.
Limited Warranty
Electro-Voice products are guaranteed
against malfunction due to defects in mate-
rials or workmanship for a specified period,
as noted in the individual product-line
statement(s)below, or in the individualprod-
uct data sheet or owner’s manual, beginning
with the date of original purchase. If such
malfunction occurs during the specified pe-
riod, the product will be repaired or replaced
(at our option) without charge. The product
will be returned to the customer prepaid. Ex-
clusions and Limitations: The Limited
Warranty does not apply to: (a) exterior fin-
ish or appearance; (b) certain specific items
described in the individual product-line
statement(s)below, or in the individualprod-
uct data sheet or owner’s manual; (c) mal-
function resulting from use or operation of
the product other than as specified in the
product data sheet or owner’s manual; (d)
malfunction resulting from misuse or abuse
of the product; or (e) malfunction occurring
at any time after repairs have been made to
the product by anyone other than Electro-
Voice Service or any of its authorized service
representatives. Obtaining Warranty Ser-
vice:To obtain warranty service, a customer
must deliver the product, prepaid, to Elec-
tro-Voice Service or any of its authorized
service representatives together with proof
of purchase of the product in the form of a
bill of sale or receipted invoice. A list of
authorized service representatives is avail-
able from Electro-Voice Service at 600 Cecil
Street, Buchanan, MI 49107 (800/234-6831
or FAX [phone]). Incidental and
Consequential Damages Excluded: Prod-
uct repair or replacement and return to the
customer are the only remedies provided to
the customer. Electro-Voice shall not be li-
ableforany incidental or consequential dam-
ages including, without limitation, injury to
persons or property or loss of use. Some
states do not allow the exclusion or limita-
tion of incidental or consequential damages
so the above limitation or exclusion may not
apply to you. Other Rights: This warranty
gives you specific legal rights, and you may
also have other rights which vary from state
to state.
Electro-Voice Speakers and Speaker Sys-
temsareguaranteedagainst malfunction due
to defects in materials or workmanship for a
periodoffive(5) years from the date of origi-
nalpurchase.The Limited Warranty does not
apply to burned voice coils or malfunctions
such as cone and/or coil damage resulting
from improperly designed enclosures. Elec-
tro-Voice active electronics associated with
the speaker systems are guaranteed for three
(3) years from the date of original purchase.
Additional details are included in the Uni-
form Limited Warranty statement.
For warranty repair or service informa-
tion, contact the service repair department
at: 616/695-6831 or 800/685-2606.
Fortechnical assistance, contact Technical
Support at 800/234-6831 or 616/695-6831,
M-F, 8:00 a.m. to 5:00 p.m. Eastern Stan-
dard Time.
Specifications subject to change without
notice.

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
4
Figure 1—Polar Response 5 dB per division
HORIZONTAL
VERTICAL
160 Hz 200 Hz 250 Hz
315 Hz 400 Hz 500 Hz
1.6 kHz800 Hz630 Hz
2 kHz 3.15 kHz2.5 kHz

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
5
Figure 3—Axial Frequency Response
Mid-Band Section only (1 watt/1 meter)
Figure 2—Axial Frequency Response
(1,600-Hz crossover, 2.96-ms delay, with
broadband equalization)
5 dB per division
HORIZONTAL
VERTICAL
10 kHz 16 kHz8 kHz
4 kHz 5 kHz 6.3 kHz

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
6
Figure 4—Impedance Response (one
paralleled pair of drivers)
Figure 5—Distortion Response, 10%
Power
Figure 6—Beamwidth Response

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
7
Figure 7—Directivity Response
Figure 9—Wiring Diagram
+
+
8 OHMS
(+)
+
+
8 OHMS
(+)
+
16 OHMS
(+)
+
16 OHMS
(+)
+
16 OHMS
(+)
+
16 OHMS
(+)
Figure 8—Dimensions
1,475 mm (58 in.) REF.
975 mm
(38 in.) REF.
1,878 mm (73.9 in.)
56 mm
(2.2 in.)
38 mm
(1.5 in.)
841 mm
(33 in.) REF.
790 mm
(31 in.) REF.
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.
371 mm
(14.6 in.)
274 mm
(10.8 in.)

MH4020AC Coaxial Stadium Horn System
MH4020AC Coaxial Stadium Horn System
8
HORNS Part Number 534919 — 9817
600 Cecil Street, Buchanan, MI 49107
800/234-6831, 616/695-6831, 616/695-1304 Fax
©Telex Communications, Inc. 1998 • Litho in U.S.A.
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
(RMD™)
Nominal Impedance in pass band (See
figure 4):
8 Ohms/ parallel pair
D.C. Resistance:
6.2 Ohms/ each driver
3.1 Ohms/ parallel pair
Available High-Frequency Transducer
Options For HP420A Horn (Contrac-
tor-selected and installed, purchased
separately)
Single Driver:
DH1A, DH2A, N/DYM1, ND5/2
Manifold Drivers:
DH2A/MT, N/DYM1/MT
Manifolded Driver systems:
DH1A/2MT
Construction,
Mid-bass horn:
One-piece black polyester and
fiberglass with fiberglass rib
reinforcement.
High-Frequency Horn:
A special coaxial version of the
HP420A equipped with resonance
decoupling vents, supplied mounted
on two steel rails
Mid-bass Mechanical Protection:
Integral grille-protection screen
built into manifold chamber
Electrical Connections
Driver Input Connections:
Heavy-duty 12-AWG oxygen free
copper cable, unterminated, exterior
grade UV-Stabilized Flexible
conduit
* Specifications meet or exceed AES Recommended Practice for
Specifications of Loudspeaker Components Used in
Professional Audio and Sound Reinforcement Systems (AES2-
1984; ANSI S4.26-1984)
Driver Polarity:
A positive voltage applied to the
positive leads produces a positive
acoustic pressure.
Recommended High Frequency
Crossover Frequency:
1600 Hz
Slope:
24 dB per octave
HF delay:
2.96ms+/-0.3 ms
Mounting,
Hanging Hardware:
Integral black 10-gauge polyester
powder coated steal.
Physical Specifications,
Height:
1500 mm (50.0 in)
Width:
991 mm (39.0 in)
Length:
1880 mm (73.9 in)
Packed Length:
2030 mm (80.0 in)
Weight:
108 kg (237 lb.)
Shipping Weight:
113 kg (248 lb.)
Packing:
Wooden pallet