Electro-Voice MH4020NC User manual

Description
The Electro-Voice MH4020NC 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.TheMH4020NCcombinestwo
pioneering concepts developed by Electro-
Voice: constant-directivity horns and Mani-
fold Technology®. The MH4020NC’s poten-
tially high acoustic output, stable directional
characteristics, and extended low-frequency
performance make it highly suitable for mu-
sic and speech reinforcement in large indoor
and outdoor venues.
At the heart of the MH4020NC are four
ND10A 10-inch water-resistant drivers. The
driver has been specially developed for the
MH series of horns. It incorporates a unique
diaphragm construction of Kevlar®and ep-
oxy.1This combination of high-technology
materials produces a diaphragm with a
strength-to-weightratioon the order of twice
that of conventional materials.The neody-
mium motor structure produces 3 dB addi-
tional output up to 1600Hz. Each driver is
integrallymounted to the fiberglass horn bell
via a heavy-duty mounting bracket and pro-
prietary Aperiodic EnhancerTM phase plug
(U.S. Patent No. 4,718,517). The Aperiodic
EnhancerTM is responsible for the extended
high-frequency response of the
MH4020NC'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
acousticloadingtomaximizeacousticoutput.
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,oneremains
available. The ND10A drivers are contained
andsealedwithinfiberglasscoversoptimally
tunedformaximumlow-endperfomanceand
displacement control.
The frequencies above 1,600 Hz are handled
by the Electro-Voice HP420 constant-direc-
tivity horn, in combination with a contrac-
tor-selected and installed high-frequency
compression driver.
Ring-Mode Decoupling (RMD™)
The MH4020NC 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 MH4020NC 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 MH4020NC is safely in-
stalled in accordance with all such regula-
tions.
TheMH4020NCisdesignedtobesuspended
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
MH4020NC
Neodymium Driver
Coaxial Stadium Horn
System
• Constant-Directivity Manifold Technol-
ogy®Horn system with 40° X 20°
coveragepattern
• Ring-Mode Decoupling (RMD™)
technology for outstanding intelligibility
and clarity
• Includes four ND10A, 10 inch neodymium
based midrange drivers for 3 dB more
output than with ferrite drivers
• Includes HP420A high-frequency horn and
mountingbracket
• Use EV Neodymium or Ferrite HF drivers,
single or manifolded (HF drivers sold
separately)
• Excellent response down to 100 Hz
eliminates supplemental low frequency
systems in many applications
• Large mouth provides high directivity at
low frequencies
1. Kevlar is a registered trademark of DuPont

MH4020NC MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver Coaxial Stadium Horn System
2
rear of the front flange to aim and stabilize
the device. Electro-Voice recommends that
each MH4020NC be independently sup-
ported. The MH4020NC 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 MH4020NC. In the
worst case (DH2A/4MT) an additional 48 lb
is added. This should be taken into consider-
ation 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 MH4020NC 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 MH4020NC’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 ND10A (6 dB per octave). At lower fre-
quencies, directivity is lost when the mouth
is no longer large enough to maintain direc-
tional control. These two consequences can
be observed in the “humped” response in
Figure 3. Equalization can be easily applied
with a graphic equalizer to give a flat re-
sponse.
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 ND10A drivers in the MH4020NC
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 il-
lustrates 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 se-
lected, the polarity of the drivers must be
considered (see Figure 9 and Polarity of the
ND10A Drivers section).
Directivity
The axial directivity factor Rθof the
MH4020NC 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 MH4020NC’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
MH4020NC 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 ND10A Drivers
For Manifold Technology®to operate cor-
rectly, the drivers must be operated “in
phase.” In other words, for parallel connec-
tion, the ND10A’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 MH4020NC re-
quires service, each ND10A easily can be
replaced or serviced by 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
extramarginofreliability. 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 MH4020NC 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

MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver 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 MH4020NC 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®techniqueshall
be exploited and result in a power-handling
capacityof1,200wattsperEIAStandardRS-
426A. The average axial sensitivity shall be
112 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 MH4020NC.
The horn shall be 1500 mm (59.0 in.) high,
991 mm (39.0 in.) wide, 1880 mm (80.0 in.)
long and weigh 95.4 kg (205 lb).
The horn shall be the Electro-Voice
MH4020NC 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 theindividual prod-
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 theindividual prod-
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 ser-
vice representatives. Obtaining Warranty
Service: To obtain warranty service, a cus-
tomer must deliver the product, prepaid, to
Electro-Voice Service or any of its autho-
rized 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.

MH4020NC MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver Coaxial Stadium Horn System
4
Figure 8—Polar Response
160 Hz 200 Hz 250 Hz
315 Hz 400 Hz 500 Hz
1.6 kHz800 Hz
630 Hz
2 kHz 3.15 kHz2.5 kHz
5 dB per division
HORIZONTAL
VERTICAL

MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver 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)
SPL in dB
5 dB per division
HORIZONTAL
VERTICAL
10 kHz 16 kHz8 kHz
4 kHz 5 kHz 6.3 kHz

MH4020NC MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver Coaxial Stadium Horn System
6
Figure 4—Impedance Response (one
paralleled pair of drivers)
Figure 5—Distortion Response, 10%
Power
Figure 6—Beamwidth Response

MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver 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.)

MH4020NC MH4020NC Neodymium Driver Coaxial Stadium Horn System
MH4020NC Neodymium Driver Coaxial Stadium Horn System
8
HORNS Part Number 534917— 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 HandlingLong term average
broadband per EIA RS-426A, (See
page 3 for complete test description):
1200 Watt
Sensitivity, (Sound Pressure Level @ 1
Meter, 2.83 Volts input,band limited
pink noise in anechoic environment):
112 dB
Average Efficiency:
35%
Nominal Coverage Angle (See figure 6),
Vertical:
40°
Horizontal:
20°
Mid-bass Transducers,
Configuration:
4-way manifoldy manifold
Transducer Complement:
ND10A, neodymium drivers 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 Specification,
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:
95.4 kg (205 lb.)
Shipping Weight:
100.4 kg (216 lb.)
Packing:
Wooden pallet