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
speech reinforcement in large indoor and out-
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.
1
This
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-
grally mounted to the fiberglass horn bell via
a heavy-duty mounting bracket and propri-
etary Aperiodic Enhancer
TM
phase plug (U.S.
Patent No. 4,718,517). The Aperiodic
Enhancer
TM
is responsible for the extended
high-frequency response of the MH4020AC’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
more drivers to be summed without the usual
detrimental interference problems in the
pass-band. There are a number of additional
advantages to manifolding, including re-
duced distortion (see Figure 5) and increased
efficiency at certain frequencies. There is
also redundancy built into the system; in the
unlikely event of a driver failure, 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-selected and installed high-frequency
compression driver.
Ring-Mode Decoupling (RMD™)
The MH4020AC controls both acoustical
and mechanical ring modes to provide dra-
matically increased intelligibility, 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-
ging items overhead. Electro-Voice strongly
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.
The MH4020AC is designed to be suspended
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
