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. The MH4020NC combines two
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.
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.The neody-
mium motor structure produces 3 dB addi-
tional output up to 1600Hz. Each driver is
integrally mounted to the fiberglass horn bell
via a heavy-duty mounting bracket and pro-
prietary 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
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
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 ND10A drivers are contained
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 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-
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 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.
The MH4020NC 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
MH4020NC
Neodymium Driver
Coaxial Stadium Horn
System
• Constant-Directivity Manifold Technol-
ogy
®
Horn system with 40° X 20°
coverage pattern
• 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
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 frequency
systems in many applications
• Large mouth provides high directivity at
low frequencies
1. Kevlar is a registered trademark of DuPont
