Xds
X-Array™ Double
Subwoofer System
• Unprecedented acoustic output in
a small, lightweight package
• Ring Mode Decoupling (RMD)™
provides accurate transient detail
• EVX-180B woofers
• Enclosure shell matches two
full-size X-Array™ systems
• Optimized for maximum subwoofer
-frequency acoustic output
Description
The X-Array
™
product line represents im-
portant advancements in concert-sound-rein-
forcement technology. The design goals
called for the highest acoustic output capa-
bility with the highest fidelity in lightweight,
compact enclosures that were easy to array.
The development began with a clean sheet
of paper and took an integrated approach.
The individual loudspeaker drivers, horns,
enclosures, rigging hardware and system
configurations were designed from the
ground up specifically for this high-perfor-
mance application.
The Xds is a manifolded, vented-box sub-
woofer system utilizing two 457-mm (18-in.)
woofers in the double-wide X-Array
™
enclo-
sure shell. The enclosure has been optimized
for maximum subwoofer-frequency output.
The two woofers face each other in a mani-
fold chamber at the center of the enclosure.
This manifolding technique (U.S. Patent
Number 4,733,749) increases the acoustic
loading, resulting in increased low-fre-
quency efficiency (at slightly above box tun-
ing) and reduced distortion compared to
conventional direct-radiating designs. The
woofers were designed as part of the Xds
development and represent a step forward
in state-of-the-art loudspeaker design in
terms of high acoustic output with low dis-
tortion and low power compression.
Electro-Voice engineers developed a new
technology dubbed Ring Mode Decoupling
(RMD
™
) to substantially improve clarity and
intelligibility by reducing both linear and
nonlinear resonance modes that color the
sound.
The low-frequency driver in the Xds is the
EVX-180B. An improved version of the in-
dustry-standard EVX-180A high-excursion
467-mm (18-in.) woofer that has distin-
guished itself as an industry standard for
high-power, low-frequency reproduction.
During the X-Array
™
development, the ther-
mal conduction of the motor was improved
and the suspension was redesigned, giving
the EVX-180B even lower power compres-
sion and a longer mechanical lifetime. In the
Xds, the woofers are manifolded in a vented
enclosure optimized for maximized sub-
woofer output from 30-160 Hz with mini-
mized distortion.
Ring Mode Decoupling, (RMD
™
), is a tech-
nique utilized and named by Electro-Voice
to describe a process used to improve sound
quality in loudspeaker systems. RMD
™
of-
fers a solution to a very fundamental prob-
lem. It has long been recognized that two
different loudspeaker systems can sound dif-
ferent even though they both may be equal-
ized to have the same frequency response.
This difference is due to a variety of reso-
nances, or ring modes that color the sound.
Although this ringing may be very low in
level compared to the program material, it is
still audible. The source of these resonances
may be mechanical or acoustical in nature,
or a combination of both. In addition, they
may be linear or nonlinear, resulting in their
character changing with level. Furthermore,
these Ring Modes may be aggravated when
multiple loudspeaker enclosures are as-
sembled into arrays. The result is a colora-
tion that decreases intelligibility and clarity,
with the nature of that coloration varying
with level. Often, the listener perceives that
coloration as imbalance in the frequency re-
sponse, and will attempt to electronically
adjust the system to restore the spectral bal-
ance. However this electronic equalization
has the negative effect of changing the pro-
gram material itself.
Ring Mode Decoupling (RMD
™
) addresses
mechanical resonances with mechanical so-
lutions, and acoustical resonances with
acoustical solutions. In the Xds development,
RMD
™
was applied at every level – to the
individual low-frequency drivers, the low-
frequency enclosure chambers and the inter-
action between multiple enclosures. The de-
sign process included, for example, the driver
