Electro-Voice xb eds ユーザーズマニュアル

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 Xb is a manifolded, vented-box bass

system utilizing two 457-mm (18-in.) woof-

ers. The two woofers face each other in a

manifold chamber at the center of the en-

closure. This manifolding technique (U.S.

Patent Number 4,733,749) increases the

acoustic loading, resulting in increased low-

frequency efficiency (at and slightly above

box tuning) and reduced distortion compared

to conventional direct-radiating designs. The

woofers were designed as part of the Xb

development and represent a step forward

in state-of-the-art loudspeaker design in

terms of high acoustic output with low

distortion 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 Xb 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

Xb, the woofers are manifolded in a vented

enclosure optimized for maximized output

from 37-160 Hz with minimized 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 offers

a solution to a very fundamental problem. It

has long been recognized that two different

loudspeaker systems can sound different

even though they both may be equalized to

have the same frequency response. This dif-

ference is due to a variety of resonances, or

ring modes that color the sound. Although

this ringing may be very low in level com-

pared to the program material, it is still au-

dible. 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 char-

acter changing with level. Furthermore, these

ring-modes may be aggravated when mul-

tiple loudspeaker enclosures are assembled

into arrays. The result is a coloration that de-

creases intelligibility and clarity, with the

nature of that coloration varying with level.

Often, the listener perceives that coloration

as imbalance in the frequency response, and

will attempt to electronically adjust the sys-

tem to restore the spectral balance. However

this electronic equalization has the negative

effect of changing the program material

itself.

Ring-Mode Decoupling (RMD

™

) addresses

mechanical resonances with mechanical

solutions, and acoustical resonances with

acoustical solutions. In the Xb development,

RMD was applied at every level – to the in-

dividual LF drivers, the LF enclosure cham-

bers and the interaction between multiple en-

closures. The design process included, for

example, the driver cone, suspension geom-

etry and materials, enclosure geometry and

materials, absorptive materials, etc. The re-

sult is a dramatic improvement in clarity and

with a much more neutral sound (a lack of

coloration) with the loudspeaker system

maintaining its sonic integrity from the very-

lowest sound pressure levels to the very-