Electro-Voice DVX Woofers User Manual

David Hewitt

by Alan Babb

T

he DVX Series is the latest
generation of high-performance

woofers from Electro-Voice (EV).
The story begins in spring 2005,
when EV launched its ZX5 as the
“world’s most versatile loudspeaker”:
a 2-way portable powerhouse capa­ble of filling large spaces with con­cert-quality sound, all while weighing
in at less than 50 pounds.

Word spread quickly. The motor
behind EV’s offering was built into the
ZX5’s sleek molded enclosure: the EV
DVX-3150—a brand-new, 15-inch
woofer, based on the all-new DVX
platform. It’s not often that an experi­enced team of engineers is given a
blank piece of paper and asked to de­velop a product that represents the
very best in all aspects, without com­promising on a single detail. With
DVX, that was the mission. The DVX­3150 features an all-new cone and
surround structure for very low distor­tion and high excursion, along with
an all-new frame and motor structure
for high output with very low power
compression.

Having impressed everyone who
heard it in the groundbreaking ZX5,
the DVX concept soon materialized
again in the X-Line Very Compact,
the latest and smallest of the EV

line-array family. Shortly after the
launch of X-Line Very Compact and
its 12-inch DVX-3120 woofer­equipped, XS212-LF cabinet (the sub
element in the XLVC line), the
phone calls began: “The XS212-LF
sounds incredible for its size, with
tons of power. Are these speakers
going to be available in the XLC
medium-sized line-array format?”

EV has always listened closely to
its customers, and these questions be­came the impetus for EV’s engineers
to put DVX at front and center in
their transducer program, the result
of which was the development of a
brand-new, 12-inch LF driver, the
DVX-3121, and a new mid-bass driv­er, the DVN 6.5-inch.

Which brings us up to date. Both
speakers made their debut at Info­Comm 2006 inside the XLC127DVX
3-way, full-bandwidth line-array ele­ment, based on the world-renowned
XLC127+. The DVX-loaded XLC has
all the sonic signatures that made its
predecessor a favorite, but with ex­traordinary power handling and per­formance specs that surpass those on
many full-sized line-array offerings.

So how was all this achieved? Al­low me to explain some of the
“sound innovations” behind the
DVX concept, at the drawing board

stage and beyond. Woofers, like all
loudspeakers, are governed by a
complex melding of disciplines: me­chanical engineering, electrical engi­neering, physics and acoustics. The
DVX line has been optimized in all
of these areas using the latest tech­nologies. First of all, the DVX mag­net structure, the motor that works
with the voice coil to provide the
drive force to the woofer, was opti­mized for strength, stability, travel
and linearity. Nonlinearity in a
speaker’s magnetic field or suspen­sion not only leads to added distor­tion but also greatly impacts the life
expectancy of a speaker.

For example, if you have a speak­er motor that is stronger when the
cone is moving out of the basket
than when moving in, the speaker
will tend to offset itself to the out­side. Since the suspension of the
speaker (the surround and the spider)
can only move a finite distance in ei­ther direction before being damaged,
you are going to stress these compo­nents more in one direction than the
other. It also makes the speaker limit
(stop moving) too quickly in one di­rection, and that means you lose sen­sitivity and increase distortion. To fur­ther compound this problem, the
magnetic field generated by the voice
coil can cause the field of the perma­nent magnet to modulate. This is the

Efficiency and Accuracy By Design

Electro-Voice DVX Woofers

[59]

soundInnovations:

the manufa

cturer’s view

I

started out as a studio engineer
many years ago, but I was

hijacked by a remote truck and
never looked back. The immediacy
and excitement of live music still
captivates me to this day. One of the
most enjoyable things about work­ing in the field with so many differ­ent acts for short periods of time is
the sheer number of great people
you get to meet and work with.

I’ve had the pleasure of hosting
some of the best engineers on the
planet in our remote trucks over
the years. Some of them already
have great chops for live work, and
some have had very little exposure
to the chaos of live work.

What I’d like to do in this article
is encourage everyone to get out
on the road more often. No matter
what your job description might
be, participating in a live show,
even from the sidelines, can be a
real boost to your enthusiasm for
the career you chose.

Especially if you are involved in
post work that has live music con­tent, it behooves you to get out on
location to see how it’s done. This
works to everyone’s advantage be­cause you may be able to impart
some wisdom to the live engineers
about post problems.

There are many ways to do it
right and even more ways to do it
wrong. Besides, it’s fun to see all

the geek gear the video guys bring
to the party. For you studio folks, it
might surprise you how advanced
the audio section is on modern en­tertainment video trucks. It’s amaz­ing how much gear you can pack
in a space 8x8 feet or less. Watch­ing a pro production mixer, like Ed
Greene at the Oscars, handle sever­al hundred inputs and outputs live
to air will make your hair stand up!

Things are generally a little
calmer over in our audio-only re­mote trucks. We usually deal only
with the music elements. Of
course, that may mean 10 bands in
a row! You do have to scramble to
keep up. Our Classic Silver Studio
has the big Neve VR with recall and
Flying Faders snapshots, and that
works well when you have time to
reset. But if you want instant glob­al reset, our new White Truck with
a pair of Yamaha DM-2000s is the
ticket. The Neve works best for
projects like Neil Young’s recent
film, Heart of Gold, and the Yama-
has for TV shoots like Jazz at Lin­coln Center’s Gala, where you have
maybe a dozen different sets.

One of my concerns over the
years has been proper documenta­tion of the media. At Remote
Recording, our trucks are equipped
with software to quickly document
all the relevant information for

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September 2006 prosoundnews.com

Come Out on the Road

sparstech

equivalent of your car motor losing power many
times a second. It would be difficult to have a
smooth, controlled speed ride.

To solve this problem, the woofers in the
DVX line have been optimized via extensive
computer FEA (Finite Element Analysis) to have
linear magnetic fields that do not overly modu­late. With the aid of a laser displacement meas­urement system, we can also optimize the sus­pension to not only have the right stiffness but
also to stop the cone motion in a smooth and
controlled fashion when the speaker is pushed
to extremes. What does all this mean to the
prospective customer? Quite bluntly, it means
less distortion under normal conditions and no
rude noises when the speaker is overdriven.

Another problem common to woofers is
that the voice coil of the speaker, like any coil
of wire, has an inductance. Place a hunk of iron
inside a coil and you get even larger induc­tance. In speaker terminology, we call that
hunk of iron a “pole piece”; every speaker has
one. Most people understand the problems
caused by inductance at high frequencies. Engi-

neers take advantage of inductance all the time
in crossover design. The problem with induc­tance in a speaker is as follows: As the cone
moves outward, it moves out of the magnetic
circuit and the pole piece is no longer inside as
much of the coil as when the cone is moving
inward. This asymmetry in the inductance also
causes an offset of the speaker’s center posi­tion, just like a nonlinear magnetic field or sus­pension. Besides negatively impacting the life
expectancy of a speaker, this asymmetry causes

distortions that are particularly audible and
offensive.

To combat this problem, the DVX woofer
uses multiple approaches. First, we computer­modeled the magnetic structure and optimized
the geometry to eliminate asymmetries. After
the FEA phase prototyping, the tests and meas­urements began. The use of multidimensional

measurements using acoustic and laser data
further sped perfecting the design so we could
very quickly identify areas to improve and the
solutions. This enabled a final design that is far
superior to using traditional design methods.

Unfortunately, you cannot simply eliminate
the pole piece from the equation, so we did the
next best thing. We have put a conductive but
non-magnetic ring inside the magnet structure.
Sometimes called a Faraday Loop, this shorting
ring blocks the field from the coil that would in­teract with the iron core, without affecting the
DC or static field generated by the large ceram­ic magnet of the motor structure. Another ben­efit is that is also counteracts the modulation of
the static field that can be caused by the field
generated by the voice coil.

At the end of the day, of course, all this adds
up to a superior-sounding loudspeaker. DVX goes
to show that there is still room for improvement
in the world of loudspeaker design. It’s not just
about the greater overall output. In DVX, the lev­el of sonic clarity—even for an arena-size system
running extremely high SPLs—is unprecedented.

Alan Babb is a transducer engineer for
Electro-Voice.

For a more highly illustrated version of this
story, visit www.prosoundnews.com and click on
“web bonus.”

many different formats. These days that’s a lot,
and it’s getting increasingly difficult to find a
place to store a paper trail of data. Our techni­cian, Phil Gitomer, insists on having track
sheets and take sheets for every drive or disc.
How many times have you had a hard drive or
tape show up with no documentation? With­out wasting time mounting it and playing the
material, you have no idea what’s there.

Sometimes it’s hard to get accurate infor­mation to document. Rehearsal time for live
shows can be short or nonexistent. Getting ti­tles for classical music movements without a
score, improvisational jazz, or artists and pro­duction people that won’t give up a set list (or
who even change it without telling audio), and
these days, even guns on stage are all elements
that make obtaining this information difficult. I

would be very interested to hear from you post
guys about what you like to see for documen­tation. What happens to the paper documen­tation? Does it get used or tossed? Would you
like to have a CD with the docs on it?

Anyway, back to the theme about getting
more people involved in the production of live
shows and the business of recording them.
One of the ways might be for you to attend a
SPARS meeting in your area. I try to make them
all, gigs permitting. You might just meet some
interesting people and learn something from
their forums. Karen Brinton is more than just
Remote Recording’s boss; she is the current
president of SPARS.

David Hewitt is chief engineer and presi­dent of Remote Recording in New York City.

Membership in SPARS, the Society of Pro­fessional Audio Recording Services, is open to
studio owners, producers, engineers and any­one else involved in professional recording. For
more information, contact the organization at
800-771-7727, or visit www.spars.com.

[66]

prosoundnews.com September 2006

SPARS

(continued from page 59)

Innovations

(continued from page 59)

Graph plotting the variation in the strength of the magnetic field in the motor gap
vs. time, using a DVX motor structure and a conventional ceramic motor structure.
Drive signal: 75V pk at 100 Hz.

The Klippel measurement system is used to measure the symmetry of the magnetic
field, the compliance of the suspension and the inductance.