Read the July 2015 Voice Coil Magazine article.

Read the July 2015 Voice Coil Magazine article.
Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to, call 800-269-6301, or e-mail
US Enclosure: A Revolution
in Loudspeaker Cabinets
By Brian “JB” O’Neill
(US Enclosure Company)
ince 1990, US Enclosure Company has developed
a series of purpose-engineered composite wall
materials specifically for loudspeaker cabinets that meet
or beat the acoustic qualities of MDF, plywood, plastics,
or metals at the same wall thickness. An added benefit
is OEM loudspeaker companies can visually stand out
from their competition with custom-shaped complex
curved cabinets with Class-A finishes in the same cost
bracket as a basic wooden box cabinet. This technology
can provide an important opportunity for improved
market share, margins, or profits to OEM loudspeaker
manufacturers. The technology is also useful wherever
higher sound clarity (extreme cabinet damping) is
required, from home loudspeaker systems to recording
studio and mastering monitors to headphones to
concert reinforcement, from auto to distributed sound
to turntable bases.
Company Background and Achievements
Since 1990, US Enclosure has amassed an impressive
list of commercial firsts: composite cabinet wall
material designed to perform better than wood; 36”
diameter carbon-fiber braced spherical loudspeaker
enclosures (possibly the largest ever produced); and
the largest egg-shaped loudspeaker enclosures ever
sold. Other examples of unique cabinet shapes include
curved wing-shaped cabinets housing two-way ported
loudspeakers (see Photo 1), multidriver parabolic eggshaped enclosures, and the first spherical enclosures
with egg-shaped interiors both ported and sealed.
From 1996 to 2002, the company developed a full
line of THX compliant home-theater curved loudspeaker
enclosures including: mains, center-channel, ceiling or
wall mounted di-pole rear channel, and subwoofers.
Thiele-Small (T-S) parameters won’t get a blank stare
from this cabinet manufacturer.
Company policy does not allow us to disclose OEM
loudspeaker client names. However, the following non
loudspeaker companies have utilized US Enclosure:
Boeing, Circus Circus Casino, Columbia and Princeton
universities, Cirque du Soleil, Ericsson (of Sweden), and
Dolby Labs both for loudspeaker enclosures for anechoic
sound chamber calibration.
Products and Services
US Enclosure’s Design division can use client-provided
drawings, contractor provided cabinet design drawings,
Photo 1: Here is an example of a curved wing-shaped
enclosure manufactured by US Enclosure.
or speaker stand design and fabrication for virtually any
style cabinet. Custom-shaped cabinets can resemble
a vase, a sculpture, a building, or a headphone. Sizes
for elliptical shapes up to 4,190 ft3 and cubical up to
8,000 ft3 (20’ × 20’ × 20’). Spherical-, egg-, wing-,
and parabolic-shaped cabinets can be constructed up
to 240” long.
The company’s “Loudspeaker Cabinet Design Studio”
page on US Enclosure’s website (
features more than 140 rough but thought-provoking
cabinet shapes, which can be manufactured using the
company’s process. The goal is to encourage creative
thinking for various loudspeaker cabinet shapes, both
curved and box-shaped, which would be difficult to
achieve using wood or other materials. Posted as a
starting point, the company expects clients to modify
the shapes to their needs.
There are several key employees at US Enclosure.
Among them is Kris Metaverso. He is responsible for
engineering/manufacturing material developments. His
20 years of experience and two engineering degrees are
buffered into understanding loudspeaker enclosures. His
previous background includes engineering and materials
development at United Technologies.
D.S. Ragsdale has 15 years’ experience as Vice
President, Operations, and Quality Control for the
company’s subcontractor. Ragsdale has comprehensive
composite manufacturing and estimating experience and
an engineering degree. He also provides a fundamental
knowledge of the requirements needed to take a
potential job from concept or engineering drawing to
completion. Previously, Ragsdale was an engineer
at Western Digital (Hard Drives). He also has been
involved with Engineering Contract-Project Management
for companies such as Disneyland, BD Medical Disposal,
Burger King, Rainbird, and an electrical utility company
named Western Montana. His father, Michael Ragsdale,
advises the company and is an inventor/consultant
with more than 40 years of experience installing,
designing, and manufacturing home and professional
audio products. Michael Ragsdale has designed products
for several companies including Associated Sound
Systems, Altec Lansing, AT&T, Audio Logic, British
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Sound Reproduction (BSR), James B. Lansing (JBL),
PicturTel, Uni-Sync Professional Audio Products (Trouper
Series), United Recording Electronics Industries (UREI),
and Vidicom.
Cabinet Materials
Why composites? Composite fabrication has an
illustrious role in human civilization, and has many
applications where sound, vibration, and strength
are key issues. US Enclosure has developed the
best loudspeaker enclosure materials available and
the material formulations are adjustable so cabinets
can be mass-manufactured to its customer’s exact
US Enclosure’s cabinet wall composites are
specifically engineered for improved loudspeaker
cabinet performance. These composites are based on
several material dampening concepts as well as (among
other factors), density, Youngs Modulus/Modulus of
Elasticity, various tensile strength ratings, and Poisson’s
ratio. The original material, developed by Metaverso in
1992, is named MultiModulus. Ragsdale then developed
the Harmonic Dampening Material. Both materials use
elastomers and up to six additional components to
create encapsulated constrained boundary layers inside
each component constrained boundary layer.
Enclosure wall densities can vary from 20 to more than
150lb/ft3 as determined by the application. The highest
available density is well over twice the density of an
MDF or Baltic birch materials. The walls are waterproof
and comprised of up to 50% recycled materials, and
can additionally be dyed during manufacture or painted
afterwards with Class-A automotive finish levels. The
walls can also be textured during manufacture to
resemble wood, leather, or nearly any other material.
MDF and plywood are moderately good cabinet
materials as both are constructed with glue and have
a somewhat different overall modulus than the primary
wood component. Nonetheless, neither material was
engineered specifically for loudspeaker cabinets.
Furthermore, they are expensive when producing
complex curves. They can also exhibit a series of strong
resonances without substantial bracing.
US Enclosure’s cabinets are mold produced and strive
for no more than two piece cabinets—standard box
cabinets have a minimum of six pieces. Fewer vibrating
panels have obvious benefits for sound quality. Curved
enclosures have the added benefit of a stronger wall
than the same material used in a flat-shaped wall.
These composites have been developed over the last
25 years to be effective and are fully tested to surpass
accelerometer knock-tests and sound and vibration
absorption tests compared to aluminum, other metals,
all woods, concrete, and all plastics at the same wall
thickness. Yet, the overall manufacturing cost is about
the same as standard wooden cabinets.
These accelerometer-based tests used similar sized
actual cabinets without drivers, electronics, or stuffing.
JULY 2015 9
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Figure 1: This accelerometer .wav file compares US Enclosure’s composite material to
different thicknesses of MDF.
The Knock-Test utilized a weighted ball dropped at
an equal distance to measure the vibration in joules
as a function of time (see Figure 1). The Frequency
Response Test was created with an 8-to-3,000-Hz
sweep with the driver sealed on the main driver with
the cutout face inward (see Figure 2). In both cases,
the accelerometer was on the back wall of the cabinet.
Unlike other quality cabinet wall material, US
Enclosure’s wall materials can be easily and costeffectively mass manufactured into any complex curved
shape. This enables a loudspeaker manufacturer to
avoid acoustically damaging transitions (e.g., edges
and slots) in the loudspeaker cabinet as the transitions
behave as acoustical sources following the primary
wave in time and often reversed in polarity. With careful
design of a cabinet’s internal shape, the enclosures can
reduce reflective bleed-through from the interior of the
loudspeaker enclosure through the loudspeaker cones.
Curves and Other Shapes
The optional opportunity for enclosures to have
complex curves allows for unique-looking or décorfriendly cabinets, which differentiate the products from
the competition and provide a true corporate identity
at a cost similar to wood cabinets. An additional
opportunity of lowering diffraction can improve products
sales, while maintaining all the positives associated with
competitive enclosure materials.
Because any shape can now be produced, US
Enclosure enables loudspeaker companies to have new,
Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to, call 800-269-6301, or e-mail
Figure 2: The
of near-field
of plastic
is shown
with and
without US
JULY 2015 11
Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to, call 800-269-6301, or e-mail
fresh looking products in consumer-accepted shapes.
Companies can use existing drivers and electronics in
curved cabinet shapes, many times without crossover
adjustments. In some highly curved shapes, crossover
modifications may be required.
Metaverso points out “Dr Harry Olsen in the 1930s
did the first measurements, which showed curved
loudspeaker cabinets reduce diffraction effects when
compared to other shaped cabinets, as seen in Figure 3.
Properly implemented, your products nearly disappear
from the acoustic soundstage even when the system
uses very inexpensive drivers.”
US Enclosure Manufacturing Facility
Located minutes from Ontario International Airport,
US Enclosure’s manufacturing facility has the benefits
of low-cost production runs and nearly unlimited design
possibilities, with highest quality products at the lowest
possible cost. And, the company’s equipment is among
the largest in US (see Photo 2). US Enclosure’s
manufacturing role is engineering support and dedicated
production management as well as working with
clients to migrate existing products to the superior
cabinet materials using existing shapes or help develop
and manufacture new complex curved or otherwise
unavailable cabinet shapes. US Enclosure’s CADsupported programs supported range from Audocad and
Solidworks to Dassault Systems Catia. IGES files are
also supported. Drawings can be adapted for fasteners
Figure 3: Frequency response variations from different
enclosure shapes, as shown in Harry Olsen’s article
“Direct Radiator Loudspeaker Enclosures,” Journal of the
Audio Engineering Society (JAES), 1951.
Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to, call 800-269-6301, or e-mail
and connectors as well as for ports. Prototyping via
in-house 3-D printing is also available.
Economy-of-scale is achieved at the state-of-theart facility in Ontario, CA, housing 300,000 ft2 and an
additional 100,000-ft2 facility in North Hollywood, as
both offer advanced manufacturing and warehouse
space with the capability to deliver to virtually any
destination in the world via the logistics department. This
ensures that products arrive to their destinations safe
and on time. Additional company departments include:
quality control, assembly, fulfillment, packaging, and
warehousing (see Photo 3).
Manufacturing Capabilities
The plant produces relatively inexpensive tools for
both small and large parts especially compared to other
processes. Various shapes, from simple to complex, can
be made at the same time for quick and economical
prototypes, short production runs, and for high-volume
production. In-house, a tooling department and custom
wall formulation department keeps costs low. Image
embossing or color graphics can be embedded into the
wall material to help defeat product counterfeiting.
As Ragsdale explains, “The process begins when a
client either provides a drawing or asks for US Enclosure
Design to create a shape based on the client’s desire.
For provided drawings, phone discussions immediately
occur. Any element in the specification that has an
issue is discussed and a workaround created. Also,
Photo 2: This is US Enclosures’ manufacturing facility in
Ontario, CA.
US Enclosure provides suggestions for cost savings
during manufacturing. Once a design is approved by
the client, a production mold is produced. No-cost
test cabinets are produced and shipped to the client
until the cabinet meets the client’s needs and desires.
Then manufacturing occurs. US Enclosure provides
storage at no cost up to one year after production and
will execute the client-specified product releases to all
Dayton Audio MCWA60 Full-range Class D Plate
Amplifier with Wi-Fi and Bluetooth 4.0 (with aptX®)
• Create or retrofit self-powered multimedia and
monitor speakers
• Wi-Fi and Bluetooth 4.0 connectivity plus optical,
RCA, and 3.5 mm inputs
• Fully featured wireless remote for simple,
convenient operation
• 2 x 30 watts of Class D power per channel and
only 4.5" wide x 6.25" high
Distributed By:
Visit to see
more and to receive a special offer
725 Pleasant Valley Dr.
Springboro, OH 450666
JULY 2015 13
Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to, call 800-269-6301, or e-mail
Photo 3: This is US Enclosure’s warehouse and QC area at its Ontario, CA, facility.
locations the client desires.”
“Tooling can be designed for less than 1,000 units
or up to 75,000 units before tool rehabilitation. Postprototype quantities begin at 50 units and plant capacity
is more than 1,000,000 million units per year total,”
Ragsdale added.
For more information, visit;
email Brian O’Neill at;
write to 2135 North San Antonio Ave., Upland, CA
(US) 91784; or call 909-851-2273. VC
About the Author: JB O’Neill has 25 years of outside
sales experience. After college, he worked for an audiovideo production company directly associated with
MTV Networks. This company concurrently is a fullblown recording studio, which recorded live albums for
artists such as David Bowie. He also has five years of
experience as a radio on-air/producer.
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