University Training Curriculum

University Training Curriculum
Technology and Materials
Updated: 6.12.14
Mission
The best loudspeaker isn’t the one that gives the most,
it’s the one that loses the least.
- John Bowers
When John Bowers set up his company
in 1966, his ambition was simple, yet
revolutionary. He wanted to create a
loudspeaker that neither added to nor took
away from the music. A speaker capable of
giving listeners nothing more or less than the
true sound of the original recording. In effect,
the perfect loudspeaker.
We’ve been exploring the world of sound
ever since. During that time our technology
has evolved. Our range of products has
expanded. But our mission remains the
same. To bring listeners closer to the sound
artists and engineers intended them to
hear. Whatever we make, we will never
stop pushing at the boundaries of acoustic
performance in pursuit of this goal.
Technology and Materials
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The Tweeter
Diamond Tweeter
Carbon Braced
Tweeter
Double Dome Tweeter
Aluminum Tweeter
Nautilus Tapering
Tubes
Tweeter on Top
Decoupling
The Midrange
Kevlar
FST
Cast Driver
Baskets
The Woofer
Rohacell
Dual Magnet Bass Motor
System
Mushrooms
Anti-Resonance Plug
Paper/Kevlar
Woofers
Dual Layer
Bass Drivers
Flowport
Enclosure
Matrix
Marlan Sphere/Tube
Critically Braced
Enclosures
Curved Cabinets
The Crossover
Simple
Crossovers
Bi-wirable
Tweeter
Purpose of the Tweeter
More than just “highs”, tweeters should provide a
sense of space, an open, clear window to the sound
with effortless dynamics free from compression and
artifacts. Get the tweeter right and all the natural
harmonics of music are vividly lifelike.
Materials used in
Bowers & Wilkins Tweeters
Diamond
A new reference with near perfect
performance and 70kHz extension. Exclusive
to 800 Series Diamond.
Carbon Braced Aluminum
40kHz extension pushes the boundaries
of what is possible with aluminum tweeter
technology. Found in PM1 and CI 800 Series.
Aluminum
Building on decades of experience, our latest
version is now the decoupled double dome
with a breakup frequency of 38kHz. Found
in 600 Series, CI 600 Series, CM Series,
Panorama 2, Wireless Music Systems, AM-1.
Diamond Tweeter
Technology
Benefit
The ideal tweeter dome
remains rigid, exhibiting
perfectly piston-like behavior,
as far up the frequency scale
as possible. Best for this are
materials with a high stiffness
to density ratio - which is
where diamond comes in.
The most pristine, crystalline
high frequencies that you’ve
ever heard with an incredible
sense of space and imaging.
Diamond tweeters have
an unprecedented 70kHz
breakup point. It results in
vanishingly low distortion in
the human hearing range.
Found exclusively in 800
Series Diamond.
Watch the video
Diamond tweeters sound more
effortless, yet more detailed
and have a more realistic
sound stage than a standard
aluminum tweeter.
Carbon Braced Tweeter
Technology
Benefit
The Carbon Braced Tweeter uses a ring of
ultra-thin wound carbon fiber to brace the
tweeter dome, raising the breakup of the
aluminum dome to 40KHz, which has a
dramatic effect on the audible frequencies
below 20kHz.
Sparkling, clear highs.
Tremendous sense of
dimensionality and vividness.
Moves near-diamond
performance to more affordable
price points.
A new surround material is used to
provide wider dispersion at higher
frequencies. Doing this makes the
harmonic structure of instruments and
voices more consistent with the angle
of listening and enables the listener to
pinpoint the position of the performers
with greater accuracy and stability.
Found in
• PM1
• CI 800 Series
Double Dome Tweeter
Technology
Benefit
Our newest tweeter combines two dome
layers to push the breakup frequency from
30kHz to 38kHz. This is achieved by reinforcing the outer edge of a 35µ thick aluminum
dome with a 50µ thick aluminum ring. The
additional mass is tiny, while the improved
linearity is huge.
Found in
• CM10
• 600 Series
Main tweeter dome
A second aluminum layer
replicates the main dome’s
profile with the center cut
out. This circular girder
section raises the breakup
frequency and delivers
cleaner sound than a
standard aluminum dome.
The new tweeter delivers
purer, more spacious treble
performance than ever before
for a model in this price range.
Aluminum Tweeter
Technology
Benefits
Our light and rigid design offers great
pistonic performance at an unbeatable
price. Recent innovations such as
a ‘crowned’ voice-coil bobbin and
a copper-plated pole piece extend
performance to 30kHz.
Pure high frequencies with
ultra-low distortion translates
to a greater sense of space and
compression free dynamics.
Found in
•
•
•
•
•
•
•
•
•
CT 800 Series
CM Series
600 Series
CI 600 Series
AM-1
M1
Panorama 2
Wireless Music Systems
MM-1 Computer Speakers
Nautilus Tapering Tubes
Purpose
Benefit
As a consequence of moving air,
every driver creates a front and rear
radiating wave in equal proportions.
While the front wave creates the
music we hear, the rear radiating
wave creates harmful distortion
through phase cancellation. Originally
developed for the Nautilus, this
technology removes the rear wave
of the driver by absorbing energy
in a mathematically derived inverse
horn. A more recent innovation is the
swirl tweeter housing which brings
the tapering tube benefit to more
compact speaker forms, used in
several architectural models.
With the distortion-causing
rear wave energy removed,
all you hear is the pure sound
radiating from the front of the
driver.
Found in nearly all tweeter
applications.
Watch the video
Nautilus tapering tubes
Swirl tweeter housing
Tweeter on Top
Purpose
Benefits
Tweeter on top technology has two benefits. It avoids the
situation with normal cabinet construction, where sound
waves from the tweeter not only radiate towards the listener
but also travel along the baffle surface towards the cabinet
edges. When sound waves meet sharp cabinet edges they
re-radiate (a process known as diffraction) and, due to the
time delay, interfere with and time-smear the sound coming
directly from the drive unit. Having the tweeter separate
from the main cabinet also allows its time-alignment with
the midrange driver to be finely adjusted so the two outputs
add perfectly in phase through the crossover region.
The ‘tweeter on top’ gives you
enhanced soundstage depth
and a much wider sweet
spot. You’ll hear the most
convincing three dimensional
performances ever and pure,
sparkling high frequencies.
Found in
•
•
•
•
800 Series Diamond
PM-1
CM10
CM6
Decoupling
Technology
Benefit
Mechanical vibrations in the cabinet
created by bass drivers result in
distortion when they effect tweeters
or midrange drivers. Decoupling
physically disconnects tweeters and
midrange units from the cabinet with
a synthetic gel barrier, dramatically
reducing this form of distortion.
Purer sound with better focused
and more stable images in the
sound stage.
In baffle-mounted
applications, a ring of
synthetic gel surrounds
and cushions the magnet
assembly, ensuring the
entire assembly is able to
float within its mounting.
Found in
•
•
•
•
•
•
800 Series Diamond
CT 800 Series
PM-1
CM Series
600 Series
CI Series
In tweeter on top designs,
the tweeter is decoupled
from it’s enclosure and the
enclosure is decoupled from
the bass cabinet using gel
components.
The Midrange
Purpose of the midrange
The midrange is responsible for
the most significant part of the
audible sound spectrum. It is
where the real musical action is
invariably found, the “timbre” or
unique tonal character of every
instrument; and perhaps more
importantly, the human voice.
A smooth midband is an
invaluable loudspeaker quality.
Kevlar
The Material
Benefits
Kevlar is a synthetic aramid fiber,
manufactured by DuPont®, and probably
best known for its use in bulletproof vests.
Indeed, those same mechanical properties
of strength and the ability to dissipate the
energy of a bullet also have benefits for
speaker cones.
The most natural and vivid
sounding singers and
instruments that you’ve ever
heard.
Kevlar’s unique woven pattern, when
treated with just the right resin mix
allows standing wave energy to selfcancel. Conventional cones are made of
homogenous materials and tend to have
pronounced resonances - colorations we
hear distinctly. Our Kevlar cones also
behave like smaller cones as frequency
rises, giving smooth dispersion over a
wider area. Kevlar is found in nearly all
Bowers & Wilkins products.
Watch the video
Not only does Kevlar deliver
cleaner sound, it can do so to
a wider group of listeners.
Historical note:
Bowers & Wilkins pioneered the
use of Kevlar as a cone material
back in 1976 (with the DM6 speaker) and
have improved on its application since.
FST Fixed Suspension Transducer
Technology
Benefits
Our famed midrange drivers do not have an
attached surround - they literally float, resting
only gently on a foamed polymer ring which is
matched exactly in mechanical impedance to
the cone. Traveling wave energy up the cone
is simply absorbed by the foamed ring, not
reflected back into the cone. Conventional
rolled surrounds move out of phase with the
cone material at various frequencies, and
have their own resonant frequencies, causing
distortion of critical midrange signals.
Pure instrumental and vocal
tonalities, effortless dynamics
and freedom from dynamic
compression equals stunning
realism.
Found in virtually all our three way designs.
800 Series Diamond, CI 800 Series, CI 700
Series, CT 800 Series, CM8/9/10/C2 and even
the affordably priced 683.
Watch the video
FST maximizes the effects
of Kevlar by improving cone
response times and integrity of
sound transmission. It offers
us the cleanest midrange
performance in the business.
Cast Driver Baskets
Technology
Benefits
The very open design of our cast baskets
greatly reduces air turbulence and
mechanical reflections, both of which add
to the cone’s motion in the form of audible
distortions. Casting a basket hugely
increases strength over the cheaper
alternative-stamping. This results in more
energy transferred to the air.
Midrange that is detailed and
dynamic, free from distortions
that impose an artificial character
where our hearing is most
sensitive.
Found in
• 800 Series
• PM1
• CM Series
• 600 Series
• CI 800 Series
• CI 700 Series
• CCM 663/662, CCM683/682, CWM 663
The Woofer
Purpose of the woofer
The woofer provides that all-important lowend ‘drive’ and ‘punch’.
Bass is literally the foundation of sound. It
provides the power and the scale in a musical
performance, the rhythmic underpinning, not
to mention the dramatic special effects in
many movies. Bass is visceral. It can literally
shake the room, and your emotions! And it
is also crucial to helping create a sense of
space even when overt bass notes are not
present.
Rohacell®
The Material
Benefits
Rohacell’s unusual combination of very low
weight and very high resistance to bending
stress make it the ideal choice for the
structural heart of a bass driver.
For speed, stiffness and
unshakable bass, Rohacell is
the bottom line.
Rohacell is a sophisticated composite
construction having a hard foam core,
sandwiched between carbon fiber skins. It’s
the kind of material normally used for aircraft,
rockets and performance cars’ bodies. So
high air pressures are definitely not a problem.
Rohacell comes closest to the idea of perfect
pistonic behavior and is also very well self
damped to avoid ringing or creating sounds of
its own. Lastly, it very effectively blocks internal
sounds from getting out.
Found in 800 Series Diamond, CI 800 Series,
CT800 Series, and DB-1
Watch the video
The Rohacell cone is
as light as possible for
maximum agility, but
absolutely rigid in order to
retain its shape as it pumps
in and out. Bass is deep,
powerful and free from
distortion.
Dual Magnet Bass Motor System
Technology
Benefits
Powerful bass requires vastly greater
movement than seen in tweeters and
midrange drivers. A conventional woofer
uses a single large magnet. As the voice
coil moves in and out, the magnetic field
becomes asymmetrical, increasingly
so at louder levels. Our dual magnet
design uses two smaller but very
powerful magnets that both face the
top plate, but from opposite sides
and are magnetized in opposition to
one another. This keeps the magnetic
field symmetrical even when the bass
goes very low and very loud.
Much lower bass distortion
at high levels, cleaner more
tuneful bass at all volumes.
Found in
• 800 Series Diamond
Dual Magnets are highlighted in orange.
Mushroom Construction
Purpose
Benefits
Our bass drivers use a
‘mushroom’ type diaphragm
construction, maximizing rigidity
by bonding the cone, dust cap
and extended voice coil bobbin
into a stiffening girder-like unit.
Delivers bass ‘drive’ and ‘punch’
like you’ll hear at a live concert.
Found in
• 800 Series Diamond
Mushroom construction
maximizes rigidity
Watch the video
Anti-Resonance Plug
Technology
Benefits
Unlike the majority of dust caps, the
mushroom-shaped anti-resonance
device is a tight fit inside the voice coil
bobbin. Constructed from polymer foam,
it soaks up resonance like a sponge
while also reducing cone breakup.
The Anti-Resonance Plug
minimizes sound overhang
through a reduction in cone
break up. The voice coil bobbin
flexing is dampened to mellow
the upper frequency response
of the driver.
The stiffness and resistance properties
of the EVA polymer are adjusted to damp
down the tendency of the coil former to
go out of round under the influence of
cone break-up modes.
Creates unparalleled clarity and
detail in the midrange.
Damp the flexing of the bobbin and you
in turn reduce the cone break-up.
Found in
• PM1
• CM Series
• 600 Series
• CI 800 Series
• M1
• A5
The mushroom-shaped Anti-Resonance
Plug soaks up resonance and reduces cone
breakup.
Paper/Kevlar Woofers
Technology
Benefits
Paper/Kevlar cones were developed to
provide many of the acoustic benefits of
Rohacell at a more affordable price point.
You will hear improved bass and
midrange performance with less
veiling of instruments compared
to traditional materials.
Paper/Kevlar drivers provide improved
strength and efficiency. They also reduce
surface bending waves compared to
straight paper or plastic type bass/
midrange drivers.
Found in
• CM Series
• 600 Series subwoofers
• CT8.2
• CT 700 Series subwoofers
• CCM7.3
• CWM7.3
• ISW3
• ISW4
Dual Layer Bass Drivers
Technology
Benefits
Dual Layer aluminum drive units are
reinforced around their periphery with a
second layer of aluminum. The result is
a more effectively damped cone with a
higher breakup frequency. This new
construction technique shifts the
breakup frequency of the driver from
4kHz to 5.5kHz, which allows for a
higher crossover point to the midrange
for better integration.
Ensures a richer, distortion-free
bass response and improved
integration with the midrange.
Found in
• 683 and HTM61
Flowport™
Technology
Benefits
Bowers & Wilkins’ Flowport minimizes
port turbulence in the same way as
a golf ball. Dimples on the surface
generate tiny eddy currents over which
air can flow smoothly and, above all,
silently.
You’ll hear clear, clean bass,
even at high volumes.
Found in
• 800 Series Diamond
• CT800 and CT 700 Series
• PM1
• CM Series
• 600 Series
• CI 800 Series
• CI 700 Series Wall models
• Panorama 2
• Zeppelin Air and Z2
• A7 and A5
Watch the video
The Enclosure
Purpose of the enclosure
A speaker needs a structure to hold all the
elements. It also needs a defined volume
of air to optimize the drivers. In short, it
needs an enclosure. That enclosure should
not have a sound of it’s own. The ideal
enclosure is perfectly inert and therefore
non-resonant. It should focus the sound
only in the forward direction, minimizing
edge reflections.
Matrix™ Bracing
Purpose
Benefits
Matrix interlocking panels take
cabinet bracing to the ultimate level.
This three-dimensional honeycomb,
interlocking structure creates a
rock solid enclosure immune to the
tremendous pressure created by bass
drivers.
If the cabinet is vibrating, it
is making a sound of it’s own.
Offering a dramatic cut in the
level of cabinet coloration, Matrix
allows you to focus on where the
performers are, rather than being
aware of where the speakers are.
Found in
• 800 Series Diamond
• PM1
• CT 800 Series
• CI 800 Series
Watch the video
Marlan® Sphere/Tube
Purpose
Benefits
Crafted from inert Marlan
composite, the internal cavity – a
sphere closely coupled to a short
tube - absorbs most of the sound
from the back of the driver, with
the fibre filling mopping up the
last vestiges. The teardrop shape
smoothly disperses the sound
around the speaker creating a solid,
three-dimensional image.
Incredible clarity with equally
stunning imaging. An “out of the
box”, fully immersive experience.
Found in
800 Series Diamond
Watch the video
Curved Cabinets
Purpose
Benefits
In Bowers & Wilkins curved cabinet
designs, enclosures are bent under
great pressure by purpose built
machine tools. This technique
preserves the wall strength even before
the Matrix structure is fitted. Less
refined curved enclosures used by
other manufacturers often compromise
the wall strength, actually increasing
resonances (a “barrel effect”).
You’ll enjoy the beauty and
sound of your music, uncolored
by cabinet resonances.
Found in
800 Series Diamond
Watch the video
Critically Braced Enclosures
Purpose
Benefits
Resonance is the enemy of good
sound. Even our less expensive models
undergo detailed enclosure testing and
are thoroughly braced to avoid panel
resonances.
Surprisingly uncolored
sound even in our most
affordable speakers.
Found in
All Bowers & Wilkins cabinets
that do not use Matrix Bracing
techniques, have critically braced
enclosures.
The Crossover
Why it matters
Without a crossover, all you’d hear is a
cacophony of uncoordinated sound. All
drivers are designed to specialize in the
reproduction of a narrow range of sounds.
The crossover takes the entire electrical
signal from the amplifier, and divides it up
to match the needs of each driver. The best
crossovers seamlessly blend the sound of
all drivers for perfect harmony like a great
conductor.
We carry out exhaustive listening tests
rigorously assessing the performance of
each crossover component until we find the
optimum component for each position in the
circuit. Fine-tuning by ear is only possible if
the crossover is simple and the section of
the crossover that perhaps benefits most
from our policy of listen-and-learn is the
part handling the signal for the tweeter. In
most Bowers & Wilkins speakers, it is carried
by a single, ear-chosen component that
preserves the very finest detail.
Simple Crossovers
Purpose
Benefits
Our goal is to utilize the widest bandwidth,
lowest distortion drivers possible, which is why
we develop our own custom drive units. As a
result, we can use relatively simple crossovers
where the focus is on exceptional quality and
maximum signal flow.
A sonic picture woven out
of whole cloth that is utterly
transparent and coherent. You’ll
hear more of what comes directly
from your amplifier, and less of
what happens after an inferior
crossover gets its hands on the
signal.
The sonic magic of our designs has much
to do with fine-tuning by ear, which is only
possible if the crossover is simple and the
section of the crossover that perhaps benefits
most from our policy of listen-and-learn is the
part handling the signal for the tweeter. In most
Bowers & Wilkins speakers, it is carried by a
single, ear-chosen component that preserves
the very finest detail. This is a painstaking
process guided by the long experience of our
engineering team.
Watch the video
Bi-wirable
Purpose
Benefits
In bi-wiring, each loudspeaker has
two pairs of terminals. Each pair
of terminals are connected to the
amplifier independently. One cable for
the high frequency/tweeter driver and
one for the low frequency driver.
Bi-wiring separates the signal
paths to each section of the
speaker and can improve
both stereo imaging and detail
resolution. You will hear clearer
high frequencies and a better
sense of space and detail.
Bi-wiring separates the large back
Electromotive Force, caused by the
woofer’s motor system from the smaller
high voltages of the high frequency
section.
It also enables the use of
different types of cable for each
frequency band.
Found in
• 800 Series Diamond
• CM Series
• 600 Series
• CI 800 Series
• CT 800 Series
Conventional connection
Bi-wire connection
(terminal links removed)