Some engineering problems take longer to solve than
others. Inventors struggled for decades to find the
right filament material, before Thomas Edison tried
carbon and made a practical light bulb.
Photo: Bruce Osborne
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Eureka: How can wood be made pliable enough to form
into loudspeaker cones? That question stumped
engineers for decades until Satoshi Imamura
discovered the answer: rice wine.
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Toshikatsu Kuwahata, an engineer at the audio factory
of JVC (Victor Company of Japan Ltd.), in Yokohama, is
no stranger to such lengthy struggles. He wrestled for
more than 20 years with his own personal
challenge—making a speaker cone that could be
manufactured in quantity out of wood.
The cone is the part of the speaker that vibrates to
produce sound. It is typically made out of paper pulp,
polypropylene, polyester, or some similar pliable
material. But wood, Kuwahata knew, has qualities that
could make it a superior choice for sound reproduction.
For one thing, sound propagates very quickly through
wood, which means that the speaker can produce a wide
range of frequencies. Wood also has an internal damping
effect, which leads to a smoother frequency response.
This is one of the main reasons that wood remains a
popular material for musical instruments.
But unlike the parts of an instrument, the material
used for a speaker cone must be severely deformed to
form the required shape. And when Kuwahata tried to form
the cone out of wood, even thin sheets of wood, it cracked.
He thought he had the solution once, two decades ago,
when he took a pile of paper-thin sheets of wood and
successfully glued them together into a cone.
Unfortunately, developing an economical manufacturing
process proved impossible.
Then, five years ago, a colleague, Satoshi Imamura,
was dining at one of his favorite restaurants. Imamura
contemplated the texture and malleability of the dried
squid he was chewing. He asked the waiter how it had
been prepared, and the waiter explained that the squid
had been soaked in sake.
Photo: Bruce Osborne
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Audiophiles: Toshikatsu Kuwahata [right] and Satoshi
Imamura developed these wood-cone speakers at
JVC in Yokohama, Japan. Larger speakers are planned.
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Imamura and Kuwahata tried soaking the speaker wood in
sake. It worked! (They also tried Suntory whiskey; it
didn't. Imamura isn't sure why, but he theorizes that
there is something unique about the acids in sake, which
is simply fermented, as opposed to those in whiskey,
which is distilled after fermentation.)
The sake makes the wood sheets malleable
but—crucially—without affecting their strength. The
sheets are then infused with resin and a mold-release
agent. The resin prevents the wood from absorbing
moisture, helping it to retain its shape in high
temperature and humidity long after it's been molded
into the shape of a speaker cone.
This year, JVC introduced its first wood-cone speaker
product based on Imamura's process, the EX-A1, an
executive desktop-entertainment system with 30-watt
wood-cone speakers. JVC expects to use the wood-cone
speaker technology in larger audio systems in the
future. The cones in this luxurious model are made of
birch, and the cabinets are solid cherry. They are
packaged with a combination amplifier, tuner, and
multiformat DVD/CD player, with both audio and video
outputs. Most important, the sound is seductive, even in
a noisy environment.
The system ships in May, at a suggested retail price
of US $550. Back in Maebashi, Japan, his mission
accomplished, Kuwahata has announced his retirement.
You Never Knew You
Needed It
TVs that light up
the room—even when they're off
Photo: Philips Electronics
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It's a classic image, the flickering light of the
TV providing the only light in a
dark room, the faces in the room
changing color as the TV screen changes.
But lighting as a byproduct of television has
always been unintentional. Until
now, anyway.
Philips Electronics NV this month began shipping
flat-screen televisions that are also room lights.
Philips's Ambilight technology projects background
light from the rear of the
television onto the wall, creating a
halo around the television, which softly lights the
room. The viewer can adjust the color choice and
brightness via remote control (whether the
television itself is on or off). Or
the system can be set to an
automatic mode, in which the lighting is
continuously adjusted in relation to
the image on the screen and to the
overall brightness of the room, determined by
built-in sensors.
The Ambilight feature is available in the Philips
Matchline 32-, 37-, and 42-inch LCD FlatTVs (priced
at US $6000, $8000, and $10 000) and
in the company's 50-inch plasma
FlatTV ($10 000).