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The Solution was Sake

Strange ingredients make a better loudspeaker

3 min read

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


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.

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


Toshikatsu Kuwahata [right] and Satoshi Imamura developed these wood-cone speakers at JVC in Yokohama, Japan. Larger speakers are planned.

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

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).

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