JVC Engineers Developed Wood Speaker Cones, with a Little Help from Sake (Rice Wine)

I found this article in the April 2004 issue of IEEC Spectrum. It is also available on line:
http://www.spectrum.ieee.org/WEBONLY/resource/apr04/0404tool.html

The Solution Was Sake

Strange ingredients make a better loudspeaker

By Tekla S. Perry

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.

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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.

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AUDIOPHILES: Toshikatsu Kuwahata

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.​

 

I think they'd have been better off drinking the Sake.

 

Would be interesting to hear 'em...gotta say, they're probably prettier than good sounding.

 

This is very poetic in a Japanese sort of way... could be an April Fool joke, though

 

If I get one of those, can I say "I got wood"?

 

If one of the speakers go would you say "I've blown a woodie?"

 

Don't blow them, Jamie, just keep 'em throbbing....

 

For heaven's sake (pun intended), this has to be an April fool joke. Even the best equipment feet like Harmonix don't use sake, and it works nevertheless...

 

An April fool joke? The IEEE Spectrum is a monthly magazine that would never devote a whole month worth to a joke! And check out on JVC's web site this page introducing the EX-A1. Since when does April fool become a month-long thing?

http://www.jvc.co.jp/audio_w/product/system/ex-a1/index.html

 

I would guess that speakers made from wood would have significant limitations on how big a cone you can have. Self damping properties may be decent, but low mass they're not. I don't think it's totally marketing that has them debuting in a "desktop" system.

John K.

 

Interesting...

 

I agree that it will be easier to make smaller cones. The IEEE article does mention "JVC expects to use the wood-cone speaker technology in larger audio systems in the future".

 

I would like to also but historically there is apparently a prejudice against Japan-made/designed speakers in the hi-fi community. Can't say it's baseless.

 

Vifa (Denmark) manufactures a wood pulp based woofer. Interesting design!

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=297-370

Seems to me that wood pulp or fiber would be a relatively inert speaker cone material.

 

I'm going out on a limb to say that sake-soaked wood sheets should be better than wood pulp.

 

Sake is more "rice beer" than "rice wine". Most people call it rice wine - but look how it is made; calling it beer more closely describes the fermentation process sake goes through.

 

You could be right. One should never underestimate the Japanese, especially as they have a tradition going back hundreds of years, of master-craftsmanship in materials and design.

Take the beauty, simplicity and efficiency of the traditional Japanese sword - a craft perfected over many years through a system of master/student tuition. The great Koetsu cartridges come from a designer and craftsman whose family lineage goes back through many generations of swordmakers.

So, could they do something special with a wooden drive-cone? I don't know. There's more to loudspeaker design than physics. In fact, these days, when much of the physics is made trivial by inexpensive, readily available PC programs, the real art starts where the physics ends.

Even so, in order to sound better than a modern aluminium cone (for example) the wood (plus its resin) would have to be very thin to have a comparable mass. A cone must have good acceleration and that means light weight. Then it's a question of the frequency at which 'cone break-up' occurs and the character of that break-up. 'Cone break-up' is a very negative sounding term but in fact it can be a good thing and perhaps it could be better described as 'high frequency cone flow'. If this occurs in a 'musical' way, it can have advantages over a rigid cone with its subsequent dispersion patterns.

They do make one or two interesting statements on their web site about sound propogation and damping in wood.

If I had to guess I'd say that the driver would have a very pleasant and musical timbre but is unlikely to be the last word when it comes to speed or detail.

Who knows? I could be way out here. I'd like to listen to them in my own system.

 

Fostex makes some cones with different fibers--banana and kenaf. This is partly for environmental reasons as well as performance. Mention here at Madisound: http://www.madisound.com/fostex.pdf.

John K.

 

Call it whatever we want...I still can't stand the stuff. Definitely must be an acquired taste. Tried it only once or twice in my life. I mean, actually drinking it, not using it for other purposes.

Hmmm...I wonder if I should design the world's first vermouth-cooled tweeter to go with sake-soaked woofers?

 

And one would think that solid wood speaker housings would sound better than mdf...

 

And then again, maybe it only sounds good if the listener has soaked himself with sake...as in drinking several glasses of it.

 

Not sure--they're both technically "wood" products, although MDF would be stronger in some cases. However, I'd expect wood or MDF to sound better than a plastic housing.

 

Let drink (sake) to that!