IMAGINE the din. Every cardboard-packed item in a supermarket could soon be
blaring out reduced-price messages or playing advertising jingles. It鈥檚 just one
of the uses being touted for a build-it-yourself, flat-pack loudspeaker
developed by British company NXT.
The Cambridge-based firm鈥檚 collapsible speakers are made of 鈥渁coustic fluted
composite鈥濃�攐therwise known as corrugated cardboard. Versions designed to
be used with home sound systems are pyramid-shaped and stand about 70
centimetres tall. Advance demonstrations for 快猫短视频 of a
拢30 pair revealed surprisingly high-quality sound that was certainly loud
enough to dance to. The sound could easily be coming from a mini hi-fi system
with normal speakers.
But why would anyone want cheap flat-pack speakers? NXT claims students might
want to carry them easily from one lodging to another, and their low cost means
children can have them in their bedrooms without parents worrying that
boisterous play will damage them. Adults can use them instead of expensive hi-fi
speakers for parties or barbecues in case drunken guests spill drink on them or
tread on them.
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Until the mid 1990s, all loudspeakers used a piston effect to pump out sound,
until NXT worked out how to generate sound by moving a flat panel. It invested
many millions in finding lightweight materials stiff enough to ensure faithful
sound reproduction. The company also worked out how to find the best place on
the panel to put the small electromagnetic exciter that converts electric
signals into acoustic waves. It now leads the field in flat-panel
loudspeakers.
Last year, NXT discovered that it could make ordinary cardboard boxes produce
reasonable sound quality鈥攇iven a decent enough exciter. So the company
designed a roughly tetrahedral box speaker
(see Graphic) that folds
flat鈥攊deal for stacking, and easy to carry, store and assemble at
home.
David S. Smith, a European company that specialises in cardboard packaging,
helped develop a tough corrugated cardboard with the correct frequency response.
The speaker is made from a single sheet of the board, pre-folded down four lines
to form a three-sided pyramid. The fourth crease allows one face to fold inwards
and collapse the structure. It can be printed with any design you want, and
topped with a weatherproof varnish.
NXT uses a flat exciter coil, 2.5 centimetres wide, powered by a neodymium
electromagnet. It sits on the inside of one face of the pyramid at its 鈥渟weet
spot鈥�. Hook the exciter up to a 15-watt amplifier and it vibrates, making the
whole pyramid flex to produce sound. 鈥淲e are already working on smaller
versions,鈥� says NXT鈥檚 Jon Vizor. 鈥淐ornflake packets will come when we have got
the right material.鈥�