British lead the way in hi-fi revolution

YOU can hang them on your wall, paint them, wallpaper over them, make them as small as a credit card or as big as a ceiling tile, mount them underwater or in cars. What else but flat loudspeakers - unveiled yesterday by a British company which aims to revolutionise home hi-fi from this summer. The technology used to make the revolutionary speakers, which are less than two centimetres thick, emerged in 1993 from a British military project to soundproof helicopter gearboxes.

What the team discovered was that flat speakers which would give authentic audio reproduction were feasible. You simply had to solve a fourth-order differential equation including eight or so variables, including the size and material properties of the speaker.

"The principle is like a piano soundboard," explained Stan Curtis, chairman of the loudspeaker company Wharfedale yesterday. "A lone piano string doesn't make much noise. But the soundboard resonates, so you can hear one piano throughout the Albert Hall. Conventional loudspeakers are like violins - you need more of them to make more noise."

The flat Wharfedale NXT speakers will cost about pounds 200 from retailers like Dixons and Curry's. They will not suit the top-end audiophile - for whom the joys of positioning speakers and producing a room where an imaginary orchestra's members can be pinpointed are essential. But The Independent's (fairly unscientific) listening test suggested that the new speakers could quickly replace the wooden boxes that have cluttered living room floors and bookcases ever since hi-fi meant having more than a Dansette and a stack of records skewered above it. "True, it won't satisfy every hi-fi buff," said Mr Curtis. "But this is only the first generation. These are aimed at the average enthusiast. It doesn't give you that pin-point sound, but it offers a great "surround" sound, which is especially good for home cinema."

Other obvious applications include announcement systems and loudspeakers for computers - both of which Wharfedale is already demonstrating.

The first prototypes, produced with the Defence Research Agency (DERA) in Farnborough, used materials such as carbon fibre and aircraft-quality aluminium which meant they cost about pounds 800 each. But on discovering the soundboard principle, the team cut the costs so that parts for the new speakers cost just pounds 5 each.

Wharfedale has licensed the technology from NXT, the company set up to develop the DERA discovery. Essentially, each speaker consists of a transducer which excites resonance in the air cells of a honeycomb matrix between the panels.

Mr Curtis said: "People are always criticising us in Britain for having great ideas but not getting them into production. Well, here's one which we have."