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unclejed613 26th February 2007 03:09 AM

has anybody ever seen a "surface driver"?
i saw one of these devices back in the '70's. it consisted of a woofer magnet with a steel plate attached to it rather than a cone. it could be mounted on a surface, such as a floor, that would become a sounding board. the particular one i saw was rated at 250 or 300w. i have been looking for something similar for an idea i have, but the compny that made the one i saw has vanished...... IIRC the name of the company was Planar Sound out of North Carolina and the device was called a Sound Plate.

the company i work for has a speaker reconing shop, and i'm thinking of describing the sound plate to the reconing tech to see if we can make one. if the thing was patented, the patent could be expired by now.......

unclejed613 26th February 2007 04:17 AM

i found something similar in patent 4514599 with a piston driven by a voice coil, and the piston attaches to a car body to transmit sound.

mightydub 26th February 2007 04:24 AM

you mean like these:

or these:


Renron 27th February 2007 12:47 AM

I worked on a high end home once that had hockey puck transducers on the inside of the sheerock walls, they made the entire sheetrock a "cone" abiet as flat one. They did not have any highs and the mid was not very clear though.

Paul Burton 27th February 2007 09:26 AM

Direct excitation of surfaces

Check this out:

There have been "knockers" or "shakers" around for many years. The above is a magnetostictrive variant. It's not hi-fi, but it certainly works.

There is also a system called "Whispering windows" that caused a minor stir in London in 2003 when it was installed in a shop window display in the flagship John Lewis store in Oxford Street:

It later showed up in a bank window in Cambridge, and probably elsewhere as well, but that is where I encountered it. Although quiet, it did work, although it seemed not to attract much attention - maybe the naff advertising being "broadcast" on a flat screen TV on the other side of the window wasn't compelling enough...


ThomasW 25th March 2007 05:56 PM

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