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THX Speaker System Yields Multiple Stereo Sweet Spots

Las Vegas – THX Ltd. plans at to
demonstrate during International CES a horizontal single-enclosure speaker that
“puts the stereo sweet spot in every chair in the room,” the company told

The THX Steerable Line Array
technology, which the company could decide to license, uses digital signal
processing (DSP) and other techniques to create “multiple unique sweet spots at
the same time so everyone can enjoy content at the same time no matter where
they are sitting in the room,” the spokesperson explained.

The technology will be demonstrated
in a concept product at the company’s private suite at the Renaissance Hotel.

The concept system that THX will
demo delivers left and right channels from 92 tiny drivers in a line array in
an enclosure with only about a cubic foot of internal volume. DSP is applied to
direct multiple beams of sound to any part of the room, enabling every seat in
the room to become “the best seat in the house,” the company said.

The technology is not dependent on
reflecting sound waves off walls, added THX senior VP Laurie Fincham.

The concept speaker is 10 inches
high by 82 inches wide by 4 inches deep and features an outboard amplifier/DSP
module that, if it were embedded inside the enclosure, would add only about an
eighth of an inch to the enclosure’s depth, said Fincham. Frequency response is
30Hz-20kHz with sound pressure levels of “well over 100dB,” he said.

The concept speaker will steer sound
to create eight sweet spots in the room, but if higher processing power were
used, the technology could create more simultaneous sweet spots, Fincham noted.

Because of its scalability, the
technology can be used to create smaller or larger enclosures with as few as 25
drivers or as many as 100 depending on the desired sound levels and low-frequency
cut-off, he said. “This could be as little as one liter of total volume or
equivalent to a 4-inch cube. The bottom line is that the enclosure is small and
takes up considerably less space than existing systems.”

A Steerable Line Array stereo system
“can be made so unobtrusive that it can disappear leaving only the music,” a
company statement added. The system’s low-profile analog amplifier delivers
“traditional audiophile quality” with “modern requirements for the highest
energy efficiency.”

The technology could be designed
into two vertically oriented towers in lieu of one horizontal speaker to
deliver the same effects, said Fincham. The technology could also be used in
two horizontal speakers, one for the front of the room and one for the back, to
deliver multichannel surround sound to multiple sweet spots in a room, he

In the demo speaker, tweeters are positioned
on the front panel and fire forward. Low-frequency drivers are mounted inside
the enclosure at a 90-degree angle to the tweeters, firing into a front-panel
slot running up and down the face of the enclosure. Each driver is powered by
its own analog amplifier.

The technology is based on general
principles outlined in an Audio Engineering Society paper published by Fincham
and Peter Brown of THX. “With steering there are two aspects that technologies
need to address,” Fincham added. “One is the steering of sound to one or more
listening locations, and two is controlling beam width. Our system handles both
these aspects at the same time. We can ‘illuminate’ many listening locations,
and we can control beam direction.”

In 2008, a U.K.-based company called


technology that promised a room-wide sweet spot delivered by a single-enclosure
speaker. Other companies use DSP in speakers to steer the stereo sweet spot to
a particular location to compensate for poor speaker placement but not to
deliver a sweet spot to every seat in the house. Other companies, such as
technology developer


use DSP to steer a surround-sound sweet spot to a specific location in a room.