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Two Upscale Brands Add Wireless Subs

CEDIA Expo 2009 Atlanta – Two high-end
speaker brands – KEF and Martin Logan – are coming to the Expo with their first
wireless subwoofers.

At an offsite venue, KEF
plans to unveil its first wireless subwoofer, the $1,200-suggested HTB2SE-W,
which integrates wireless technology previously available in a kit for adding
wireless to surround speakers.

KEF’s wireless solution features a 1.1Mbps data rate to allow for
uncompressed PCM transmission, which typically extends up to 80 feet. The
company uses advanced error protection and “pre-emptive” adaptive frequency
hopping in the 2.4GHz band to hop to the best available channel before errors
occur, the company said.

The sub enclosure is round to eliminate internal standing waves,
and it can be set up horizontally or vertically. It features 250-watt Class D
amp, 10-inch driver, passive radiator and embedded wireless receiver. It is
packaged with a transmitter and ships this month.

MartinLogan will
launch its first wireless subwoofers, the $695 12-inch Dynamo 700 rated at 300
watts and $995 10-inch Dynamo 1000 rated at 500 watts. Both require the use of
a separately sold $119-suggested SWT-1 wireless transmitter. They ship in

The sealed-box subwoofers can be configured for down-firing or
front-firing orientation for placement in cabinets or on floors, respectively,
without using any tools. A grille cover and 90-degree RCA adapters are provided
for front-firing placement.

They use Class AB
amp circuitry combined with variable audio tracking power supplies to improve
efficiency over traditional Class
AB amplifiers while operating at
lower distortion and noise than high-efficiency Class D amps, the company said.
They feature IME (inverse mathematical equalization) filter to deliver
low-frequency response that’s more accurate than what can be delivered by a second-order
high-Q filter, the company said. The low-pass filer features variable 35-120Hz
cutoff points. An LFE input bypasses the internal filter for use with A/V
receivers or preamp processors with their own low-pass filters.

The company chose a sealed-box design to exhibit less
transient-blurring group delay while delivering smooth response, the company