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BOSTON AUDIO SOCIETY
January 2010 Meeting
Date: Thursday, January
14, 2010
CORRECTED TIME: REFRESHMENTS 7PM, MEETING 7:30 PM
Place: The Walsh Function Room @ Boston College
Featured Guest: Don Keele
Topic: The Boston Audio Society, Boston Sections of the Audio Engineering
Society,
and the Acoustic Society of America Presents: Introduction to CBT Loudspeaker
Arrays
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DON
KEELE |
Don Keele will talk about his line arrays based on CBT
technology. He has been an ardent advocate and evangelist for the concepts
for over ten years and believes the CBT knowhow can vastly improve the sound
field uniformity of existing line arrays and conventional loudspeaker systems.
Don will discuss the background and history of CBT arrays and will describe
and discuss the measurement and simulation
results of several CBT line array prototypes that were constructed for home
applications.
CBT, which stands for "Constant Beamwidth Transducer',
is a term originated by the U.S. military in a series of three un-classified
Naval Research Lab ASA papers published in the late 70s and early 80s. These
papers describe spherical-cap underwater transducers with special frequency-independent
"Legendre" shading that provide extremely-uniform broadband coverage
without the need for any special or complex signal processing.
The CBT loudspeaker arrays provide directional performance
and sound-field coverage that borders on revolutionary. The CBT arrays provide
a broadband 3D sound field that is incredibly uniform and well behaved with
frequency at all distances from very close to far away. The vertical bandwidth
control and coverage of the CBT line arrays often exceeds the finest constant-directivity
pro horns.
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| DEMONSTRATING
THE CBT LINE ARRAY |
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The CBT line arrays provide a very-tight extremely well-controlled
vertical sound-field coupled with a well-controlled very-broad horizontal
coverage. CBT array possibilities extend over the full loudspeaker product
range from professional, commercial, consumer, home theater, computer, and
multimedia
For the first time, these arrays provide the capability
to implement a true broad-band constant-bandwidth/directivity/coverage systems
in a home or pro environment. The so-called "ground-plane" CBT
arrays are specifically designed to operate near a reflective surface such
as the floor or ceiling, and to not suffer from destructive floor-bounce
reflections.
Don Keele has worked for several companies in the area
of loudspeaker R&D and measurement technology including Electro-Voice,
Klipsch, JBL, Crown, and Harman. He holds three patents on "constant-directivity"
loudspeaker horns, has four patents pending, and is a fellow of AES and
a member of ASA.
Mr. Keele received the TEF Richard C. Heyser Award in
2001. In 2002, he received a Scientific and Engineering Academy Award from
the Academy of Motion Picture Arts and Sciences for work he did on cinema
constant-directivity loudspeakers.
Guests are always welcome at BAS meetings.
* Note that the event is on a Thursday*
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