Don Keele & the Constant-Directivity CRT36 Speaker
Speaker engineer Don Keele almost wrote the book on measuring speakers. so when I bumped into him at RMAF and he told me he had a new speaker on show, I went straight to his room. There, I saw and heard the CBT36, which as you can see, is very unusual in both appearance and design. CBT stands for Constant Beamwidth Transducer
and is based on unclassified military underwater sound beam-forming research. There are 72 0.75" tweeters crossed over to 18 3.5" Dayton Audio midrange units, arranged in groups that, with the 36° arc of the 5'-tall array, gives sound that doesn't change its balance as the listener sits or stands. And as you can see from the mirror that Don has slipped in front of the speaker in my photo, the ground-plane reflection of the array effectively doubles its height.
The CBT36 is available now from Parts Express as a kit for a very reasonable $1980/pair or as fully finished speakers in the future from Audio Artistry for $8500/pair. Demmed with Jeff Rowland Design Group amplification and crossed over to an active woofer below 60Hz with a DEQX DSP unit, these speakers produced one of my best sounds at the 2011 RMAF.