"Where's the tweeter?" I asked after a listen to the 97dB-sensitive Soundfield speakers, shown at Capital AudioFest in prototype form. It turned out the top drive-unit is a 12" coaxial unit, with the HF unit mounted where the dust-cap would be. "So the big-ass 18" dipole unit is the subwoofer?" No, it was explained, the18" unit in the speaker's center, behind the metal grille, is the woofer, covering the range from 50200Hz. The bottom 12" unit, mounted in a sealed enclosure is the subwoofer, handling frequencies below 50Hz. With the coaxial and 18" drivers operating as dipoles and the bottom12" unit omnidirectional, by varying the crossover between the low-frequency drivers, the speaker's radiation pattern can be made cardioid in the region where room acoustics might benefit. I had seen a cardioid subwoofer designed by Ken Kantor many years ago at a CES, and had wondered why no-one else had experimented along these lines.
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