Premiere Design

Most speakers include drivers mounted on one or more faces of an enclosed box. But a few speaker makers take a different approach often called infinite or open baffle, in which the drivers are mounted on a flat board with no enclosure around them. One such company is Accent Speaker Technology, whose Nola brand includes the flagship Grand Reference V.

All speaker drivers radiate sound waves from their front and back surfaces. If the driver is enclosed in a box, the backwave is reflected around inside the box, interfering with the driver's vibration and thus coloring the front-radiating sound as shown in the left portion of this diagram. By contrast, an infinite-baffle design operates like a dipole radiator, allowing the backwave to go its merry way without interfering with the frontwave as shown in the right portion of the diagram. Of course, the backwave eventually hits a wall or other surface and reflects around the room, making placement of infinite-baffle speakers especially critical.

The Grand Reference V system consists of four towers altogether—two per channel—each standing seven feet tall. Each main tower weighs 300 pounds and sports no less than 19 drivers. Nine 4-inch ribbon tweeters and six 4-inch tri-laminate cone midrange drivers are mounted in an infinite baffle with their backsides exposed to the open air.

Two 8-inch magnesium-cone woofers are mounted below the tweeters and midranges and two more are mounted above, each in its own sealed chamber. Why aren't these drivers in an open baffle? According to the company, they must maintain a flat frequency response down to 40Hz, which is not possible without a baffle wide enough to avoid dipole cancellation of low frequencies—we're talking about a baffle that's five or six feet wide. And even with such a baffle, it would destroy imaging accuracy due to diffraction problems.

The separate subwoofer towers each weigh 400 pounds and house four 12-inch drivers in individual vented chambers to allow low distortion at high listening levels. Altogether, the system's frequency response extends from 12Hz to 46kHz, and it can output 120dB SPL from 20Hz to 20kHz.

That's a lot of grunt, and it ought to be for $189,000. But based on reviews of previous generations and the Baby Grand Reference ($55,000/pair) from trusted sources, I bet the Grand Reference V sounds incredible.