20,000 Hertz Under the Sea

B&W's Nautilus speakers are not new—they were introduced in 1993—but they remain unequaled in the sheer beauty of their design. And that design isn't merely for the sake of visual impact—it's a classic case of form following function.

Starting with the proverbial "blank sheet of paper," company founder John Bowers initiated a research project to create a speaker with none of the coloration associated with conventional designs. After Bowers' untimely death in 1987, Laurence Dickie took up the challenge and brought Nautilus to fruition.

Dickie knew that the internal resonance of any cabinet is the primary source of acoustic coloration, so he decided to use a separate exponentially curved transmission line or "lossy waveguide" behind each driver, which minimizes coloration from the backwave. There are no corners or edges that would introduce unpredictable resonances, and the waveguide is designed to limit the reproduced frequency range of each driver to the desired values. The 12-inch woofer's transmission line is curled up like a snail shell or, more aptly, an ammonite nautilus, while the waveguides of the other three drivers extend straight back, forming three graceful "antennae."

The four drivers themselves are purpose-built for the Nautilus, each behaving as a near-perfect piston within its operating range. That range includes a 2-octave "guard band" between the upper limit of reproduction and the first break-up mode. All four drivers are decoupled from the cabinet with O-rings, and the woofer is further supported by a load-bearing suspension at the rear of its magnet.

The woofer consists of a one-piece aluminum cone whose frequency response extends beyond 1.5kHz, far above its operating range, with a 21-pound magnet and 4-inch voice coil. Two midrange drivers include a 4-inch, flat-front driver that delivers the critical two octaves from 220 to 880Hz and a 2-inch aluminum-dome midrange for the next two octaves. A 1-inch aluminum-dome tweeter delivers the remaining three octaves.

Just as important as the drivers and transmission lines are the active crossover filters—in this case, housed in an outboard unit with balanced and unbalanced I/O. The non-resonant electronics are designed to deliver a flat time and phase response, eliminating off-axis lobes common to passive crossovers. This also eradicates any interactions between the speaker and amplifier, but it does require a discrete, matching amp channel for each driver—at least 100 watts per driver with 500 watts recommended for the woofer.

The final result is an astonishing frequency response of 10Hz-25kHz (top and bottom down by 6dB), while the response that deviates from flat by no more than ±0.5dB is said to be 25Hz-20kHz. Such sonic depth can be yours for $64,000/pair or $160,000 for a 5-channel system—no need for a subwoofer, though I would prefer to use one even with these speakers because subs are ideally placed in different locations than the mains. Of course, the Nautilus doesn't exactly disappear into the decor but rather suggests that the decor be designed around it—I'm thinking portholes and fish tanks.

I've never heard the Nautilus system, but I've listened to plenty of other B&W models, and I can honestly say they are among the best-sounding speakers in my experience. I have no doubt that the Nautilus sounds as beautiful as it looks, which would make Captain Nemo proud.

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