B&W Nautilus 805 loudspeaker Page 2

Sitting just below the mid/bass driver, and almost as large, is the double-flared—one internal flare, one external—reflex port. This has a 2" outlet, twice the diameter of the 805 Matrix's vent. Its surface is dotted with molded "golf ball" dimples to smooth air flow and avoid the chuffing sounds sometimes generated by reflex designs. While the Nautilus 805 does not use the Nautilus 801's 1.5"-thick, 24-lamina birch cabinet, its curved-profile, 0.75"-thick MDF walls add stiffness to reduce cabinet resonances and to break up internal standing waves. Inside, its interlocking cells prevent the cabinet walls from flexing. My ruler measured the Nautilus 805 to be 3.6" taller, 4.6" deeper, 4.2" narrower, and 1.3 lbs heavier, with 3.5 liters more internal volume than its predecessor.

The Nautilus 805's drivers are derived directly from the Nautilus 801's. the Nautilus 805 has a lower 120W system power rating. Its 1" aluminum-alloy dome tweeter has a neodymium/iron/boron magnet structure with copper-clad aluminum wire wound on a Kapton former, and is ferrofluid-cooled to improve power handling and reduce compression related to overheating. The tweeter housing is set behind the baffle to time-align the system, and uses a Raychem "Isopath" decoupling material to reduce vibration.

The 6.5" mid/bass cone uses the woven-Kevlar construction of the Nautilus 801's midrange driver. In the 801, this cone does best without a rubber surround, as it reproduces music only between 400Hz and 3kHz, thus requiring minimal excursion. In the 805, however, the driver must move much more air to extend its response down to 40Hz, so a rubber-based surround is very much needed. Its 30mm voice-coil is wound on a Kapton former, all built onto a solid die-cast frame.

As in the rest of the Nautilus line, the crossover is mounted on the 805's aluminum baseplate. This serves as a heatsink for the noninductive thick-film resistors. Components have been optimized by careful selection of polypropylene film capacitors and hefty air-cored inductors. Although the Matrix 805's crossover had similar filter slopes, its -3dB down point was extended to 42Hz by an outboard electronic equalizer not available for the Nautilus 805.

Two pairs of heavy-duty, plastic-shrouded German WBT speaker terminals—one pair each for the tweeter and mid/bass drive-units—include slots for spade lugs and a hole for single banana plugs. These various slots and holes in the plastic shroud were a perfect size to accept the spade lugs and single banana plug terminations on my biwired PSC speaker cables.

My review samples were finished in lustrous cherrywood. Accompanying them were instruction manuals in 13 languages. As a reviewer, I also received brochures detailing the development of the Nautilus technology, a training DVD on Nautilus design in three languages, and accessory packs with two terminal link cables, four self-adhesive rubber pads, and a microfiber cleaning cloth. Best of all, B&W sent along a pair of snazzy art-deco aluminum FS-N805 stands that attach—via large Phillips-head screws—to the 805's bottom plate for the most secure and vibration-free mounting I've yet encountered in a two-way bookshelf design. Overall, the superb build quality, engineering, and fit'n'finish of the Nautilus 805 raise the bar for all minimonitor loudspeakers.

Setup
Testing began by exposing the Nautilus 805s to 15 hours of the "Special Burn-in Noise Track" on Stereophile's Test CD 3 (STPH006-2 / order online). Then the 805s were subjected to nearfield (8') and farfield (16') comparisons, low-frequency signal-generator sweeps, phase checks, pink-noise tests, and optimization of listening chair for optimal soundstage and imaging. The Nautilus 805's reflex-tuned design shut off cleanly in my room below 40Hz with no audible doubling. Pink-noise checks showed no change in tonal balance when I shifted laterally, but a definite suckout in tonality when I stood up during the "sit down, stand up, walk around" listening test. This problem was not evident when I sat and listened to the Nautilus 805s on their FS-N805 stands. These set the tweeters 39" above the floor, about 2" above my seated ear height. Under these conditions, I heard tightly focused, three-dimensional imaging.

For all listening sessions, the Nautilus 805s were placed in my preferred speaker locations: 62" from the rear wall of my room (footnote 1), 45" from the side walls, and 84" apart, the speakers sitting on a circular area rug. Stereophile's Test CD 2 (STPH004-2) was used for channel identification and phasing, and the pink-noise tracks on the first Test CD (STPH002-2) were used to adjust the speaker positions until I could hear the in-phase pink-noise signal as a small, well-defined area of noise focused dead center. Imaging and soundstaging were optimized when the speakers and listening seat described an 81" equilateral triangle, as measured from the tweeter centers.



Footnote 1: My listening room measures 26' L by 13' W by 12' H (5500 cubic feet), with a semi-cathedral ceiling; it opens into a 25' by 15' kitchen through an 8' by 4' doorway.
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