Напольная акустика — B&W (Bowers & Wilkins) Nautilus

The Nautilus from Bowers & Wilkins is a four-way floorstanding loudspeaker built around a spiral, shell-shaped enclosure and tube loading of its drive units. It is an active design in the sense that its crossover divides the signal at line level before it reaches any power amplifier, so each speaker is driven by four separate amplifier channels rather than one.

Key specs that matter

Four aluminium-based drivers share the band. A 300 mm aluminium cone handles bass, a 100 mm aluminium and polymer sandwich cone covers the lower midrange, a 50 mm aluminium dome takes the upper midrange and a 25 mm aluminium dome works as the tweeter. The crossover points sit at 220 Hz, 880 Hz and 3.5 kHz. Bowers & Wilkins states the response as 6 dB down at 10 Hz and at 25 kHz, with nominal impedance of 8 ohm. Dispersion holds within 2 dB of the reference axis response across a 60 degree horizontal arc and a 10 degree vertical arc. Each unit measures 1210 mm high, 430 mm wide and 1105 mm deep. The speaker itself weighs 44.5 kg and its plinth another 42 kg, for 86.5 kg in total. Finishes offered were Midnight Blue, Black and Silver.

Engineering and use context

Every driver is loaded by its own tapering tube, which acts as an inverse horn and dissipates the energy radiated from the rear of the diaphragm instead of letting it reflect back inside a box. The bass tube is the long one that curls into the spiral that gives the design its name, while the smaller tubes for the midrange and tweeter point backward from the head. The enclosure is moulded from 10 mm glass-reinforced composite rather than wood. Because the division of the signal happens before amplification, an external line-level active crossover is supplied with the speakers, and no passive filter network sits between amplifier and drivers. That arrangement also lets each amplifier channel see only one driver across its own slice of the frequency band.

Pairing

A stereo pair needs eight amplifier channels in total, four per speaker. Bowers & Wilkins specifies channels rated 100 W to 300 W continuous on unclipped programme, and requires all four channels feeding one speaker to have identical gain and phase, which in practice points to four matched stereo power amplifiers or two identical four-channel models placed after the supplied crossover. Source and preamplifier connect to the crossover input rather than directly to the amplifiers.

Alternatives

The Bowers & Wilkins 801 D4 is a passive three-way tower of the 800 Series Diamond range, fitted with a diamond dome tweeter, a 150 mm Continuum cone midrange and two 250 mm Aerofoil bass units.