Bowers & Wilkins Nautilus

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Nautilus

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Briefed to stop at nothing in the quest for a perfect loudspeaker, our engineers arrived at a set of drive units whoes tapering, tubular enclosures spirited away every trace of internal resonance.

 

Design classic
Now recognised as a design classic, the original Bowers & Wilkins Nautilus is not just our flagship product, but the very pinnacle of technology innovation to which all others must aspire. It is the result of a groundbreaking, five year research and development programme to achieve, as near as possible, the perfect loudspeaker.  The Bowers & Wilkins Nautilus is recognised worldwide as an outstanding loudspeaker which continues to shape the direction fot eh audio industry to this day.  Much sought after by cognoscenti, it has been unashamedly designed with the serious audiophile in mind, not only because of its size and shape but also because of its active design – the crossover network is positioned between the pre and power amplifiers.  

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Technologies
Nautilus is Bowers & Wilkins’ technology touchstone.  The technologies developed during the five-year long research project into the perfect loudspeaker are used in almost every loudspeaker in the Bowers & Wilkins portfolio.
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Nautilus symbolises all the qualities of innovation, dedication and love of music which have inspired Bowers & Wilkins engineers, designers and production teams ever since our company was established over 40 years ago.  The Nautilus offers a uniques chance to hear music exactly as recorderd: detailed, vibrantly alive, full of power and unhindered by speaker distortion or cabinet diffraction.

Nautilus: Offers a unique chance to hear music exactly as recorded.

Nautilus symbolises all the qualities of innovation, dedication and love of music which have inspired Bowers & Wilkins engineers, designers and production teams ever since our company was established over 40 years ago.  The Nautilus offers a unique chance to hear music exactly as recorded: detailed, vibrantly alive, full of power and unhindered by speaker distortion or cabinet diffraction.  Our research teams dedicated much of their creative effort to elimination distortion in all its various forms.  The Nautilus has therefore become the first in the world to achieve near zero cabinet coloration.  

 

800TechAluminiumtweeters Aluminium tweeters
Most Bowers & Wilkins loudspeakers use aluminium dome tweeters.  The combination of lightness and rigidity they offer means that they capture the subtleties of music, such as delicate brush strokes across the surface of a cymbal with amazing accuracy.  Our latest aluminium tweeters feature a ‘crowned’ voice-coil bobbin and a silver-plated pole piece, extending the bandwidth well over an octave above the limits of human hearing, and rendering a separate ‘supertweeter’ quite unnecessary.

Aluminium tweeters: Extending sound beyond human hearing.

The delicate brush strokes across the surface of a cymbal can only be recaptured by a tweeter that’s truly linear in operation.  And that means one that uses a  dome that stays rigid and operates like a piston throughout its operating range.  Most Bowers & Wilkins speakers feature allow dome tweeters.  Our newest tweeters – as found in the 800 Series- feature a ‘crowned’ voice-coil bobbin and a silver-plated pole piece, extending the bandwidth well over an octave above the limits of human hearing, and rendering a separate ‘supertweeter’ quite unnecessary.  It is commonly believed that the best materials for speaker diaphragms, be they cones or domes, are those that exhibit high stiffness.  

ExploreTechAluminiumTweetExplode The principle is that the diaphragm then behaves as a perfect piston and does not suffer the time-smearing problems associated with diaphragm break-up.  Like many things in life, the simplistic approach has a good deal of truth, but is by no means a universal panacea.  No material has infinite stiffness and there will eventually be a frequency at which the diaphragm will cease to behave as a perfect piston.  Because very stiff materials also tend to have low internal damping, the break-up, when it occurs, can be very severe.  The resulting resonances have what is called a high Q.  The term Q has two meanings in acoustics.  It can refer to the directivity of a speaker – the higher the Q the narrower the spread of sound – and you will often see the meaning used in public address speaker specifications.  In this case, however, Q refers to the sharpness of the resonance – the higher it is, the more the resonance is highly tuned around a single frequency, putting a large peak in frequency response.  

As with a bell, a high Q resonance will ring on long after the applied signal has stopped. This is not good and the designer should make sure that the driver’s response in the region of these resonances is well attenuated by the crossover. In practice this means that the nominal cut-off frequency of the crossover filter should be set at least 1½ and preferably 2 octaves below the lowest resonance frequency. Another potential problem with stiff diaphragms concerns directivity – how much the off-axis response differs from the on-axis response. The broadness of sound dispersion depends on the ratio of the wavelength of sound to the diameter of the diaphragm. The higher the frequency, the shorter the wavelength, and the narrower the beam of sound becomes. Excessive variations in the spread of sound with frequency will lead to listeners sitting away from the central ‘hot spot’ position hearing a different sound balance and a change in the character of the various instruments. It will also impair the sound image. In severe cases, the position of an instrument may appear to change with frequency. 

 

So how does the designer avoid these problems? Making the diaphragm smaller will both raise the lowest resonance frequency and broaden the dispersion. Unfortunately, small diaphragms have to move further than large ones to produce a given level of sound and so tend to produce higher levels of harmonic and intermodulation distortion. The solution therefore is to use more drivers, so each covers a fairly narrow bandwidth and output levels can be kept high, dispersion more even and distortion low. How many drivers? To do the job properly over the full audio band really requires a minimum of four and it is no coincidence that our Nautilus™ speaker, in which all the diaphragms are aluminium, is 4-way.

ExploreTechAluminiumTweetWave For other speakers in our range, the use of aluminium is generally restricted to tweeters and bass drivers.  A stiff material is essential if one wishes to make a moving coil tweeter that extends well into the ultrasonic region.  In the bass, a stiff material is better able to withstand deformation from high pressures inside the cabinet and impulsive forces from the voice coil, thereby giving the best dynamic response.  in the midrange, when one driver is used to cover a wide bandwidth, a more flexible material with a specifically controlled break-up behaviour, such as Kevlar remains a better option.  With combined bass/midrange drivers, preference must be given to the requirements of the midrange, where the ear is at its most sensitive. 

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The sound of silence. Not all sound generated by speaker drive units is good sound. The kind that emerges from the back of a working driver, into a conventional box cabinet, can bounce around and make a mess of the good sound coming out of the front. Bowers & Wilkins’ trailblazing Nautilus™ speaker found a way around boxes. Tapering tubes filled with absorbent wadding soaked up the wayward sound energy and reduced resonances to an insignificant minimum. Nautilus Tapering Tubes are fitted to nearly all Bowers & Wilkins speakers, even when they’re not visible to the eye.

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Sound is channelled through a hollow pole magnet, away from the diaphragm, and disappears into the tail.. So all the sound you hear is good sound. When a driver is loaded by a tube of a similar diameter to the diaphragm, sound propagates down the tube as a series of simple plane waves. When the sound reaches the other end of the tube it is reflected back up the tube towards the driver. If it reaches the driver it causes delayed radiation that time-smears the original signal, blurring the clarity of the sound. If, however, you fill the tube with absorbent material and the tube is long enough, you can dissipate the energy before it reaches the end of the tube. The sound from the driver then remains clean and true to the input signal.

Tapering the tube enables you to make it shorter for the same level of absorption. It acts like a horn in reverse – reducing the sound level instead of increasing it. The limit of this type of loading is reached when the wavelength gets small enough to be comparable with the diameter of the tube. Above a certain frequency, the sound ceases to propagate as a simple plane wave and a series of cross-mode resonances are set up which can re-radiate through the driver diaphragm. To maintain the effectiveness of tube loading, you must restrict the bandwidth of each driver. This is one reason why the Nautilus loudspeaker is divided into a 4-way system. A more complex type of loading is required to cover a wider bandwidth and the sphere/tube enclosure was developed for the Nautilus 800 Series.

 

 

Nautilus Story
 

Innovation has always been the hallmark of Bowers & Wilkins.  And the five-year research project that led to Nautilus epitomises this commitment.  
 

Breaking the mould

From the stepped baffle of the DM6 to the cool modernity of the Emphasis, Bowers & Wilkins’ policy has always been to explore every avenue in the pursuit of accurate sound.  This has allowed our engineers to follow leads, which even if they ended in disappointment, added to our expertise.  At one point out energies were concentrated on dipole or backless loudspeakers, where rearward- travelling sound could radiate freely away from the drive units.  But despite a variety of inventive baffles listeners could always identify the cone materials use in the drive units.  Then came the breakthrough.  While working on prototypes for Nautilus the engineers experimented with traditional shape: the plain, tapering horn.  Only in this case, a horn which is used not to transmit sound but to absorb it.

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Art of discovery

fle of the DM6 to the cool modernity of the Emphasis, Bowers & Wilkins’ policy has always been to explore every avenue in the pursuit of accurate sound.  This has allowed our engineers to follow leads, which even if they ended in disappointment, added to our expertise.  At one point out energies were concentrated on dipole or backless loudspeakers, where rearward- travelling sound could radiate freely away from the drive units.  But despite a variety of inventive baffles listeners could always identify the cone materials use in the drive units.  Then came the breakthrough.  While working on prototypes for Nautilus the engineers experimented with traditional shape: the plain, tapering horn.  Only in this case, a horn which is used not to transmit sound but to absorb it.

 

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Learning from nature

After discovering the transmission-line principle for the top three drivers our engineers originally though a closed bo would be fine for the bass.  But listening tests showed a discontinuity between the bass and the other three drive units.  To match the sonic purity of the tweeter, the treble and the midrange driver, the bass needed a wave-guide pipe – and this created a dilemma.  The low frequency requirement dictated a non-tapering pipe 300mm in diameter and three metres long – clearly an impractical solution.  In their relentless pursuit of true sound, the research team came up with another Bowers & Wilkins’ great technical advance.  Experiments showed that a curled-up horn-shape would perform exactly as required but would occupy a much smaller volume than a straighforward pipe. 

 

Craftsmanship

Bowers & Wilkins has been manufacturing Nautilus since 1993, and the painstaking process is a perfect example of our obsessive attention to detail.

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Material perfection

 

Bowers & Wilkins’ search for the best possible quality in production means that we devote a great deal of time and care to specifying materials and components – and then to finding suitable specialists to make them. For the Nautilus™ body we engaged the services of Raceprep, a specialist company which is expert in the formulation of fibre-reinforced composites. Because of its complex shape, Raceprep engineers make the Nautilus™ shell almost entirely by hand, using a resin which has been identified by computer analysis as perfect for its purpose – ensuring maximum strength and durability. The same attention to detail has been applied to the finish for the Nautilus™ shell. Bowers & Wilkins’ paint and lacquer system is imported directly from Germany, where it is supplied only to the leading names in the luxury car industry, such as Porsche and Mercedes Benz.

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Sound work

 

Over the years, Bowers & Wilkins has built up a team of highly skilled people, who use a mix of hand-assembly techniques and semi-automatic production processes to make our drive unit components – a combination which gives us speed and flexibility when it comes to producing new prototypes or making complicated parts. It also means that we can achieve world-class levels of quality in manufacturing. For example, all Bowers & Wilkins voice coils are wet wound with high temperature resin and then baked in a special oven to ensure enhanced performance and durability. ’Wet-winding’ is a time-consuming process and some manufacturers see it as uncommercial and unnecessary. At Bowers & Wilkins, we believe it to be an essential step in achieving the kind of quality and reliability for which our loudspeakers are renowned.

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A final audition

 

Our commitment to the best means that quality procedures are built in to all stages of production of a Bowers & Wilkins loudspeaker, from individual testing of each bought-in component to rigorous checks at every stage of our own production line and a final test of every finished assembly. Every Nautilus™ loudspeaker is auditioned before it receives its final seal of approval. By the end of the process, everyone who has contributed towards making, testing and checking our loudspeakers is named on the Bowers & Wilkins quality certificate. Documents accompanying the Nautilus™ include performance plots for all four drive units, showing their near-field response and their deviation in sound pressure levels from the laboratory standard. The overall acoustic deviation for the Nautilus™ is less than half a decibel and this is corrected by the electronic crossover.

 

Price – POA

Audition by appointment only… 07 3854 0406

 

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