6
Exponential line loading is used for all four
drive units, primarily to achieve freedom from
resonance and reflection, but also for the
damping effect on the fundamental resonance
in the low frequencies.
The two dome units are tightly coupled to
their respective wave guides via a hollow pole
magnet which causes minimal discontinuity to
the advancing wave front.
A hollow pole magnet is also to be found
behind the lower mid diaphragm supported by
a chassis which itself forms the first 50mm of
the wave guide. The tube to which this is
attached is shaped to smooth the transition
from the chassis.
The distinctive natural appearance of Nautilus
is derived from the best compromise of folding
a tapered tube to save space whilst maintaining
the highest curvature-to-width ratio. Traditionally,
folded pipes have involved many 180° bends
which have serious frequency dependent
transmission properties.
Enclosure
10mm thick Glass Reinforced Plastic (GRP) has
been used for the exterior surface which, when
coupled with the doubly curved shape, results
in an extremely stiff enclosure. The inner turns
of the spiral are bounded by a foam filled GRP
which braces the opposite faces of the snail in
a manner similar to the Matrix type enclosure
perfected by Bowers & Wilkins.
The external form of the Nautilus has been
achieved using a blend of hand-built forming
and advanced CAD technology borrowed from
the automotive industry. This enables Bowers &
Wilkins to maintain mathematical accuracy of the
wave guide and to produce the final mould tool
to submillimetric accuracy.
The high gloss surface finish is the result
of using a two-part acrylic paint with a deep
lacquer coat for lustre and durability. A 50kg
block of polished terrazzo type material supports
the complete mollusc.
Summary of Contents for Prestige Nautilus
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