Wilson Audio WATT Series 7 - Manual (Page 16)

THE WATT: A TEXTBOOK IDEAL
The following is an excerpt from Martin Colloms’ book High Performance Loudspeak-
ers , (4th Edition, pp.297-299. Pentech Press, London, 1991):
“Where price is no object, costly materials and techniques can be employed to generate
the finest results. In one system example, the WATT by Dave Wilson, the enclosure ben-
efits from many techniques to achieve a remarkably inert result. The following details are
all considered influential, including the small size (approximately 9 liters) which naturally
improves strength and also results in a small enclosure surface area with reduced acous-
tic radiation. The enclosure itself is a truncated pyramid; as a result the panels are non-
rectangular and the internal surfaces anti-parallel. The latter minimizes internal standing
wave modes while the former helps to disperse and moderate the usual plate resonances
present in conventional enclosure panels. In addition the interior is lined with anechoic
grade foam supplemented by a volume filling of polyester fiber.
The enclosure panels are cut from a dense, naturally inert composite - an acrylic, heav-
ily loaded with ceramic and a mineral powder - which may be machined like marble.
Higher frequency panel modes are controlled by a highly resistive bituminous laminate on
the inner surface while the remaining fundamental resonances are handled by heavy, 20
mm thick lead slabs bolted into position with elastic mountings to provide tuned, seismic
damping. Furthermore, the side panels are extended at the rear to form small triangu-
lar ‘wings’. A massive alloy bar is bolted up between these wings, horizontally disposed
and providing a stressed reinforcement for these largest radiating surfaces. Finally the
finished mass of approximately 25 kg provides a heavy inert foundation for the two-way
driver lineup to perform at its best. The performance attained in this enclosure design is
an object lesson in the continuing importance of enclosure coloration in box speaker de-
sign.
Both mechanical impulse tests and listening have shown that this quality of enclosure has
a dramatic effect in improving sound quality, particularly with transients, subjective dy-
namics, stereo focus and depth; as such it shows that despite considerable improvements,
we still have a long way to go in the field of commercial enclosure design. However, this
performance is achieved at high cost, approximately 15 times that of a normal enclosure
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