Okay.. a little more clarification as to why I selected Wilson-Benesch (which is a relatively rare and nearly unknown speaker in the US) as having the "best" cabinet for quality, function, design and construction. Since I could not state it any better myself - I am posting information from their website. It is a little wordy but very interesting reading none-the-less.
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There are over sixteen very different and carefully selected types of material used in the enclosure alone, this is before the drivers and crossovers are introduced! Some of the materials like the spine for example require many machining operations in order to be shaped. Fourteen machining operations are required to produce one spine for one enclosure. Each Advanced Composite Technology panel is hand made and pressed in dedicated, mirror finished, stainless steel tooling. Six different types of adhesive are specified for the basic assembly. The ten millimetre thick steel plate used at the base of the cabinet to tune the low frequency port and provide mass to the system precisely where it is required is cut by laser to very fine tolerances. It can be seen that in every detail the system is quite different in every way from the many loudspeakers which have preceded it.
The name Wilson Benesch is synonymous with innovative design and advanced materials technology.
Wilson Benesch products are unique in every detail. The visual aesthetic is determined by function and engineered from the raw material under one roof. The quality of finish is a natural requirement of materials. Choice and sonic performance is everything.
ACT One derives its name from the Advanced Composite Technology panels which are used so effectively in this high performance loudspeaker. The distinctive form is both functional and attractive and incorporates the very latest technology and the very finest materials.
The ACT One is unlike any other loudspeaker. Its specification has been determined by engineering criteria which has quite naturally brought about a three dimensional form which is pleasing to view from any angle.
The carbon fibres that form the large curved side panels compliment the wood grain. Engineering components like the ten millmetre thick steel plate at the base of the cabinet are carefully considered in how they function aesthetically and other aspects of the design have been re-evaluated and addressed in order to achieve optimum performance both sonically and visually.
Externally the structural needs of the cabinet function without getting in the way of the pressure waves created by the powerful drivers. The low diffraction of the form allows the speaker to virtually disappear as the ear cannot detect the diffraction patterns commonly detected with less well considered speaker enclosures. Internally the curved forms prevent the manifestation of standing waves. The small amount of precisely located damping material mops up any unwanted third harmonic and is used in such small quantities that its effect on the drivers is virtually inaudible.
Curved forms have always been used in both natural and man made structures and are an important design parameter in terms of the effective strength of materials. In 1975 D.A. Barrow presented a paper to the Audio Engineering Society entitled "Sound output from loudspeaker cabinet walls". His investigations indicated that structures with curved surfaces were extremely rigid in terms of both expansion and compression waves, offering the potential of very low colouration structures. Although A.C.T. panels are extremely expensive they offer unique and very significant advantages over all other materials used to date. Some of these advantages are outlined below.
1. Low mass structures, as in the Wilson Benesch turntable sub-chassis, are incapable of significant energy storage. Avoiding this problem is essential to un-coloured reproduction. With high performance drivers massive transients can inject a lot of energy into an enclosure structure. Only by minimising this absorption can subsequent re-emission be minimised, this is quite different to suppression which is rather like closing the stable door after the horse has bolted.
2. A.C.T. panels of a given thickness are over five times stiffer than a similar M.D.F. board. In practice this means that the first resonant frequency of the A.C.T. panel when installed in the cabinet is well into the treble range where energy levels are significantly lower than in the bass regions. Emissions from the enclosure walls are subsequently in the ultrasonic range. (With reference to the finite element analysis diagrams it can be seen that the first resonant frequency of the A.C.T. panel is five times higher than that of a similar M.D.F. board Curvature of the panel would give a further 5 fold increase in resonant frequency).
3. The chamber created by the curve avoids the standing waves that are inevitable in box designs. Standing waves accentuate particular frequencies and distort the quality of the signal by producing an inaccurate output.
4. Nearly thirty years ago a paper by H.F. Olsen appeared in the Audio Engineering Society entitled "Direct radiator loudspeaker enclosures". Twelve different shapes of cabinet were tested for their effects on the final frequency response of a loudspeaker. Essentially the sphere provides the smoothest characteristic whilst the box provides worst. The A.C.T. Two Loudspeaker exhibits very low diffraction surfaces on both the exterior and interior forms. They provide for a broad dispersion of the signal avoiding the forward beaming effect of a large box shaped baffle designs. The atmosphere and sound stage of recordings are reproduced more faithfully as a result.
5. A curved chamber coupled with sloping braces reduces the need for absorbents enabling the drivers to breathe effortlessly and without the colourations that are commonly introduced by large quantities of absorbent.
6. A.C.T. panels are a matrix composed of literally thousands of anechoic chambers, the panels actively deal with resonant energy in a way that no other panel to date can. The materials used in its construction have intrinsic self-damping characteristics. No additional damping materials are required that will be prejudicial to the quality of the sound reproduction. If you touch the panels when they are playing loud you will appreciate just how effective they are.
