Sonus Faber Guarneri Evolution loudspeaker
At present, my writing chores are divided between two fields: domestic audio and lutherie. Having invested considerable time in both, and having by now met a number of builders who are distinguished in one or the other, I can say with all confidence that the best share a simple, single point of view: Everything makes a difference.
There are dissenters, of course. In audio, some scoff at the notion of audible differences between, say, aluminum and steel amplifier cases, or between shellac and polymer coatings for transformer windings. In lutherie, the skeptics would have us know that a guitar with a mortise-and-tenon neck joint can sound just as good as one with a dovetail joint, and that the production advantages of catalyzed finishes on mandolin bodies far outweigh any "imagined" performance disadvantage.
Yet in both fields there are many quiet souls who quietly know better. In domestic audio, their number would seem to include Sonus Faber: an Italian loudspeaker manufacturer whose success has one foot in the world of lutherie, and whose efforts leave no stave unchiseled in a quest to make music sound more than just "silver-gray / Placid and perfect," as poet Robert Browning has the Renaissance painter Andrea del Sarto say.
The reference is more apt than I intended: The first Sonus Faber Guarneri loudspeaker was made on commission in 1993, for the Salon of the Violin in Cremona, Italy, where it remains on permanent active display, surrounded by the stringed instruments produced during that city's golden age. That model's full name was Guarneri Homage, for the obvious reason. After that came the Guarneri Memento: slightly different finish, considerably different driversand a bit room-fussy, or so I'm told.
That brings us to the third and most recent iteration of something that was not, at first, intended to be a commercial product: the Sonus Faber Guarneri Evolution.
Outwardly, the Guarneri Evolution is a compact, two-way, stand-mounted speaker, albeit one whose earnest appearance suggests something more beneath the skin. Indeed, the Guarneri's enclosure isn't so much a cabinet as it is a combination of complex structures. A spare wooden frame incorporating a single lateral brace is fastened to a pair of sides that are formed in the manner of most archtop guitars (footnote 1): laminated from several thin sheets of tonewood and shaped into a graceful curve on a custom-made press. Those elements are clamped together with upper and lower plates machined from a proprietary aluminum alloy called Avional, then fastened to an Avional rear structure, the edges of which extend into a pair of sound-shaping fins.
As in lutherie, orientation of the grain in the Guarneri's wooden parts is taken into account during assembly. Similarly, construction techniques are chosen that controlrather than squelch altogetherresonant energy within various parts of the enclosure: A tuned mass-damper system comprising a short, thick truss rod and a concentric pair of metal discs is fastened to the top plate and adjusted to a precise (and not at all excessive) degree of tightness, while constrained-mode damping sheets with flexible alloy skins are applied to the inner sides, along with thick slabs of a woolly, felt-like material. Thinner pieces of the latter are also used to line a reflex port that's built into the Avional rear panel, while another type of damping sheet occludes the throat of the port, and yet another type of batting fills the area below. Finally, the entire upper half of the enclosure is stuffed with a sort of damping "pillow"a 20"-wide black fabric bag filled with Bubble-Pak.
The baffle is made of 1"-thick MDF, precisely machined to incorporate chamfers on the outside and some strategic bracing on the inside. Every outward surface of the baffle is covered with a thin layer of supple black leathereven the facings for the driver flanges. I'm told the leather serves two purposes: blunting the bounce of stray high frequencies, and providing just the right, pliant gripa single organic lock-washer, if you willfor the Torx-head woodscrews that hold the drivers in place. Having removed and replaced one of the low-frequency drivers myself, I can attest to the latter function.
The Guarneri Evolution's two drivers are designed by Sonus Faber and custom-made for them. The low-frequency driver is a 7" ScanSpeak unit with a very soft rubber surround and a black cone of pulp resembling papier-mâché. (Sonus Faber describes the cone material as "real-time air-dried and non-pressed cellulose fiber." Italy's hyphen shortage is now explained.) The driver has a machined center hub (I can't quite call it a phase plug, since it doesn't protrude far enough into the apex of the cone to hinder the propagation of any waveforms), a very robust magnet, and a cast-alloy frame. The high-frequency driver, also beautifully made, is a 1" silk-dome tweeter designed by Sonus Faber cofounder Ragnar Lian for ScanSpeak. It incorporates a loading chamber of its own, made of plastic.
The hardwired crossover network sits at the bottom of the enclosure, apparently in direct contact with the lowermost Avional plate (though there also appears to be a plywood or MDF structure of some sort down there). Among the crossover elements are five very large Mundorf M-Cap capacitors and four hefty Jensen chokes, the latter obscured with a rubbery covering. In all, the crossover network takes up a good deal of real estate inside the cabinet. Stranded wires with clear-plastic insulation are used for connections where axial leads can't reach, and the two pairs of loudspeaker connectorsalso fastened to the Avional rear panelcan be used for biwiring or even biamping, if so desired. The crossover frequency is stated as 2800Hz, and the computer-designed network is described as comprising composite slopes.
Back to the skin: The shape of the speakers in the Guarneri line has been likened by pamphlet and press alike to that of a lute. I don't quite see the resemblance, unless the shape one has in mind is the enclosure's cross-section, viewed from above: itself something of a stretch. But I won't quibble with the sheer beauty of the Guarneri Evolution's bent wooden sides, or with that shape's effectiveness in preventing the propagation of internal standing waves. The rich laminate of okoume, an African wood superficially similar in appearance to mahogany and commonly used in marine-quality plies, is inlaid with thin strips of ebony, then coated with multiple hand-rubbed layers of nitrocellulose lacquer (just like a you-know-what-al instrument), while the Avional pieces are all plated in rich, glossy nickel. These are damn nice-looking speakers.
There's more to the Guarneri Evolution than fits in its enclosure per se: The 31"-tall Evolution stand would seem to contribute generously to this loudspeaker's performance. (The two elements are nevertheless priced separately$20,000 for the speakers, $2000 for the standsto accommodate shoppers who insist on skipping the stands.) Key to the Evolution stand's performance is an internal lever-and-weight systemanother tuned mass damperthat's used to counteract structural vibrations. Think of this as a pendulum complementing and stabilizing the inverted pendulum of a heavy speaker atop a comparatively flexible stand, much as we find in the best tall buildings.
Footnote 1: By contrast, the sides of most flat-top guitars, like the sides of most violins, mandolins, and lutes, are formed from single, solid pieces of wood, not laminates.