Stand Loudspeaker Reviews

As founder and chief designer of Sonus Faber, Franco Serblin designed and manufactured many loudspeakers of acclaimed high quality, mainly in box form. Nevertheless, he remained painfully aware that such conventional rectangular parallelepiped constructions inevitably possessed an inherent and hard-to-suppress resonant signature characteristic of box-form cabinetry, significantly differing from that for a musical instrument. Franco had long obsessed over the sound and construction of classical string instruments, violins, violas, and cellos made by grand masters over centuries. He valued highly those richly resonant, expressive, complex sonic signatures.

Most loudspeakers have, to some degree, a characteristic voice or color, partly stemming from their materials and construction. While designers have become skilled in controlling those voices, especially working to decolorize enclosures, some of that characteristic parallelepiped structural signature remains; we sometimes use the word "boxy" to describe this. Such an acoustic signature is largely foreign to a musical instrument, and if noticeably present, may impair the sound.

Painstaking trials by Serblin led to the development of elaborate enclosures that moved beyond the typical box commonly tasked with containing an air space and supporting the drive units. He advanced the concept of a working acoustic structure whose behavior relating to vibration, and the resulting sound radiation, would be well-controlled and musically consonant. Even the Ancients knew that curved structures sound more harmonious and consonant with the timbre of a musical instrument. Over decades or more, there has been a search for harmony with an absence of challenging "wolf" tones.

Stereophile's Larry Greenhill interviewed Serblin at CES Chicago in June 1992. Serblin explained that in childhood, he had some experience of classical music, as his master-carpenter father had a piano. When he later came to experience the extant commercial standard of audio sound quality, he was fascinated, frustrated, and determined to do better. Thus did he pursue a lifelong personal ideal of audio perfection.

Franco's first success after establishing Sonus Faber was with the Minima, a compact, somewhat original design intended for shelf or stand. He explained that while the Minima went against the grain—or at least of then-current US ideals—of greater size and power, if optimally located in smaller spaces, it could nevertheless operate "exquisitely and musically."

Franco felt that a great design could enjoy an extended production lifetime. "We should not be enslaved to the treadmill of constant commerce-driven design renewal," he said. He revealed that the Minima was an early example of a refined, minimalist, "6dB" (crossover slope) design, which aimed to blend the driver acoustic outputs with only mild phase shifts and minimal transient overshoot or ringing for a more natural sound.

In the decades that followed, he grew Sonus Faber into a very substantial company, culminating in an expansion to a massive modern factory at Arcugano, Vicenza province. Suffering the pressures of modern business and finance, Franco changed gears (footnote 1), deciding to pursue an alternative, more easily managed enterprise, initially producing high-end silver-palladium alloy cables under his new brand Yter, in association with his engineer son-in-law, Massimiliano.

Looking back to Franco's classic Guarneri Homage, it is remarkably similar in enclosure size and driver complement to the Accordo Goldberg, as this review demonstrates, though separated by some 30 years of evolution.

The Accordo Goldberg
A more powerful loudspeaker derived from the smaller extant Accordo, the Accordo Goldberg comes with a must-have accessory: a stylishly flowing stand in black and chrome. Taking account of this loudspeaker's curvaceous, real-wood cabinetry and its eye-catching proportions, the combination is more like a luxury room accessory than our industry's typical and rather boring slab-sided loudspeaker monoliths.

But would this critic be seduced by this eye-catching creation? Initially, I was surprised by their looks, but their appearance grew on me over the review period. It is well known that even the color of an enclosure can influence opinions on sound quality. Our tests are not blind, so reviewers have to work patiently with the test sample in plain sight until possible preconceptions are dispelled and the essence of the design is revealed.

What about the stand? Although it is marketed as an "accessory," I consider it essential; much of the speaker's spatial performance quality will be lost with wall or shelf mounting. The Accordo Goldberg is no less than a sound-reproducing component engineered as Italian haute couture. If you buy the loudspeakers, get the stands.

Guided by Franco's teaching and underlying design philosophy, Massimiliano has taken up the challenge of continuing Franco's heritage (footnote 2) while cognizant of new developments in drive unit technology, enclosure design, and electroacoustic analysis. The product is now distributed in 30 countries. While building on the design premise of the smaller Accordo, with its 150mm bass-mid, this larger Goldberg variant benefits from a 180mm driver, with 44% more radiating area, from the same Scan-Speak audiophile series—mounted, of course, in a larger enclosure. Great benefit accrues from these two factors, including improved sensitivity, maximum loudness, lower distortion, and the ability to drive larger acoustic spaces. Meanwhile, it retains the elegantly slim and curvaceous proportions, remaining far removed from a conventional box: a boring old parallelepiped it is not.

My samples were ex-demo and well run in. At 16" high, a slim 9½" wide, and just less than 17" deep, this certainly is a compact design. Each solidly built speaker weighs 27.5lb, each stand 17.6lb.

Technology
For most loudspeaker driver cones, the sound-radiating element is conical in profile, the optimal shape for maximizing sound-power delivery for a given moving mass and input power. But the precise shape and profile has a profound effect on the sound. Here, one of the most respected and costly mid-bass designs has been chosen from Scan-Speak, a highly regarded Danish producer that in recent years has become an independent division of Eastech.

Near-legendary driver engineer Ragnar Lian and his colleagues had practiced their art at Scan-Speak, from the 1980s, designing low-distortion motor systems that led to many patents. Pioneering details included eddy-current–suppressing copper shading rings and caps as well as "T"-cut magnet pole pieces and low-distortion magnetic alloys. Some of these details may be regarded as precursors of the all-encompassing design approach pursued by Purifi, seen in the mid-bass driver of the recently reviewed Thrax Siren. Scan-Speak also patented that now-familiar radially curved "sliced" cone design, which sought to solve the primary higher frequency "breakup" resonance, which was embraced by Wilson Audio and many other manufacturers.

For the latest variant, the composition of the processed-fiber pulp of the cone is reinforced by the addition of mineral microspheres, for response extension and a matching increase in resolution. A final touch is a hemispherical alloy dome over the voice coil; this proverbial "dust cap" benefits the output by helping to reinforce the cone apex.

Frequencies above 2.5kHz or so are handled by the excellent D2905/970000 29mm silk-dome tweeter, also by Scan-Speak and boasting a low resonant frequency of 330Hz via an energy-absorbing rear chamber combined with a very low distortion magnet design. Both drivers are customized to specifications set by Franco Serblin, the company.

Refined over years of development to not sound like a rectangular box, the enclosure is undoubtedly special. Front, back, and sides are antiparallel and strongly curved. Massimiliano explained that structural resonances are controlled by a massively laminated construction comprising 24 solid walnut planks for each enclosure. Made in laterally symmetric matched pairs, each batch (sufficient to make 100 cabinets) is seasoned for four months before the final build, which includes laminated interlayers. The internal wiring is silver-plated copper. High-power MOX resistors fine-tune the gentle (6dB/octave) crossover slopes. The 20 liter (5.3 gallon) interior volume is damped by polyester wool and tuned by a rear port 2" in diameter and 7.8" deep, fitted with an absorbent lining of thin fiber and tuned to about 48Hz. The crossover frequency is fairly low, at about 2kHz, while the audiophile-grade crossover employs close-tolerance OFC copper wire, air-core inductors, and polypropylene-dielectric capacitors of 3% tolerance. Connection is single-wired—biwiring or biamping is not possible—via audiophile-grade WBT terminals serving spades or 4mm plugs.

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Footnote 1: After a third of a century at the company he founded, Franco enjoyed a period of retirement from that near-lifetime of research and manufacture, but then the creative urge once again took hold. In 2006, Franco started a new venture with his son-in-law, beginning with high-end precious-metal loudspeaker cables of original design (Yter), followed by the exquisitely finished Accordo compact loudspeaker. A second loudspeaker followed, the Ktêma, an ambitious floorstander with concave sidewalls, which I reviewed in 2011 (HiFiCritic Vol.5 No.3). In July 1994, I reviewed for Stereophile what could be considered the predecessor of the Accordo Goldberg: the Sonus Faber Guarneri Homage. You can read that review here.

Footnote 2: Serblin died in 2013.