Sonus Faber Concerto Grand Piano loudspeaker
So here's a pair of Sonus Fabers that stand on their own two feet, are graceful-looking but not "wooded out" to the max, and, at $3500/pair, would seem to be reasonably priced. How could I say no to a review opportunity?
I couldn't. And I'm glad I didn't, both because my months with the Concerto Grand Piano were musically satisfying, and because it gave me an opportunity to learn more about Franco Serblin's company and why he opts for all that fancy wood. One thing I did learn: the company's incredibly sexist! The Grand Piano's owner's manual begins "Dear Sir..." Puh-leeze!
The Grand Piano is the top of Sonus Faber's "affordable" Concerto series (see Martin Colloms' review of the Concerto in the January 1998 Stereophile), and the company's first and only floorstanding speaker. According to Sonus Faber's product literature, a love of violin making inspired the woodworking excellence—and not merely for its physical beauty. Rather, the company sees the speaker baffle as "an instrument which amplifies sound, not merely a container of sonic power with technically approved dimensions."
Is that an admission that its baffles "sing"—something no speaker designer with whom I'm familiar would advertise? I don't think so. I think it's more company "color" than anything else, though the cabinets of the expensive Sonus models differ from most others in that they're built from solid, seasoned (dried two years in a kiln) wooden staves, or slats, which are chosen one by one "so as to control the harmonic structure of the resonances." I'm not sure how one does such choosing merely by looking at a slat of wood, but it means both beauty and expense: each chosen stave must be clamped and hot-glued to the next, and finally hand-sanded and varnished like a fine violin.
Why are the cabinets so constructed? Because using solid wood would create seriously nasty resonances. That's why most speakers are made of far stiffer and less expensive MDF. Sonus uses solid wood, but by slicing it up, "jointing" it, and gluing the pieces together in vertical slats, stiffness is increased and resonances are broken up. And, of course, it makes an impressive interior-decorating statement.
To cut costs, the Concerto line uses a simpler design structure that calls for an ultra-rigid MDF top, bottom, front, and back to be built first, then covered in black leatherette. The side panels, fabricated from 1"-thick contoured MDF and finished in gloss-black lacquer, are acoustically decoupled by the folded-over leatherette. They're screwed in and glued, the goal being to reduce the low-frequency acoustic influence of the large, flat side panels on the drivers.
The Grand Piano is a two-way design utilizing a 7" acrylic-treated paper-cone woofer designed to SF's specs by SEAS, crossed over at 2.3kHz via a first-order (6dB/octave) filter to a ¾" silk-domed, ferrofluid-cooled SEAS tweeter. A 7" passive radiator with a textured cone surface controls the bass backwave.
While a two-way design with gentle slope filters gives you the advantages of simplicity, it also means the woofer is operating outside its ideal bandwidth, and is being asked to deliver the goods well into the treble. So, to add stiffness to the cone and optimize high-frequency dispersion, the 7" driver is fitted with a concave brass phase plug. According to the accompanying literature, a great deal of attention has been paid to the long-throw motor design to ensure linear behavior, particularly in the transition between forward and rear motion.