2003

Sonus Faber Stradivari: Design And Specifications - Part Iv



Ricardo Franassovici, Franco Serblin and Stradivari


 


Sonus Faber has always striven to keep the baffle to a minimum to prevent diffraction and improve focus to the point of modelling the cabinets “around” the drive units. The Stradivari is a departure from this concept in the manner of some Infinity models of yore as reminded by Ken Kessler at breakfast.


 


Stradivari Red Violin


 


The virtual 2 pi radiating infinite baffle is based on the concept/surface of the “piano armonico” of the violin which allows the midrange unit to reach its lower frequency limit in a more poised and natural way, thus conveying to the listener a sense of better integration with the massive double bass drive units.


 


The Stradivari is a 3-way elliptical design, a first for Sonus Faber (by first I mean the ellipticall shape, since the Amati is also a 3-way design). All units have their own loading chambers, with ports open in the back in the case of the midrange and low frequency units. The curved external walls are made of multiple layers of wood with special attention to internal damping for minimum coloration and reinforcing ribs for maximum stiffness. Wood density, quality and grain orientation of each layer has been optimised to distribute and virtually eliminate resonances. The special lacquer used is based on the great Maestro Stradivari's original recipe and said to be “friendly” to acoustics.


 


Stradivari Nera


 


The finishing is to the usual high standard of the Homage Series: slightly more red and less orange than the Amati; there will be a “Nera” version in a more discrete greyish shade of black. Maybe a little too discrete for some tastes.


 


The tweeter is a revamped version of Larsen's dual pole Vifa unit (the same used by Krell in the LAT Series), designated here as “The Silk Ring Radiator”. It has a broader bandwidth and a wider dispersion than the metal units while still keeping the advantages of the dome diaphragms. The dual-wave diaphragm frontal radiation is controlled by a toroidal wave guide (a special phase plug designed by Sonus Faber). The rear radiation is tamed by a dedicated wooden acoustic labyrinth.


 


The middle frequency system is the key to the superb sound of the Stradivari. The 150mm transducer is handmade by a Danish artisan and was chosen for its high dynamic linearity being responsible for the reproduction of the human voice (the essence of communication among humans as Franco points out). The main element and literally the “soul” of the Stradivari acoustic system is also one of the most fundamental “pieces” of the violin: the “Anima” (or “soul”). The “Anima” is a small wooden part - apparently insignificant - device that connects internally the top surface of the violin body to the bottom surface. Like us, humans, without its “soul” a violin is dead to the music. And like with Antonio Stradivari in its own time, to whom Franco Serblin pays finally its long due tribute, the rest is a secret…


 


For low frequency reproduction two aluminium/magnesium 260mm cones are used, their surfaces coated with a unique elastic membrane to further eliminate colorations. The low frequency system is tuned to the volume of the main shell, while the middle and high frequency units are decoupled from the main shell by a separate sub-baffle.


 


The crossover, encapsulated in a vibration inhibiting resin mould, uses a multi-slope structure to control both amplitude and phase over the whole audible spectrum, a departure from the 2-way first order crossovers, for which Sonus Faber is better known. The transition cut-off frequencies follow the psychoacoustics of the human voice at 300Hz and 4000Hz. The unusually high upper frequency cut-off accounts for the seamless transition between midrange and tweeter as the majority of acoustic instruments have their fundamentals below 4000Hz.


 


Specifications


 


Sensitivity: 92 dB, 1W/1m


 


Impedance: 4 ohms nominal


 


Power : Minimum 30W, Maximum 300W without clipping


 


Frequency response: 22Hz - 40kHz


 


Dimensions: W 650 - D 500 - H 1360 mm


 


Weight: 150 Kg pair without packing


 


195 Kg pair with packing


 


Price and availability: (aprox) €30.000 in Europe; Jan/Feb 2004


 


(1) Based on the Sonus Faber Stradivari brochure