The Sonus faber’s drivers evolution by Paolo Tezzon

The Sonus faber’s drivers evolution told by paolo tezzon, r&d manager (Midranges and midwoofers): “…It assumes that our main goal is to achieve the naturalness of music reproduction. After several years of experiments, and after having tested other solutions, we came to the conclusion that, despite the various Hi-Fi fashions, only using diaphragms based on natural materials it is possible to reach the most natural sound presentation.

This is why we choose paper pulp as the fundamental ingredient of our cone drivers, which are designed and built in our Vicenza-based headquarter.

When the choice for paper was set an endless process of research and listening sessions allowed us to understand two more important things…
The first one: the cone production process has a huge impact on the sound, particularly, the air drying technique is able to provide the best results in terms of naturalness.
The second one: adding natural fibers to the cellulose mix allows to fine tune the sound, balancing transparency, damping and rigidity. This discovery lead us to an never-ending path of experiments and research that keeps going on today.
The final touch of our cone optimization process is the “hidden” coating treatment.
The backs of the cones are sometimes hand-coated by our skilled artisans with an “old secret cocktail recipe” of special resins in order to obtain an additional selective and tuned damping.
We do this treatment on the “dark side” of the cone, leaving the emitting surface untouched, to preserve maximum transparency and ability of revealing even the most tiny details hidden in the music presentation…
“…Certainly, when it comes to purely low frequencies reproduction the optimal solution is a diaphragm being extremely rigid and extremely lightweight at the same time.
Now is clear that Sonus faber’s favorite material for mid frequencies diaphragm cones is paper.
Unfortunately a pure paper cone wouldn’t be stiff enough for optimal bass reproduction.
This is the “central point” which led the R&D team to push forward innovation being among the first to use a “sandwich cone construction” that combines 2 treated skins – made in cellulose – with a layer of syntactic foam in between.
Which are the benefits?: while the outside cellulose skin is perfectly matching – from a tone standpoint – the midrange sound, providing a coherent result, the sandwich construction with foam gives to the cone amazing rigidity in a lightweight package, which is perfect for a woofer’s “pistonic behavior” .
When it comes to big diameters extreme performance subwoofer drivers – to be used in the very low frequencies, where the tonal coherence is no more an issue and where heavy excursions are the main job – the sandwich construction still provide the perfect solution: it’s just a matter of using carbon fiber (Nano carbon fiber in our case) skins instead of the cellulose ones and the result is the most rigid cone possible.”