With more than 30 years of research in new materials for the loudspeaker diaphragm, the France based Focal introduces a new cone made of high-quality flax fibres.

Made of high-quality flax fibres core enclosed by two thin layers of glass fibre, ‘F’ cones are characterised by their natural sound, with low colouration, their richness of reproduction in the midrange register and their tighter bass.

Diaphragm technologies

The diaphragm, a critical interface for the transducer, is what sets the air molecules in motion. The fidelity of the transfer depends on the intrinsic qualities of the material used. Ideally, a diaphragm should satisfy three key criteria – it should be light, rigid and well damped.

The company currently uses two different diaphragm technologies for mid-woofers: Polyglass for the less costly ranges, ‘W’ and Kevlar sandwich, with their outstanding qualities, for the company’s top range products.

Glass sandwich for rigidity

In the course of the last few years, many innovations have appeared as a result of engineers revisiting natural materials and combining them with modern composites, thus creating new types of hybrid material.

The company’s research demonstrated that solutions using a mixture of materials offer a much wider range of possibilities that those using a single homogeneous material. The sandwich construction using thin skins of fiberglass (‘W’  sandwich), is said to remain the supreme method of controlling rigidity.

The unique qualities of flax

The core of a sandwich material provides the mechanical damping, which is responsible for the sonic neutrality of the diaphragm. Focal decided to make use of nonwoven fibres, which may make the sandwich construction available to a wider range of products.

Twice as light as fiberglass, the flax has very low elasticity which makes it ideal to increase the flexural rigidity of our sandwich. According to the company, it can be obtained in nonwoven bundles of considerable diameter and it can therefore produce the thickness required for a sandwich.

Flax is said to combine the three key factors required of the core of a sandwich material for loudspeakers: it has low density, a high tensile modulus of elasticity of up to 60GPa, and excellent internal damping.

www.focal.com