Technology in Thin Ply Carbon Diaphragms

Combining ultralight weight, high stiffness and controlled break up behavior

Thin ply carbon is not one material with one set of properties, it is a technology that enables the engineering of an infinite number of materials with different properties that can be constructed in diaphragms in yet an infinite number of ways.

A speaker cone made from metals such as aluminum or titanium have the same material properties in all directions, and will therefore experience symmetric and severe break up modes around the cone. Such symmetric modes can be reduced by breaking the symmetry in the diaphragm, as Bowers & Wilkins pioneered with their yellow aramid (Kevlar) cones. With thin ply carbon diaphragm technology, this can be taken several steps further. Not only is the symmetry broken but the fiber architecture and the diaphragm can be engineered to optimize and control the break up behavior.

By optimizing the fiber architecture, the symmetric break up modes are replaced with more but smaller and local break up modes. This creates a distributed break up with smaller peaks in the frequency response and ultimately a smoother and more natural sound without harshness. Due to the ultralight weight and very high stiffness, high frequency diaphragms are also made using thin ply carbon technology.

The symmetric break up modes in a titanium compression driver vs distributed break up modes in a thin ply carbon compression driver diaphragm.

 

The effect on the frequency response curve is shown below. The big peaks of the hard diaphragm (for instance titanium or aluminum) in gray are replaced with more but smaller peaks in the thin ply carbon diaphragm in green. Furthermore, higher stiffness to density ratio as well as the distributed break up is shown as the break up is moved up in frequency. The lower moving mass of the thin ply carbon diaphragm results in higher sensitivity.