The diaphragm, the key component of a loudspeaker, is at the heart of our acoustic engineers' research. Polyglass technology, exclusive to Focal, consists of applying fine glass microbeads to a cellulose pulp cone. This process reconciles the excellent damping of paper with the rigidity of glass. The stiffness index is almost 10 times that of polypropylene. Adjusting the mass-rigidity-damping ratio results in a remarkably linear frequency response curve, right from the membrane design stage. This innovation also significantly increases definition in the midrange register.