The drivers in the Prelude MTS all have the acronym CMMD-it means a cone and dome material using a ceramic/metal matrix of two outer layers of pure alumina bonded to an internal substrate of low-density aluminum. Infinity says that the alumina ceramic compound is three times as "dead" as titanium and 85 times stiffer than felted paper, and that the differential between the ceramic outside layer and aluminum substrate provides additional damping that soothes frequency peaks.