The Dome refers to the convex hemispherical shape of the diaphragm used in most tweeters and some midrange speakers. Unlike cones, which are driven from the center, domes have the voice coil attached to their outer circumference. There are two main construction categories that define the sound. Soft domes, usually made of silk or treated fabric, are known for a smooth and natural treble response. Rigid domes, manufactured with light metals such as aluminum, titanium, or beryllium, offer greater rigidity and frequency extension, resulting in a more analytical and bright sound.