When multiple drivers are used in a system, a "filter network", called a crossover, is acclimated to disjointed the incoming signal into different frequency bands appropriate for each driver. A loudspeaker system with n discrete frequency bands is described as "n-way speakers": a 2-way philosophy will have woofer and tweeter speakers; a 3-way system is either a combination of woofer, mid-range and tweeter or subwoofer, woofer and tweeter.
The diaphragm is frequently manufactured with a cone or dome shaped profile. A variety of different materials may be used, but the most frequent are paper, plastic and metal. The ideal material would be stiff (to arrest uncontrolled cone motions), polished (to minimize starting force requirements) and well damped (to reduce vibrations continuing after the signal also-ran stopped). In practice, all IPOD Speaker System three of these criteria cannot be met simultaneously using existing materials, and thus driver design involves tradeoffs.