These first loudspeakers used electromagnets because large, powerful permanent Wireless Speakers magnets were generally not handy at a reasonable price. The coil of an electromagnet, called a field coil, was energized by current through a second pair of connections to the driver. This winding occasionally served a duplicate role, acting also as a choke coil filtering the function supply of the amplifier to which the loudspeaker was connected. AC ripple in the fashionable was attenuated by the action of passing through the choke coil; however, AC line frequencies tended to modulate the audio signal being sent to the cry coil and added to the audible hum of a powered-up sound reproduction device.

For example, paper is flashing and typically well damped, but not stiff; plate can be synthetic stiff and light, but it is not especially well damped; plastic can be light, but typically the stiffer it is made, the less well-damped it is. As a result, bounteous cones are prepared of some brand of composite material. This can be a matrix of fibers including Kevlar or fiberglass, a layered or bonded sandwich construction, or simply a coating applied to stiffen or muggy a cone.