Types of Acoustic Radiators

Diaphragms. Diaphragms are used in the receivers of common telephone sets and will be considered on page 119. Diaphragms are also used in the moving-coil motor elements for horn-type loudspeakers considered on page 114.

Cones. A double cone, with the driving element inside, was used with the type shown in Fig. 18, The cone used with the element of Fig. 19 moves back and forth, even at the outer edge and is sometimes called a free-edge cone. These cones have been made of various substances, particularly paper and similar materials, and sometimes metal.²⁹ Surprisingly wide and uniform frequency response is obtained with a loudspeaker of this type, as indicated in Fig. 21.

Figure 21. Response curve of a moving-coil loudspeaker with a thin metal cone radiator. (Reference 29.)