The method of making the diaphragm includes pressing on the front face of a film at spaced apart areas to deform it progressively into a series of closely-spaced generally U-shaped projections. A manufacturing device presses the sides of the projections inwardly to rigidify them. The transducer magnet assembly includes a series of elongated magnet pole-piece strips which confine magnets and are arranged in parallel spaced-apart rows with the ends thereof fitted into transverse elongated grooves extending within a pair of elongated cross-piece end members. The driver is fixed together in a precise manner by flowing an adhesive material into the grooves, and then by allowing such material to harden.