Abstract: An electrodynamic transducer has broadband operation and is suitable for erwater use. The transducer has a flexible rubber seal to assist in keeping the unit watertight. New features include a large flared air passage, a coil of wire that is rectangular in cross section and is routed through the center of a hollow centering shaft. In addition, a piston is machined out of beryllium copper with the piston attached to the shaft at the dome center and the skirt spider center. The transducer is designed to operate with the magnet having its outer pole piece in contact with the seawater.