An acoustic driver assembly for use with any of a variety of cavitation chamber configurations, including spherical and cylindrical chambers as well as chambers that include at least one flat coupling surface, is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass. The end surface of the head mass is shaped so that only a ring of contact is made between the outer perimeter of the head mass of the driver assembly and the cavitation chamber to which the driver is attached. The area of the contact ring is controlled by shaping its surface.