an audio transducer having a cylindrical diaphragm molded with contoured ridges . the diaphragm includes at least two lobes , each extending from a central expanse to the transducer frame . the lobes may have different radii and different angular arc lengths . a driver attached at the central expanse may include a double - sided etched coil , or may be provided by an electrostatic driver having a charged filament attached to the diaphragm . the transducer diaphragm may include a central third lobe having different size and structural characteristics to provide added low frequency response . the transducer may be configured to provide omnipolar sound radiation with opposed spaced - apart semi - circular cylindrical diaphragms arranged to pulse symmetrically toward and away from each other .