A low‐frequency sound source of high acoustic output (214 dB re 1μPa at 1 m) has been developed by Hydroacoustics Inc. The projector has been configured to operate over two distinct frequency bands, with a bandwidth of approximately 40\% of each band-center frequency. The conversion between the two bands requires relatively simple hardware changes, principally in the radiating structure. The primary input power to the source is in the form of three-phase electrical power to an electric motor driven hydraulic power supply which is an integral part of the projector structure. Conversion of the input power to acoustic energy is accomplished through a rugged hydroacoustic power amplifier which responds to a low level signal voltage and reproduces this waveform as acoustic pressure/flow acting in a centrally located fluid cavity. Two opposed, edge-supported radiating flexural disks are center driven by drive pistons which communicate with this fluid cavity. The entire structure is very rugged and capable of operation to great depths. 

        Analytical modeling of this projector has been developed by the Naval Ocean Systems Center in conjunction with Hydroacoustics. This model includes the radiation loading, the flexural modes of the radiating disks, the hydraulic power supply, and the two stage hydraulic amplifier-including those nonlinearities associated with large power transduction. In water calibration test results in both bands will be presented, as well as a comparison between these results and the modeling effort. [Work supported by the Naval Electronics System Command.