The presentation describes the design and test of innovative deep water low frequency sound source for long range acoustic communications and navigation. The light-weight, low frequency (200–1000 Hz), broadband underwater sound source comprises an inner resonator tube with thin walls tuned to a certain frequency surrounded by a shorter, larger-diameter, lower frequency tuned outer resonator tube. These resonating tubes are opened on both ends and made of carbon fiber. The tubes are asymmetrically shifted along the main axis and sound pressure can penetrate from internal pipe though the area under the shifted external pipe into that external pipe and back. By changing length of shifted area the coupling coefficient of two resonators can be regulated to achieve a necessary bandwidth. The design uses depth independent oil-filled acoustic transducer. The transducer is light, operational for all ocean depth, and reasonably broadband. A multiresonant systems usually need a precise complicated adjustment of their parameters to get necessary bandwidth with limited variability of frequency response inside the frequency range. It can be even more complicated, when design includes new, never tested before, materials. Application of finite element analysis allowed to predict necessary parameters and avoid a long series of water tests with parameters adjustment.