duet ® two-piece speaker system The JBL Duet multimedia system provides smooth and accurate sound for any portable music player or computer. With its incredibly easy setup and use, Duet is a sophisticated approach to achieving great two-channel sound. Technology Duet uses patent-pending Tangential Strain Relief (TSR™) transducer technology. With TSR, Duet delivers extra bass and lower distortion as a result of controlled linear excursion of the speaker.