The passive JBL Professional 4739 Subwoofer is the bass module used in the 3733 and 4722 ScreenArray Cinema Loudspeaker Systems, which provides superior coverage, maximum power handling, and uniform acoustic power output, along with low distortion. The low-frequency enclosure features two patented Differential Drive 15" low-frequency woofers for improved power handling and reduced distortion. The shallow profile of the JBL 4739 is ideal for minimum behind-screen depth requirements.