The 3678-LF screen channel system can be used in either the passive mode or in a bi-amplified system. THX®-approved for THX system applications. It features low frequency transducer: One 380 mm (15 in) low frequency driver. Flat power response 100° x 100° Bi-Radial® horn. Operable in bi-amp or passive mode. Includes adjustable bracket for horn aiming. Shallow profile cabinet minimizes behind-screen space requirements. THX® - approved for THX system installations (biamplified only).