BLACKAIRT12S BASS ENCLOSURE. Need Bass?. The VIBE Blackair T12S Slimline subwoofer enclosure with ultra compact Powerbox400.1m Micro amplifier. Enclosure Type: Ultra Shallow Bass Enclosure. A : An active enclosure is an all in one solution where the subwoofer, amplifier and enclosure are all in one single unit making installation easy and compact.