HK Audio LINEAR SUB 1500 A Active Sub Stereo I/O Mid/High Out X‐Over - 15"LINEAR SUB 1500 A is a 15 bass reflex subwoofer and a real powerhouse in a small package. A powerful punch, precise playback and an impressive low end all the way down to 45 Hz make this active sub the ideal add on for the LINEAR 3 mid high units when dynamic and tight bass is required. It can also be used with LINEAR 5 mid high units or as a bass extension to the ELEMENTS EASY BASE, SMART BASE and LINE BASE systems. Specifications Max. SPL @ 10% THD