An Alpine power subwoofer is for audiophiles who demand big bass but don’t have the space for a big speaker. Powered car subs have both the woofer and a mono amplifier in a compact enclosure. They’re great for upgrading a factory audio system and don’t require buying a separate amp. Most can be installed under or behind the seat! Order a universal or vehicle-specific Alpine active subwoofer from OnlineCarStereo.com with a low price guarantee.