HK Audio LINEAR SUB 4000 2400-Watt Passive Subwoofer - 2x18"Description L SUB 4000 A LOW END BOOST FOR THE LINEAR SERIES L SUB 4000 is a powerful 18 double vented bandpass subwoofer. Compatible with all LINEAR 5 fullrange speakers and mid high units, its powerful low end ranging from 30 to 100 Hertz is totally and powerfully impressive. L SUB 4000 A can also serve as a sub low add on to LINEAR SUB 2000 to beef up the bottom end when required (optional frequency separation). Filter presets are available for