The PS18 is the sole passive subwoofer in the pulse line. Bi-amping is of course an option, but not a necessity due to an internel 150Hz low-pass network. With power handling of 300 W, the PS18 may be used independently or in parallel with mains. A single, custom designed cast frame 18" Eminence speaker assures tight control and excellent linear response. With a lighter weight and more compact size then many other 18 inch subwoofers, the PS18 is an excellent choice when you want Pulse quality, performance and appearance in a passive subwoofer.