Yamaha SW10

Yamaha SW10 ... response down to well below the audible limit. The SW10 features a newly designed long-stroke 25-cm (10"") woofer which achieves exceptionally smooth, accurate low-frequency reproduction, while a built-in high-performance 180-watt power amplifier delivers solid, highly damped power. A variable low pass filter (40 Hz ~ 120Hz) makes it easy to achieve optimum crossover with just about any main speaker system, and a built-in phase switch allows instantaneous phase reversal without having to modify cables or connections."