The SW 115E - SP is usable as an active 'Plug & Play' subwoofer for a variety of purposes when a powerful and sophisticated bass playback with high sound pressure levels is demanded. The SW 115E - SP exhibits a convincing bass supplement for many passive K&F speakers and all models of the active K&F SP-Series. Characteristics of the SW 115E - SP include its exceedingly precise bass playback, superior bass performance, compact dimensions, and sensible equipment features. The active system electronics include a convection-cooled and highly efficient digital 1 kW power amplifier. They take over the system equalisation, determine the crossover frequency, and optimise the phase response. An extensive limiter section with RMS and peak limiters provides for a high level of operating safety. The enclosure of the SW 115E - SP is equipped with stacking foot grooves and plastic feet which allow for simple stacking of several SW 115E - SP as well as combinations with the SW 215E and the full-range system Line 212. The SW 115E - SP is equipped with a 15” state-of-the-art chassis, which represents the current status of technical feasibility. Using maximal linear excursion and load capacity, it can exactly process even the highest peak pulses. An extremely stable and elaborate tunnel and enclosure construction minimise friction loss and distortion, which may occur as a result of high air velocity. The SW 115E - SP is a subwoofer system, which ideally interlinks excellent bass playback, high maximum sound pressure, and a compact design. Optimally suited for applications at the highest level.