Dayton Audio SPA250 250 Watt Subwoofer Plate Amplifier Engineered to provide flexibility, ample power, and reliability, the Dayton Audio SPA250 delivers high fidelity subwoofer amplification and is tailored for home audio and home theater audio systems. - Product Highlights - Switchable 6 dB @ 35 Hz bass boost - Mono Class AB output stage for solid, well defined output - Low-level, high-level, and LFE inputs connect to any system - Manual, auto, or triggered on/off modes for compatibility with any automated system - Variable gain, crossover point and switchable phase controls optimize room integration - Switchable 115/230V input voltage - Energy efficient draws less than 1 watt in stand-by mode The Dayton Audio SPA250 subwoofer amplifier produces 250 watts of clean power output, and combines with a host of flexible user options to make it an unbeatable choice. A user-configurable bass boost circuit creates a 6 dB peak at 35 Hz, which allows sealed subwoofer designs and certain ported enclosures to achieve their optimum bass extension and maximum "flat" output. The SPA250 features RCA line level and banana jack speaker level inputs and outputs, automatic power-on that is triggered by any audio input signal, and a phase reverse switch to match the subwoofer to your room and your other speakers. A single amp can accept a stereo input signal and combine it into mono, which is preferred for sub bass reproduction. A preamp or receiver's LFE output may be connected to the SPA250's Left (mono) input. The internal low pass crossover is fully adjustable between 40 and 180 Hz, and of course the amp has built-in protection against internal and external faults. Variable low-pass filter at 24 dB/octave attenuation from 40 Hz ~ 180 Hz - Switchable phase 0° (NOR) or 180° (REV) - Variable gain MIN/MAX input voltage dependent - Speaker level high-pass outputs 6 dB/octave at approximately 90 Hz @ 8 ohms, 180 Hz @ 4 ohms (i.e. 220 uF electrolytic capacitor) - Line-level full bandwidth (10 Hz- 20 kHz) outputs/throughputs for adding or "daisy chaining" additional amplifiers - Subsonic filter 12 dB/octave high-pass filter centered at 20 Hz - Damping factor at rated power: 114 @ 100 Hz Specifications: Measured power output: 156 watts RMS into 8 ohms @ 0.1% THD, 252 watts RMS into 4 ohms @ < 1.0% THD Signal to noise ratio: 90 dB A-weighted Input impedance: 10.4K ohms Bass boost: Switchable, 6 dB @ 35 Hz Low pass adjustment: 40 Hz to 180 Hz Phase adjustment: 0 (normal) 180 (reverse) Power requirements: Switchable, 115/230 VAC, 60/50 Hz Dimensions: 9-13/16" W x 9-13/16" H x 5" D Cutout dimensions: 8-1/2" W x 8-1/2" H.