The P18Si is producing awesome low-frequency energy, its pure visceral bass fills small and medium rooms with seemingly unlimited headroom. The P18Si is the only subwoofer for those seeking the aural immersion of the reference cinema and live concert experience. The P18Si is basically half of the famous P18 with a stunning 127 dB (133 dB peak) output capability, and sub-bass extension to down below 18Hz. The P18Si can also be used as a balancing subwoofer which enables the use of multiple subwoofers in multiple locations to produce more consistent seat-to-seat bass performance. With a relative small footprint for maximum flexibility, the P18Si can optimize low frequency per- formance in combination with any Procella subwoofer. When properly applied using DSP, this technique improves the system’s overall bass quality and significantly reduces the seat-to-seat variance in low frequency levels found in small rooms using a single subwoofer.