18" Dual Passive Subwoofer System SRX828S is a dual 18" subwoofer for concert, touring, or installed use. Featuring a wide stance for splaying top boxes, indexing feet for stacking in both the standard and cardioid position, and a 141dB max SPL, the SRX828S is an ideal solution for musicians, bands, and DJs, concert use, public speaking, or installations such as performance venues, corporate spaces, educational facilities or houses of worship. Tunings and presets are available for Crown ITech HD and XTI 2 amps as well as dbx VENU360 signal processors.