The TFS-900B line array subwoofer consists of two neodymium 18" low frequency drivers in a hybrid horn-loaded enclosure, designed for ground stacking with the Flashline TFS-900H line array. The cabinet is constructed from 18mm birch plywood with IP54 rated stainless steel grille and is finished in black TourTough finish. The TFS-900B subwoofer provides sub-bass frequencies down to 35Hz. Driver maintenance can be performed without removing cabinets from the dolly because all the drivers can be accessed either from the front (the entire mid/high section is removable) or from the rear via the driver access doors. Amplification is provided in the form of the highly advanced and extremely powerful 20000DP four channel amplifiers with Lake processing and Dante networking built in. The power capability of the TFS-900H’s four frequency bands exactly matches the output of the 20000DP’s four output channels, with only four racks of three amplifiers required to deliver optimum energy transfer into a system of 18 TFS-900H tops and 12 TFS-900B subs.