The MSE-218 is a high-power subwoofer system, designed to fulfil the most demanding applications where scalability and single-enclosure use are as important as sonic performance.  MSE-218 subwoofers are inherently scalable – they can be used as single units, or in large numbers for filling arena or stadium shows.  The substantial enclosure houses a pair of reflex-loaded 4.5” voice coil, 18” (457mm) neodymium LF cone drive units.  Like all EM Acoustics products, headroom is key.  Peak-to-peak linear cone travel is 28mm, meaning large amounts of low frequency information can be produced by a surprisingly small and lightweight subwoofer enclosure. The MSE-218 requires an active crossover to function correctly – although the choice of filter points is very wide, allowing the user to tailor the response to exactly what is required.  Cardioid DSP program settings are also available to create arrays with significant rejection to the rear of the subwoofers, by stacking three enclosures in a block (two facing forwards, one facing backwards). The robust enclosure is constructed from premium multi-laminate Birch plywood and is finished in impact resistant paint.  The enclosure is finished in black as standard, however RAL colour matching as well as weather protection options are available.  Runners are provided on the bottom of the enclosure to protect the paint finish when in use, and recesses on the top of the enclosure allow stable stacking of arrays.  Eight steel bar handles and tour-grade castors are also fitted as standard.  A pair of M20 threaded flange adapters are provided in the top of the enclosure for mounting fullrange products above for compact systems.  The front of the enclosure is protected by a rigid steel grille. The MSE-218 requires active high/low pass filters and a single amplifier channel capable of delivering 3000-4500W RMS into a 2 ohm load.  For best results, the EM Acoustics AD-9 amplifier should be used.