Compact Line Array System. This Unique Product Allows The Venue’s Main Pa Or Music System. The VD-18S from VL AUDIO designed to deliver an unprecedented combination of sound quality, portability and durability at it’s price point. The subwoofers pack powerful low-frequency output into a surprisingly compact footprint and feature tuned 20 mm. thick wood enclosures with a water based textured coatings finish. The VD-18S using 18′′ low frequency transducer employing a 302 mm (18′′) voice coil and neodymium magnet motor assembly.