Axiom SW218XA High Power Active Subwoofer - 2 x 18"The SW218XA generates an additional 3 dB of peak output, making it ideal for top level concert touring and festival applications requiring higher levels of low frequency response such as hard rock and electronic music. It does this by utilising the unique 4 Tetracoil, two separate voice coils wound on both side of the same former and suspended in two axially separated magnetic gaps, enabling extreme excursion of the cone and suspension system. The