SVS optimized the famous Ultra 13 driver for a sealed application by revising the motor geometry and adding a unique voice coil along with a custom gap extension plate. The result is higher thermal power handling, a more symmetrical force/displacement profile, lower distortion, and increased linear stroke. Only SVS is willing to push the envelope this far to achieve the SB13-Ultra performance goals. FEA-optimized motor with copper shorting sleeve to reduce gap induction and distortion. Unique and optimized bifilar wound, 3″ diameter, ultra-high-power aluminum voice coil. Unique gap extension plate for additional linear stroke and reduced distortion. Dual linear-roll spiders and stitched parabolic surround for extreme excursion capability.