The Selenium by JBL 15SWS1000 is a high power 15" professional subwoofer specially designed to reproduce sound at the very low end of the audio spectrum. This new design is capable of handling up to 1000 Watts RMS. A bumped and undercut T-yoke assures a minimum of magnetic rectification (off-centering) and a compatible maximum displacement (X-mas). The magnet assembly was designed with the assistance of a Finite Element Analysis (FEA) software in order to ensure optimization. The 4-layer copper voice coil, using over 80 grams of copper, is wound on a fibreglass-composite former, twice the thickness of typical formers, to drive the moving assembly with great rigidity. The non-pressed long fibre pulp cone has the necessary mass and stiffness to withstand the tremendous accelerating forces required, and is precisely centered by two counter-balancing, distortion cancelling, polyester cotton fibre spiders. A triple cooling system consisting of a large diameter center hole surrounded by six smaller holes (directly cooling the gap) and six frame windows (cooling the air trapped between the two spiders) are responsible for an efficient heat transfer mechanism. A highly reinforced aluminum injected frame is effective in absorbing mechanical shocks and acts as a heat sink without interfering with the magnetic field.