Made of a specially blended, highly durable and moisture-resistant compound, butyl rubber keeps the cone moving in a linear direction, seals the cone to the basket and quickly dampens cone vibration once the signal has changed or stopped.  This results in less distortion and superior frequency response.

Polypropylene (PP) is a tough thermoplastic resin that is an ideal material for a subwoofer cone – with low mass and high damping, PP cones offer good sensitivity and low distortion.  However, polypropylene cones lack the rigidity and strength required for high output and extreme low bass.  To resolve this, Pioneer engineers using advanced Computer-Aided Manufacturing, developed a process to blend aramid fibers into the polypropylene resin during the injection molding process. The resulting Aramid Fiber Interlaced IMPP subwoofer cone is incredibly strong and low mass with high rigidity and superior strength to produce deep, powerful and undistorted bass.

A subwoofer motor structure consists of the voice coil and magnet assembly.  Increasing the diameter and length of the voice coil provides greater control of the woofer cone and higher power handling.  However, to take full advantage the magnet must also be increased, both in magnetic power and physical size.  The D subwoofer uses an oversized 4-layer voice coil and high energy double stacked magnets to increase the overall power handling and SPL output with no sacrifice in sound quality.