Rockford Fosgate P3D4-15 15" Dual 4-Ohm Subwoofer

The Rockford Fosgate P3D4-15 is a 15-inch dual voice coil car subwoofer designed for systems that need substantial low-frequency output. Its dual 4-ohm voice coils provide wiring flexibility for matching a compatible mono or multi-channel amplifier. It is intended for custom subwoofer enclosures rather than direct factory-speaker replacement.

With a 600-watt RMS power rating, the P3D4-15 is suited to a properly configured amplified bass upgrade. Its large cone area and 15-inch format are designed to move more air than smaller subwoofers. This makes it a practical choice for listeners building a system focused on extended bass response.

The subwoofer uses an anodized aluminum cone and aluminum dustcap to provide a rigid moving assembly. A Santoprene surround and dual-spider suspension support controlled cone movement. Its 2.5-inch, four-layer voice coil is paired with a Nomex collar for thermal durability.

Rockford Fosgate uses a StampCast basket with integrated spider venting to support the motor structure while helping air circulate around the voice coil area. The Flex Fit basket mounting pattern allows some adjustment during installation. Large nickel-plated push terminals accept up to 10-AWG speaker wire.

The P3D4-15 can be installed in either a sealed or vented enclosure, depending on available space and the desired system tuning. Rockford Fosgate specifies a 44.7-liter sealed enclosure or a 75.3-liter vented enclosure for its recommended designs. Pair it with an amplifier and enclosure built for the final impedance created by its two 4-ohm voice coils.

Key Features

• 15-Inch DVC Design: Large-format subwoofer with dual 4-ohm voice coils for flexible system wiring.
• 600W RMS Rating: Handles continuous power appropriate for a serious amplified bass system.
• Aluminum Cone Assembly: Anodized aluminum cone and dustcap help maintain cone rigidity.
• Four-Layer Voice Coil: 2.5-inch coil construction supports the subwoofer's thermal power handling.
• StampCast Basket: Hybrid basket design adds structural support while managing resonance.
• Integrated Spider Venting: Venting helps circulate air around the motor and voice coil area.

Design & Installation

The P3D4-15 combines a die-cast aluminum basket, aluminum cone, aluminum dustcap, Santoprene surround, dual spider, and aluminum voice-coil former. Its diamond-cut cast aluminum trim ring provides a finished appearance after mounting. The basket also uses Rockford Fosgate Flex Fit slot mounting for installation adjustment.

This subwoofer requires a compatible enclosure, amplifier, speaker wire, and vehicle-power installation hardware. The mounting cutout is 13.94 inches and mounting depth is 7.58 inches, so verify clearance before building or purchasing an enclosure. For a vented installation, Rockford Fosgate recommends using a subsonic or infrasonic filter to limit unusable low-frequency signal.