Rockford Fosgate P1S4-15 15" 4-Ohm SVC Subwoofer

The Rockford Fosgate P1S4-15 is a 15-inch single-voice-coil car subwoofer designed to add substantial low-frequency output to a vehicle audio system. Its 4-ohm nominal impedance and 250-watt RMS power rating make it suited to a properly matched mono amplifier or subwoofer channel. It is intended for listeners building a dedicated bass system rather than relying on factory full-range speakers for low-end response.

This Punch P1 model uses a large 15-inch cone to move air efficiently in sealed or vented enclosures. A sealed box can support a more compact installation and controlled bass character, while the recommended vented alignment is tuned for greater low-frequency extension. The enclosure choice, amplifier setup, and vehicle acoustics will all affect final system performance.

The P1S4-15 uses a Kevlar-reinforced paper-pulp cone with an NBR rubber surround. Its high-temperature 2-inch voice coil includes a spun-laced Nomex reinforcement collar, while the motor structure uses an extended pole piece and bumped, vented backplate. These design elements support stable operation under its rated power handling.

Integrated spider venting is used to promote voice-coil cooling, and the linear spider incorporates embedded 16 AWG tinsel leads. The woofer also has custom 10-AWG nickel-plated compression terminals for secure speaker-wire connections. A heavy-gauge stamped-steel frame and protective PVC magnet cover complete the structure.

This subwoofer fits systems that have adequate enclosure volume and amplifier power for a 15-inch driver. Its single 4-ohm voice coil presents one nominal 4-ohm load to the amplifier. It can be used as the bass section of a system with aftermarket speakers and a compatible amplifier, with enclosure construction and crossover settings selected for the vehicle and installation goals.

Key Features

• 15-Inch Driver: Large cone area supports dedicated low-frequency reproduction.
• 250-Watt RMS Rating: Matches amplifiers rated appropriately at 4 ohms.
• 4-Ohm SVC Design: Provides a single nominal 4-ohm amplifier load.
• Kevlar-Reinforced Cone: Reinforced paper-pulp construction supports cone rigidity.
• Spider Venting: Helps promote airflow around the voice coil.
• 10-AWG Terminals: Nickel-plated compression terminals accept substantial speaker wire.

Design & Installation

The P1S4-15 combines a Kevlar-reinforced paper-pulp cone, NBR rubber surround, high-temperature voice coil, and heavy-gauge stamped-steel frame. It also uses an extended pole piece, bumped vented backplate, protective PVC magnet cover, and soft-touch ABS trim ring. The trim ring is designed for use with an optional grille.

Allow for the 13.85-inch cutout diameter and 6.98-inch mounting depth before selecting an enclosure or mounting location. Rockford Fosgate specifies a 1.58-cubic-foot sealed enclosure or a 2.66-cubic-foot vented enclosure, with the vented alignment using a 4-inch-diameter, 10.8-inch-long port. Use an amplifier and wiring arrangement appropriate for a single 4-ohm, 250-watt RMS subwoofer, and set the system crossover and gain carefully during installation.