Rockford Fosgate T1D412 12" Dual 4-Ohm Subwoofer

The Rockford Fosgate T1D412 is a 12-inch Power Series subwoofer designed for car and truck audio systems that need substantial low-frequency output. Its dual 4-ohm voice-coil configuration provides wiring flexibility for matching a compatible mono amplifier. With 800 watts RMS power handling, it is suited to systems built around a properly set up external subwoofer amplifier.

This model is intended for listeners who want deeper bass extension without moving to a larger driver size. Its 12-inch format can work in sealed or ported enclosures designed to the manufacturer's recommendations. The dual voice coils can be configured for either a 2-ohm or 8-ohm final load through the integrated SWIFT terminal system.

The T1D412 uses a Kevlar-fiber-reinforced paper cone and a VAST Santoprene surround. VAST, or Vertical Attach Surround Technique, increases effective radiating cone area compared with a conventional surround attachment. The result is a driver that uses more of its frame diameter for active cone area.

Thermal and mechanical design details include an anodized aluminum voice-coil former, copper-clad aluminum voice-coil wire, a heat-sinking aluminum dust cap, and optimized pole-piece and spider venting. The IDHS inductive damping heat sink is part of the motor assembly. These elements are intended to manage heat and support controlled operation at higher power levels.

The T1D412 is a practical fit for a dedicated bass upgrade in a sedan, SUV, truck, or custom enclosure project. Rockford Fosgate publishes sealed and ported enclosure recommendations, allowing the system to be tailored for compactness or deeper vented-box output. A correctly matched amplifier, enclosure, wiring, and tuning are necessary to use the subwoofer within its rated capability.

Key Features

• 800-Watt RMS Handling: Supports amplifier matching up to its continuous 800-watt rating.
• Dual 4-Ohm Voice Coils: Enables 2-ohm or 8-ohm final impedance configurations.
• VAST Surround: Increases effective radiating cone area by up to 25%.
• SWIFT Terminals: Simplifies series or parallel voice-coil configuration at the subwoofer.
• IDHS Heat Sink: Helps manage motor-system heat and reduce inductive effects.
• Die-Cast Aluminum Frame: Provides a rigid mounting structure for the driver assembly.

Design & Installation

The T1D412 combines a rigid die-cast aluminum frame with a Kevlar-fiber-reinforced paper cone, Santoprene surround, dual progressive-roll poly-cotton spiders, and an anodized aluminum dust cap. Its 3-inch high-temperature dual voice coil uses a spun-laced Nomex reinforcement collar and aluminum former. Periodically stitched tinsel leads and optimized pole and spider venting are incorporated into the driver design.

Plan for an approximately 11.22-inch cutout and 6.99-inch mounting depth, while also allowing enclosure clearance behind the motor and wiring terminals. Rockford Fosgate specifies a 1.25-cubic-foot sealed enclosure or a 1.75-cubic-foot ported enclosure tuned to 40.1 Hz with a 4-inch-diameter, 9-inch-long port. Use an amplifier and wiring configuration that match the selected 2-ohm or 8-ohm final load, and set gain conservatively to avoid distortion.