Rockford Fosgate M1D4-8B 8" Marine LED Subwoofer

The Rockford Fosgate M1D4-8B is an 8-inch marine subwoofer designed to add low-frequency support to boat and powersports audio systems. Its dual 4-ohm voice-coil design uses an integrated VersaSwitch to select a 2-ohm or 8-ohm final impedance. This helps simplify matching the subwoofer to a compatible marine amplifier.

Rated for 150 watts RMS and 600 watts peak, the M1D4-8B is intended for systems that need controlled bass without requiring a large subwoofer opening. Its 20 Hz to 750 Hz frequency response covers the lower range that full-range marine speakers do not reproduce as strongly. The 8-inch format is useful where available mounting space is limited.

Color Optix RGB lighting is integrated into the black grille assembly for illuminated system styling. The lighting can connect to a Rockford Fosgate Color Optix controller and the RF Connect App for adjustable color patterns. A PMX-RGB controller is required for full Color Optix control and is sold separately.

The M1D4-8B is built for marine and motorsport environments with an Element Ready design and IP67 certification. Its mineral-filled polypropylene cone, Santoprene VAST surround, UV-stable ASA plastic frame and grille, and corrosion-resistant terminals support outdoor installation. The vented motor uses a water-repelling nano-coated mesh screen.

For a complete marine audio upgrade, this subwoofer can be paired with a compatible mono or multi-channel marine amplifier and Color Optix-equipped speakers. Integrated Deutsch and Amphenol connections support organized speaker and lighting integration. The selectable impedance switch allows the installer to configure the subwoofer for the amplifier's supported load without conventional series or parallel voice-coil wiring.

Key Features

• 150-Watt RMS Handling: Supports amplifier matching for sustained bass output.
• VersaSwitch Impedance Selection: Selects a 2-ohm or 8-ohm final load.
• Color Optix RGB Lighting: Adds configurable multicolor illumination to the grille.
• IP67 Element Ready Design: Built for water, UV, vibration, and marine exposure.
• 8-Inch DVC Subwoofer: Fits compact marine and powersports bass installations.
• VAST Santoprene Surround: Increases effective cone radiating area while maintaining durability.

Design & Installation

The M1D4-8B uses a co-molded mineral-filled polypropylene cone and Santoprene surround, with linear synthetic-fiber blend spiders and a 1.5-inch four-layer voice coil. Its black ASA plastic frame and grille are UV-stable, while the terminals are zinc-nickel-plated marine-grade brass. The integrated RGB lighting uses optically clear UV-stable encapsulation and wide-angle tri-color SMT LEDs with flat molded lenses.

Confirm a 7.10-inch mounting cutout and at least 3.43 inches of mounting depth before installation. Use the VersaSwitch to choose the 2-ohm or 8-ohm configuration that matches the amplifier, and connect the lighting harness to a compatible Color Optix controller for app-based color control. The package includes the subwoofer, attached illuminated grille, LED power harness, mounting screws, drill bit, Allen bit, and documentation.