Rockford Fosgate RM112D4B Prime Marine 12" Dual 4-Ohm Subwoofer 12" Marine Bass, 2-Ohm Ready, Black Finish

Product Overview

The Rockford Fosgate RM112D4B is a black 12" dual 4-ohm subwoofer from the Prime marine range, purpose-built for marine watercraft and powersport applications. The 2-ohm stable counterpart to the RM112D2, the RM112D4B delivers the same 12" Prime marine subwoofer performance and complete true marine-grade construction in a dual 4-ohm voice coil configuration wiring in parallel for a 2-ohm load for direct pairing with 2-ohm stable mono amplifiers, or in series for an 8-ohm load for specific system configurations.

Sharing every material and construction specification with the RM112D2 100% UV stable ASA injection-moulded plastic parts, UV and salt-fog resistant Santoprene surround, injection-moulded mineral-filled polypropylene cone with UV inhibitors, moisture and fatigue-resistant Aramid fibre spider, ultra-flexible silicone lead wire, and proprietary corrosion-resistant spring-loaded push terminals the RM112D4B is differentiated solely by its dual 4-ohm voice coil configuration. Compatible with sealed, vented, and infinite baffle installations. Colour-matched black grille and removable trim ring included.

Key Specifications

• Driver size: 12"
• Voice coil configuration: Dual 4-ohm (DVC)
• Wiring options: 2 ohm (parallel) / 8 ohm (series)
• Enclosure compatibility: Sealed / vented / infinite baffle
• Plastic parts: 100% UV stable ASA injection-moulded
• Cone: Injection-moulded mineral-filled polypropylene with UV inhibitors
• Surround: UV and salt-fog resistant Santoprene
• Spider: Moisture, tear and fatigue-resistant Aramid fibre
• Lead wire: Ultra-flexible fully insulated silicone
• Input terminals: Proprietary corrosion-resistant spring-loaded push terminals
• Grille: Colour-matched black (included)
• Trim ring: Removable (included)
• Colour: Black
• True marine-grade compliant
• Power handling: Confirm with supplier
• Frequency response: Confirm with supplier
• Sensitivity: Confirm with supplier
• Mounting depth: Confirm with supplier
• Cutout diameter: Confirm with supplier
• Shipping weight: Confirm with supplier

Features & Benefits

• Dual 4-ohm voice coils 2-ohm parallel or 8-ohm series wiring: The key differentiator from the RM112D2. Wired in parallel, the RM112D4B presents a 2-ohm load the natural pairing for 2-ohm stable mono amplifiers including the Rockford Fosgate PM300X1 Punch Marine 300W mono amplifier. Wired in series, it presents an 8-ohm load for specific multi-driver or bridged configurations. Choose the RM112D4B for 2-ohm stable amplifier pairings; choose the RM112D2 for 1-ohm stable amplifiers.
• 12" driver diameter more cone area than the RM110 10" range: At 12 inches, the RM112D4B moves significantly more air per unit of excursion than a 10" marine subwoofer, producing deeper low-frequency extension and higher output levels from the same amplifier power the natural choice for vessel and powersport builds where maximum marine bass performance is the priority and 12" diameter fits the installation.
• True marine-grade compliance: Meets Rockford Fosgate's true marine-grade standard with every component purpose-selected for UV, salt fog, moisture, and vibration resistance engineered for the outdoor marine and powersport environment from the component level up.
• 100% UV stable ASA injection-moulded plastic parts: ASA engineering thermoplastic specifically formulated to resist UV-induced colour fading, surface degradation, and structural embrittlement under prolonged direct sun exposure on Australian watercraft and powersport vehicles.
• UV and salt-fog resistant Santoprene surround: Santoprene thermoplastic rubber maintains consistent mechanical compliance under UV radiation and salt fog exposure where conventional rubber surrounds crack and foam surrounds degrade directly contributing to long-term subwoofer performance and reliability in marine environments.
• Injection-moulded mineral-filled polypropylene cone with UV inhibitors: Mineral filling increases cone stiffness and dimensional stability, resisting moisture absorption and maintaining pistonic accuracy at high excursion levels. UV inhibitors prevent polymer chain degradation under direct sun exposure.
• Moisture, tear and fatigue-resistant Aramid fibre spider: Resists moisture absorption that would alter compliance characteristics in wet marine environments, providing superior tear and fatigue resistance during high-excursion 12" subwoofer use.
• Ultra-flexible fully insulated silicone lead wire: Maintains flexibility across the wide temperature range of Australian outdoor environments, resisting cracking and hardening in conditions where standard PVC insulation degrades over time.
• Proprietary corrosion-resistant spring-loaded push terminals: Fast, tool-free wiring connection with corrosion resistance appropriate for saltwater and estuarine environments where standard binding post materials accelerate galvanic corrosion.
• Sealed, vented, and infinite baffle installation compatibility: Confirmed compatible with free-air (infinite baffle) installation allowing direct mounting in vessel transom panels and powersport enclosures where a dedicated subwoofer box is impractical, consistent with the full RM1 Prime marine subwoofer range.
• Black finish with colour-matched grille: Black finish and 100% UV stable colour-matched black grille suit darker vessel interiors, black-trimmed marine audio installations, and powersport builds where a black aesthetic is preferred. The ASA material specification maintains black finish integrity under prolonged UV exposure.
• Available in black or white: The RM112D4B is the black finish variant. A white finish version is available separately confirm part number with your supplier.

Technical Specs

Compatible With

• Rockford Fosgate PM300X1 Punch Marine 300W mono amplifier (2-ohm parallel wiring natural pairing)
• Rockford Fosgate TM400X2ad and TM400X4ad Power Marine amplifiers (2-ohm parallel wiring confirm channel power with supplier)
• Sealed, vented, and infinite baffle marine enclosures confirm recommended enclosure volume with Rockford Fosgate documentation before building a sealed or vented box
• Marine vessels: bow riders, ski boats, pontoons, fishing boats, and tinnies with transom or hull subwoofer mounting locations
• Powersport applications: UTVs and side-by-sides with under-seat or roll-cage subwoofer enclosures
• RM112D2 (dual 2-ohm white variant) for 1-ohm stable amplifier pairings
• RM110D4B (10" dual 4-ohm black variant) for applications where 12" diameter is too large
• White finish variant available separately confirm part number with supplier

Frequently Asked Questions

What is the difference between the RM112D4B and RM112D2? Both are 12" Prime marine subwoofers with identical construction, materials, and marine-grade compliance. The RM112D4B has dual 4-ohm coils (2-ohm parallel / 8-ohm series) in a black finish, while the RM112D2 has dual 2-ohm coils (1-ohm parallel / 4-ohm series) in a white finish. Choose the RM112D4B for 2-ohm stable amplifier pairings; choose the RM112D2 for 1-ohm stable pairings.

What impedance does the RM112D4B present to the amplifier? The RM112D4B has dual 4-ohm voice coils. Wired in parallel, it presents a 2-ohm load the standard configuration for pairing with 2-ohm stable mono amplifiers such as the PM300X1. Wired in series, it presents an 8-ohm load. Confirm your amplifier's stable impedance rating before wiring.

Is the RM112D4B a good match for the PM300X1 Punch Marine amplifier? Yes. The PM300X1 delivers 300W RMS at 2 ohms matching the RM112D4B's parallel wiring impedance directly. This makes the PM300X1 and RM112D4B a natural mono amplifier and subwoofer pairing for Punch Marine system builds. Confirm the RM112D4B's power handling with your supplier to verify the match is within the driver's rated capacity.

Can the RM112D4B be installed without a subwoofer box? Yes. The RM112D4B is confirmed compatible with infinite baffle (free-air) installation, allowing direct mounting in vessel transom panels and powersport enclosures without a dedicated subwoofer box. Confirm the recommended free-air parameters with Rockford Fosgate documentation before installing in this configuration.

What is the difference between the RM112D4B and RM110D4B? Both are black dual 4-ohm Prime marine subwoofers with identical construction and 2-ohm parallel wiring. The RM112D4B is a 12" driver delivering more cone area, deeper bass extension, and higher output than the 10" RM110D4B. Choose the RM112D4B when maximum output is the priority and 12" diameter fits; choose the RM110D4B when 10" is the maximum available diameter.