Hertz MPS 300 S4 12" Shallow-Mount Subwoofer

The Hertz MPS 300 S4 is a 12-inch shallow-mount car subwoofer designed for systems where conventional deep subwoofer enclosures will not fit. Its 88 mm mounting depth helps make it suitable for compact custom installations, including under-seat or rear-bench enclosure applications. This model uses a single 4-ohm voice coil and is intended for dedicated low-frequency reproduction.

With 500 watts continuous power handling and 1,000 watts peak power handling, the MPS 300 S4 is built for use with an appropriately matched mono or bridged amplifier. Its 25-400 Hz frequency-response specification supports integration with a full-range speaker system through an active crossover. Hertz specifies a 22.7 L sealed enclosure as a compact recommended alignment.

The polypropylene cone and high-density flux ferrite motor are paired with a six-layer copper voice coil for thermal capacity. Hertz uses a dedicated spider and voice-coil support arrangement to place the magnetic assembly farther inward. This layout reduces mounting depth while retaining substantial cone travel.

Hertz Air Intercooling Revolution (A.I.R.) technology is designed to manage airflow within the voice-coil inner chamber and magnetic assembly. The design is intended to reduce air-compression effects while improving cooling around the motor structure. The subwoofer has a specified Xmax of 16.8 mm and a maximum mechanical excursion of 20 mm.

The MPS 300 S4 is a practical choice for a space-conscious bass upgrade that still uses a full-size 12-inch driver. It can be installed in a sealed enclosure for compact, damped bass response or in a properly designed reflex enclosure when installation space permits. A grille is provided to help protect the driver in exposed cabin or cargo-area installations.

Key Features

• Ultra-Shallow Depth: The 88 mm mounting depth supports installations with limited enclosure clearance.
• 500W Continuous Handling: Supports amplifier matching for substantial low-frequency output.
• Single 4-Ohm Voice Coil: Simplifies wiring to a compatible 4-ohm amplifier load.
• A.I.R. Technology: Optimizes internal airflow around the voice coil and magnetic assembly.
• Six-Layer Copper Voice Coil: Provides thermal capacity for sustained powered operation.
• Included Metal Grille: Helps protect the cone while maintaining a clean installed appearance.

Design & Installation

The MPS 300 S4 uses a polypropylene cone, high-density flux ferrite magnet, die-cast aluminum frame, and non-vented rear structure. Its supplied grille combines a cast aluminum ring with black steel mesh, while the mounting hardware is designed to remain visually discreet after installation. Solid horizontal spring-loaded terminals are specified for 8 AWG cable.

Install the subwoofer in a rigid enclosure with the correct 283 mm mounting hole and adequate rear clearance. Hertz specifies a 22.7 L sealed enclosure as its compact recommendation, with suggested sealed-system filtering of 15 Hz subsonic at 24 dB/octave and 70-80 Hz low-pass at 24 dB/octave. Use an amplifier and wiring arrangement appropriate for the subwoofer's single 4-ohm impedance and 500-watt continuous power rating.