Hertz S300S4 Uno 12" 4-Ohm Subwoofer

The Hertz S300S4 is a 12-inch Uno Series car audio subwoofer designed to add low-frequency output to a properly matched vehicle audio system. Its 4-ohm single-voice-coil design is suited to systems using a compatible mono or multi-channel amplifier. It is a raw subwoofer driver, so it requires a separate enclosure and amplification.

With 250 watts RMS and 1,000 watts peak power handling, the S300S4 is intended for everyday bass reinforcement without requiring an unusually large amplifier. Its 89.5 dB sensitivity supports useful output from moderate-power amplifier systems. The 33 Hz resonant frequency and long-excursion design support low-bass playback when installed in an appropriate enclosure.

This model uses Hertz's V-cone profile with a painted pressed paper pulp cone. The lightweight cone and high-density foam surround are designed to balance sensitivity with controlled excursion. A pure-copper voice coil on an aluminum former supports thermal and mechanical durability during normal operation within its rated power range.

The S300S4 can be used in either a sealed or reflex enclosure, giving installers flexibility to prioritize compactness or greater output around the enclosure tuning range. Hertz publishes a 42-liter sealed-box design and a 50-liter reflex-box design for this driver. These options make it suitable for custom trunk, hatchback, SUV, or other vehicle-specific subwoofer enclosures with adequate mounting depth.

For a complete upgrade, pair the subwoofer with a 4-ohm-stable amplifier, suitable enclosure, wiring hardware, and crossover settings. Hertz suggests a 90 Hz low-pass filter with a 12 dB-per-octave slope for both its sealed and reflex example enclosures. The preassembled ABS gasket provides a finished appearance around the mounting surface after installation.

Key Features

• 12-Inch Woofer: Provides substantial cone area for car-audio bass reproduction.
• 250W RMS Handling: Matches with appropriately rated aftermarket amplification.
• 4-Ohm SVC Design: Supports straightforward amplifier load matching.
• V-Cone Paper Cone: Uses a lightweight, stiff cone profile.
• High-Density Foam Surround: Supports cone travel for low-frequency output.
• Sealed Or Reflex Ready: Works with Hertz-published enclosure options.

Design & Installation

The S300S4 combines a painted pressed paper pulp cone, high-density foam surround, high-density-flux ferrite magnet, and pure-copper voice coil wound on an aluminum former. Its motor structure uses low-carbon-content steel, and the driver has a preassembled ABS mounting gasket. The driver weighs 3 kg (6.61 lb) and has a listed overall diameter of 307 mm (12.09 inches).

Plan for a 279 mm (10.98-inch) mounting hole when following Hertz's published enclosure designs, and verify available depth before cutting a custom panel. Use a rigid, sealed enclosure or a correctly built reflex enclosure sized for the driver rather than free-air mounting. Set the amplifier and low-pass crossover conservatively, confirm polarity, and match amplifier output to the subwoofer's 250-watt continuous rating at a 4-ohm load.