Dual 12" Vented Subwoofer Enclosure

4 cu.ft. Subwoofer Enclosure for Dual 12″ Drivers (Digital Plan) – 30Hz Tuning

Build a powerful, high-output bass system with this professionally engineered 4 cubic foot ported subwoofer enclosure design, created specifically for dual 12-inch drivers such as the Sundown Audio X12 or similar high-excursion models. This digital download provides everything you need to build a precision enclosure that delivers deep, clean, and controlled low-frequency performance.

Tuned to 30Hz, this enclosure offers exceptional extension and musical accuracy, making it ideal for daily driving, demo builds, and anyone seeking strong low-end authority. The exterior dimensions come in at 37.75 in (L) x 20.25 in (W) x 17.5 in (H), giving you a powerful box that still fits comfortably in many trunk and cargo areas.

Port & Bracing Details

This enclosure features a high-efficiency L-shaped port system with the following specifications:

• Port Width: 4 inches
• Port Height: 16 inches
• Wood Thickness: 0.75 inch (¾-inch construction throughout)

To ensure stability and reduce turbulence at high air velocities, the port is reinforced with:

• 4 wooden dowels,
• 2 inches in diameter,
• cut to 4 inches in length,
• strategically placed inside the L-shaped vent for superior port bracing

These dowels add structural rigidity to the port walls, helping maintain consistent airflow and reducing port resonance during extreme bass output.

Advanced Internal Bracing

To maximize enclosure strength and acoustic precision, the design includes:

• Full window bracing for panel stability and reduced flex
• Superior port bracing using 2″ dowels
• 45-degree corner bracing to smooth internal airflow and minimize turbulence

This structure keeps the box rigid under heavy load, improves efficiency, and ensures long-term durability—essential for high-powered 12-inch subwoofers.

Digital Plan Includes

• Full dimensional cut sheet for ¾-inch material
• Panel diagrams & assembly layout
• Port specs, length, and tuning data
• Bracing maps for window, port, and 45° corners
• 3D reference views for easy construction

Perfect for DIY builders, professional installers, and bass enthusiasts wanting a high-performance 12-inch enclosure with proven tuning and structural integrity.