15 Inch Subwoofer Box – Volume, Port & Plans
A 15-inch subwoofer delivers serious output and deep bass, but it needs a large box and plenty of trunk space. Here is how to choose the volume and tuning.
Recommended volume
- Sealed box: 50–90 litres net. More accurate bass and easier design, but the box is already large.
- Ported box: 70–120 litres net. This is where a 15″ shows its full potential — much more output from the same power.
With a 15″ driver a difference of ten litres changes the character of the bass, so pick the volume for your specific driver model rather than by diameter alone.
Port tuning and size
Tune 15″ ported boxes to 28–32 Hz for deep, full bass, or 32–36 Hz for more mid-bass punch at the cost of the lowest notes. A port area of 400–700 cm² is typical — for example a 10–14 cm slot about 45 cm tall. Below that the port will chuff at high power.
Example dimensions
A 90–120 litre ported box easily exceeds 900 × 450 × 450 mm outside. Measure the trunk opening, not just the inside — a box that fits inside but cannot pass through the opening is a common mistake. If space is tight, a wedge box or a 12″ driver is the smarter choice.
Plans worldwide, built boxes in Bulgaria
Enter your 15″ driver in the free calculator to get the exact net volume, port length and MDF cut list. Anywhere in the world you can buy the downloadable plan and build the box yourself. Custom-built boxes are made and delivered only within Bulgaria.