The Killerado features a kerfed, ported high performance enclosure with two 15" HDC4 subwoofers.

High Performance Enclosure

Tiny subs in tiny boxes give you a sound that’s…well, tiny. If you are looking for real bass, you need a real box. In this post, you’ll learn about how to create a high performance enclosure.


In order to get true high performance, you have to make sure the woofers have enough air to “breathe.” The more air you make available, the higher the potential SPL. In each SoundQubed subwoofer series, the parts are mostly the same. This means the HDS2.115 has the same amount of throw and force available as the HDS2.112. The smaller sub in the right space will outperform the larger sub in too small of an airspace.

The first step in getting major bass in your vehicle is to allocate the space for your enclosure. If you really want to flex some sheet metal, the old adage applies, “there is no substitute for cubic inches.”

You don’t have to use a large amount of enclosure space to make a loud system. With a box built for high performance, loud can be done with a single subwoofer in the right enclosure. The amount of loud needs to be determined as you figure out what space you plan to give up. Really loud bass, where you have to scream at your passengers, can be done on a single or double woofer setup. Stupid loud bass, where there is no point in trying to communicate in the vehicle, takes more space and bigger/more subs. F@#$ing crazy loud bass, where it is impossible for the car next to you to communicate inside his vehicle, takes even more space, even more subs and a gazillion watts of power.

Box Shape

If you squeeze a giant box into your trunk, it will be extremely loud. Unfortunately, all you’ll hear is the box rattling. For a rear-firing box in your trunk, make sure it doesn’t seal off the trunk from the passenger compartment. You need to leave space for the sound waves to pass back into the interior of the car. One method is to make the box as low profile as possible. The waves can then pass over the box and enter the cabin via the seat back and rear deck. You could also reduce the width of the box so the waves can pass around the sides and into the cabin.

If you have a hatchback car, keep the box as far back in the vehicle as possible. Also keep the port as far to the rear as possible.

Box Construction

A strong box is essential in a high output system. Your box should be free from air leaks and braced internally if the volume exceeds 2 cuft. Internal cross bracing is far more effective in making a rigid box than doubling the wood thickness. Doubling the wood thickness adds a great deal of weight to your vehicle. Also, the added wall stiffness is less than stiffness added by cross bracing. Try to cross the braces at the same point so that they add strength to each other.

If your cuts are messy, the inside seams of the enclosure can leak air and create weakness in the box’s structure. One way to strengthen these joints is to use gluing cleats on the inside seams. Stronger, more air tight construction are crucial to a high performance enclosure.

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Comments (8)

  • Author has kept superb unknown ideas, that will help most of music lover. It is not only includes huge ideas but also user friendly with figure-out post. If anybody read this article will reinforce to get this. Thanks a million for this post.

  • 9.0cu ft box currently in my 98 yukon thats including port volume, 16sqin of port area per cu ft. Of box volume. Problem is my hdc4.18 flexes the 3/4inch mdf like ive never seen, can u please show pictures of an example of an ideal braced box, siliconed and woodglued all seams inside box and 3inch screws are placed every inch apart. Do you recommend rounding the outside entrace to the port aswell?

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