How To Build a Subwoofer Box For Under The Seat

How To Build a Subwoofer Box For Under The Seat?

An under the seat subwoofers offers you a great way to add bass to your car audio system without taking all the space in your car.

As the audiophiles will tell you, housing your under seat sub in an enclosure can help optimize its performance—enabling it to deliver full and deep bass you yearn for.

With that said, you don’t have to spend your cash on buying the box subwoofers out there. Most of these off-shelf enclosure come with exaggerated prices that are just not worth it.

In this guide, you’ll learn how to construct your own subwoofer box design for deep bass from start to finish.

Let’s do this…

What Type of Subwoofer Box Is ideal for Under Seat Sub?

As you might be already aware, there are different types of subwoofer enclosure, with each type producing a distinct type of bass.

How To Build a Subwoofer Box For Under The Seat

How you prefer to experience the low-frequency tones to come out of your car audio system will help you choose the ideal type of enclosure to construct for you under the seat sub.

The THREE most common subwoofer boxes include:

  • Sealed subwoofer enclosure: If you want a deep and precise base, this is the ideal subwoofer enclosure for you. As its name suggests, a sealed box is an airtight enclosure. If you go with this type of enclosure, you should expect a flat response, excellent power handling, and deep bass extension.
  • Ported subwoofer enclosure: if you want forceful bass, then this is the ideal enclosure for you. The ported box features a vent or a port that helps reinforce low bass response. Most car owners prefer this type of enclosure for heavy metal, rock, and any other hard-driving music. Note that a ported box can deliver deeper bass than a sealed box (but it needs to be a bit larger to be able to achieve this).
  • Bandpass subwoofer enclosure: this is a special type of ported subwoofer enclosure designed for people who want maximum slam. In this type of enclosure, the sub gets mounted inside a dual-chambered box—one chamber is sealed and the other is ported—with sound waves emanating from the ported chamber. If you want extra loud sound with a narrow frequency range, this is the perfect enclosure for you.

How To Build A Sub Box for Under The Seat Sub

Now that you know the different types of enclosure available, you need to settle one on that will meet your bass needs.

Build a Subwoofer Box For Under The Seat

For this tutorial, we’ll teach you how to construct a ported subwoofer enclosure as it’s the most popular choice for many car owners.

Things You’ll Need:

  • Speaker wire
  • Carpenter’s glue
  • Wood screws
  • ¾-inch MDF board
  • Mounting screws
  • Tape measure
  • Drill
  • Jigsaw
  • The subwoofer

Follow these steps to build your sub box:

Step 1: Measuring the available under the seat space

The first step involves measuring the amount of space available in your car where you want to install your subwoofer enclosure (that is, under the seat).

Grab your tape measure and obtain get down to measuring the width, depth, and height of the available under the seat space.

Write down these dimensions on a piece of paper so that you don’t forget them when you get down to cutting the box panels in the next step.

Step 2: Measuring your subwoofer.

You’ll also need to measure your subwoofer to ensure you build a box that comfortably houses your sub and enhances its performance.

For this step, we’re assuming you have already bought the best underseat subwoofer for your car.

What exactly to measure in your sub?

Well, first you’ll need to measure its depth (and remember to add about 2-inches to this measurement).

Measure the sub’s frame diameter to help you obtain the minimum height and width of the enclosure.

TIP: Do you want to add any accessories, extra features or designs in your sub box? If yes, be sure to make allowances for these extras when taking the sub measurements.

Step 3: Cutting the box panels

In this step, you’ll need to cut all the MDF panels needed to build the box.

For this step, the measurements you obtained in Step One will come in handy. Using these measurements, cut the front, rear, bottom, and top panels.

Subwoofer Box For Under The Seat

You’ll also need to cut a hole on the front panel using the sub diameter measurement you obtained in Step Two.

Don’t forget to make a port for the cup terminal at one of the end panels…and another one at the other end panel to make this box a ported type (see the video attached in this post). You’ll need the jigsaw and electric drill for this part.

Step 4: Putting the pieces together

Once you have everything cut as per the measurements, you can now go ahead and assemble the pieces together using carpenter’s glue and wood screws.

When you’re done, wipe off any excess glue with a rag and give the glue time to dry. You might consider using a clamp to old your structure together during the drying process.

Step 5: Completing the bodywork

With the glue dried, you can now go ahead and do some bodywork to make your box look good.

Sand the surfaces of the box to make them smooth. knock down any high spots showing on the surfaces so that you end up with a perfectly smooth finish.

Step 6: Testing fitting your new subwoofer enclosure

The final step involves placing your subwoofer inside the new enclosure, making sure that everything fits as expected.

With the speaker in position, mark the areas where you’ll be placing the mounting screws, then remove the speaker and predrill these holes

a Subwoofer Box For Under The Seat

You’ll also need to check if the box itself with fits under the seat where you intend to install it eventually.

Step 7: Painting and making final touches

You can’t leave your box sub like that, unless you don’t care about looks. Give it a paint job to make it look good…you might consider matching your car’s paint color.

Other things you might want to do this is adding any decals, line the bottom panel with carpet to prevent it from scraping your car carpet, adding LED lights, and so on.

Placing your sub box under the seat!

Once everything is set and your new box is ready for use, put the speaker wires through the terminal cup and to your sub.

Place the subwoofer into its new enclosure. And finally put the enclosure in its place, under the seat and use mounting screws to secure it.

Final Verdict

That’s it! You have successfully build a ported subwoofer box from start to finish. If you do everything right, you should end up with a highly functional enclosure that delivers deep and precise bass in your car!

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