How To Build A Subwoofer Box 2023? Top Full Guide

How To Build A Subwoofer Box 2023 Top Full Guide
  • Anthony

In this post, Hooke Audio will guide you How to Build a Subwoofer box. A subwoofer box must be enclosed in soundproofing foam in order to ensure that there are no gaps or holes in the box.

This will prevent the sound waves from escaping outside the box. It is best to use wood when assembling your box, ensuring each piece is glued together tightly. Make sure to cover the insides of the box with soundproofing foam. This foam needs to be thick enough to close up all gaps and will also help with any vibrations that may occur.

Basic Steps To Make a Subwoofer Box

Building a car subwoofer box, you need to consider several factors that will affect its design:

  • Define where in the car you will install the box.
  • Define the shape of the box, whether it will be standard or customized to fit in the vehicle’s body.
  • Define the number of speakers and their size that will determine the volume of the box.
  • Choose the type of box: sealed, vented, or bandpass.

When you have the above information, you need to measure how much space you have in the car, determining any further adjustments to the size.

Make sure you consider the suitable material, which in most cases will be either fiberboard or plywood. Besides, in some subwoofers, you will need a damping material like fiberglass, and if will decide to make a ported box, you will need a plastic port.

How to Calculate Subwoofer Box Size?

How to Calculate Subwoofer Box Size

The most important part of any project is making accurate calculations. It is essential that you put your ideas on paper. This is where you can make any changes and without incurring any costs.

But before you start with the subwoofer box design, make sure you know how much space you have in your car. This is an important step that you should not skip. The last thing you want to do is make a subwoofer box too tall for your trunk by a half-inch.

First, check the volume recommendation of your speaker.

The volume of the speaker type will determine the box’s size. You can adjust the box’s shape and length, but the box volume of your subwoofer box cannot be altered. It is fixed with tight tolerances.

The manufacturer’s manual or the speaker’s paperwork can help you determine the recommended box volume. Here is an example of the specifications for JL car speakers 10W1-4, 10W1-8 subwoofers. Let’s take this as an example and use it for our next steps.

This specification provides basic dimensions for both boxes as well as details about the material thickness. It is 0.75″ or 0.625″, in our case. This is the minimum.

For walls smaller than 0.625 inches, it is best to use thicker wood. This will cause the subwoofer enclosure to be unstable and may start rattling.

Direct factory recommendations will have the best results.

The internal dimensions listed in the specification do not have to be exact. The manufacturer recommends 18’’ x 11’’ x 10.25’’. You can adjust the dimensions to fit your car better, but the volume of the sealed box must not exceed 0.75 cu ft.

To compensate for volume loss, you can either increase the width or height of the box to reduce its depth. You can adjust the size of the box to compensate for speaker size limits.

Here are some examples of combinations for external boxes sizes that you can make up to 0.75ft3 with material 0.75″.

Width – Height – Depth:

  • 18″ – 11″ – 10.25″
  • 17.5″ – 14″ – 8″
  • 12.5″ – 12.5″ – 12.25″

What is the Volume of a Cubic Feet?

Converting cubic feet into inches gives exactly 1728. This constant number is not subject to change. This means that 12” x12″ x12’’ = 1728 cubic inches per cubic foot.

The given box volume in our example is 0.75 cubic feet and 1296 cubic inches.

Remember to use the number 1728 as the starting point when making a subwoofer box.

Let’s say you want to put a subwoofer 10″ in a square box that is as close as possible to the frame’s diameter.

Can The Subwoofer Be Placed In This Box?

Can The Subwoofer Be Placed In This Box

You can see that the mounting hole diameter is 9.125 inches. Therefore, you will need to multiply this value by 2 x the wall thickness.

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9.125″ + 2 x 0.75″ = 10.625″

As you can see, the speaker won’t fit in a 10″ x 10″ enclosure. If this is your limit, this speaker cannot be used in your car. To make things easier, let’s make the smallest box 11”.

How Deep is The 11’x11” Box?

The following formula can be used to calculate the inner depth of your box:

1296 / ((11″ – 0.75″)x (11″ – 0.75″) = 12.33″, this is your inner depth.

You will need to multiply the external box depth by 2 x the wall thickness.

12.33″ + 2 x 0.75 ” = 13.83″s

You can increase depth up to 14″. This will not impact sound quality and will make it easier to do further calculations.

You must also add 2 inches to the depth for the baffle on which you will mount the subwoofer. So in this example, the total box depth is 16″.

For powerful subwoofers mounted in boxes made from thin materials, a baffle or wall with double thickness should only be used on the top of the box.

Once you know the dimensions of your subwoofer box,

11″ (width) x 11″ (height) x 16″ (depth)

Now it is time to calculate all six elements’ actual sizes.

Front and back walls will measure 11” x11”

Side walls require you to subtract the material thickness and adjust accordingly.

2 pcs 11’’ x (16’’ – 0.75’’ – 2.75’’) = 11’’ x 12.5’’

2 pcs (11″- 2 x 0.75″) + (16″- 0.75″- 2.75″) = 9.5″ x 12.5″

This is how you can calculate the proper volume of a sealed container.

You can make a box with custom shapes, or vent with multiple ports. If you are interested in making a box, please create an example project on paper. This will help you to understand the size relationships.

You may also need design software. For the fast design of different subwoofer enclosures, I use WinISD (the link opens in the next window).

To receive a subwoofer box design that fits all dimensions, you will need to fill out the following information: box type, subwoofer driver.

Once you have the correct dimensions for your subwoofer walls, you can transfer them to the material.

Factors to Consider when Designing a Subwoofer Box

Factors to Consider when Designing a Subwoofer Box

You will need to consider the dimensions of the subwoofer enclosure that you are looking for, and where it will be located, especially if it is limited space in your car.

The subwoofer enclosure you are building a box for is another important consideration. What are the minimum depth and maximum enclosure requirements for this subwoofer’s box? Let’s take a closer look at these factors:

The minimum depth of the box

The box’s depth is the distance from the front to back. Add 2 inches to the depth measurement of the subwoofer enclosure to determine the minimum box depth. This is the minimum depth you will need to work with.

Minimum height and width of the box

You can measure the subwoofer’s frame diameter to determine its minimum height and width. Or, refer to the instructions in the manual. If you plan to mount a grille, you will need additional space.

Internal dimensions

Add the double thickness of the wood to the external dimensions to get the internal measurements. In our example, 3/4″ MDF is used. Therefore, you will need to subtract 2×3/4″ from each measurement. These external dimensions can be used to calculate the internal volume in cubic inches.

Available space in your car

We thought it would be helpful to compile some detailed information about how to build a custom subwoofer enclosure.

You can customize your car audio system by learning how to build a subwoofer box design. You will only need a few basic tools and different materials. The hardware is already included.

Cubic Volume = Height x Width x Depth

Since most manufacturers recommend cubic feet, convert what you get to cubic feet. Divide cubic inches by 1728 to achieve this. Make sure that your internal volume is the same as the manufacturers. If it is not, adjust accordingly. After you have made all the adjustments, you can now determine the final dimensions and begin building your box.

What is The Best Material Needed?

What is The Best Material Needed

You must ensure that your subwoofer box design is as rigid as possible, without any flexing when you construct it.

It shouldn’t be an issue with thinner material for small sealed boxes. However, it can pose more problems when you make a vented box or bandpass.

3/4″ or 0.75 inches is the recommended double the thickness for this material. You can use 1/2 inch or 5/6 inches thick wood for smaller subwoofers, such as 6.5″ or 8″. However, I prefer 3/4 inch.

You might be wondering what the best material is for subwoofer boxes. There are many options, so let’s take a look at the most popular.

MDF (Medium Density Fiberboard)

MDF is the most common material used for standard enclosures. This manufactured wood is extremely durable and dense, which helps to improve the sound quality.

It is very easy to cut and assemble, which I find my favorite. MDF is ideal for areas with high humidity and intense winters because it doesn’t warp or expand. MDF is also sound-disruptive because it is thick.

MDF’s one major disadvantage is its weight. It doesn’t matter for smaller boxes unless you have to carry them around every day. But it is critical for multi-driver constructions.

Subwoofers that have 2 or 3 large drivers can weigh more than 200lb. This article contains a weight overview for several types of speakers and boxes.


Another popular material for subwoofer boxes is plywood. Plywood is lighter than MDF and strong enough to not rattle. Make sure plywood is free from any surface defects that could cause vibrations and rattling of the walls.

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Fiberglass is a great choice for lightweight constructions. It can also be used to create complex and customized shapes.

How To Build A Subwoofer Box

How To Build A Subwoofer Box

Once you have your design and all the materials, it’s time to begin making the actual box.

You will need strong glue, sheet metal screws, and caulk to put together a subwoofer box design. I’m using Elmer’s Professional and have had excellent results with MDF. It’s strong and fills in small gaps with an excellent sealing agent.

However, glue is not sufficient. Screws are required to make the box strong. However, sheet metal screws should not be used for too long. Two inches will suffice. I use Hillman fasteners and they work well with all wall thicknesses.

Subwoofer boxes should not be fitted with nails. They will eventually become loose due to vibrations.

You should also place braces between walls. You should also place braces between the walls. They add stability to your box, especially if you have multiple drivers.

Use 2”x2” wood strips to glue between the walls. They are best for large boxes but I use them all the time.

Let’s get started by making the box.

Draw all Subwoofer Walls on MDF

All external measurements should be taken for the MDF box panels. There should be 7 pieces total, 6 walls, and 1 extra panel to mount the driver. Based on our previous calculation, you’ll have:

  • 3 psc – 11’’ x 11’’ – tops and back
  • 2 pcs – 11″ x 12.5″ – side walls
  • 2 pcs – 9.5″x12.5″ – side walls

All pieces can be cut using a table saw

You can cut all panels with a table saw. You don’t need a table saw to make straight cuts. I don’t have a table saw and use this Makita circular saw with a carbide triple blade. It works great with MDF.

All cuts must be square. You will get a lot of dust from cutting MDF. If you’re working outside, it is worth wearing a mask. Make sure to protect your eyes with glasses.

Join Two Front Panels 11” X11” by Gluing

Connecting two 11″ x 11″ panels and double the double thickness will make the front wall of your subwoofer box design.

Cover the entire panel with extremely strong wood glue. The Franklin International 5005 Titebond II Premium Wood Glue has been my favorite and provides a strong connection for larger areas.

Don’t leave any gaps or open edges. This could lead to rattling. Keep the pieces together until dry with a few sheet metal screws.

It is sufficient to leave it outside for at least two hours before I cut the mounting hole.

Mark the center point, and then cut the mounting hole

Once dried, locate a central point on the glued panel. Mark a 9.5″ circle around it. To use your subwoofer’s hole template, you should have one. You can also use a compass to mark if you don’t have a template.

Make a small hole in the center of the circle. You should make sure the hole is large enough to accommodate the standard jigsaw knife. I use a 1/2″ drill to fit the blades.

Make a mounting hole in the doubled panel. A jigsaw is the best tool for this task, and with that, you have the woofer opening.

For a subwoofer terminal, make a small hole in your back panel

You will need to make a hole in your back panel. You will place the subwoofer terminal cup in this hole. It will vary depending on which terminal model you have.

This saves time and allows me to wait for the panels to dry before I mount the terminal cup. Once you have the terminal hole ready, don’t mount it yet. You will cover the box with carpet after you finish covering it.

All panels should be mounted together

It is now time to attach all the panels together. I will start with the back of the box and then move on to the small walls. End result: I cover all walls with a doubled panel front.

Make sure to drill holes near the edges of the panels before you attach the screws to them. MDF tends to split if you screw it too close together.

I am drilling holes with 5/64’s drills. The spacing between each other is 5” to 6″.

Apply a thin coating of glue to all mounting surfaces of the panels

Once you have predrilled all holes, glue all the mounting surface. You should seal all gaps properly. It is better to use more glue than less for the subwoofer box design. After fastening the enclosure, you can remove any excess glue.

Use screws to fasten walls together

Screw the entire box together using pre-drilled holes. For the sidewalls and the back of the box, I use #6×2” or #7×2” screws. However, for the front of my box due to its 1.5″ thickness, I use #3”. This is the most important part of the subwoofer box design. It should not be 2”. MDF requires that the screws used are longer than the others.

This was the last step in building a box. As long as you’re happy with the final result, it was a good job. I will leave the box to dry for a couple of hours after this step. These are the last steps to finish the box.

All gaps between wooden panels should be sealed

After the glue has dried completely, I seal all the internal seals using silicone caulk. This will seal any gaps left in the glue.

I cover all the corners and leave the box to dry completely until the next day. Some silicones can take up to 48 hours to dry. The next step is to carpet the subwoofer box design. This will only be done from the outside.

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How to Use a Carpet Subwoofer Box Design

I use a razor blade, spray adhesive, and a ruler to cover a subwoofer box.

Measure the carpet to determine the right size

Precutting the carpet to the size of the box is the first step.

In this case, I took a piece of carpet measuring 43″ x 70″, and it will cover the entire rectangular box.

The whole carpet can be used, but I don’t like it too big on my table. So I use this formula to calculate how much carpet I actually need.

Carpet width is the front width plus the length sidewalls

11″ + 2×16″ = 43″

Carpet length is the distance from the front to the box’s perimeter, plus one side for overlap.

11″ + 2 x 16″ + 11″ + 16″ = 70″

The carpet should be laid on the enclosure.

Let’s now carpet the box once you have your carpet ready.

It is always better to see carpeting in person, so the content below will show you step-by-step the entire process.

How to Use a Carpet Subwoofer Box Design

Place the wire terminal into the mounting hole

Once you have your box almost finished, it is time to place a subwoofer terminal cup into the hole. To prevent air leakage, I use 1/2-inch screws and silicone caulk from the inside.

Connect the wire terminal to the subwoofer enclosure

Next, connect a subwoofer cable to the connector inside the enclosure. Make sure the terminal is properly sealed against the back wall. It could become the weakest part of the sealed speaker, and ruin the entire project.

You should also remember to keep the wire as short and straight as possible. The wire should not rattle in the box due to vibrations.

Polyfill the enclosure’s interior

I have wire in the box and am filling it with a . I’m not going to fill the entire box, but just the sides and back with spray glue so that the driver can breathe and won’t overheat.

A bass box is filled with enough wire to ensure that the loose wire will not rub against the walls. However, the best thing I noticed was the sound. The bass is deeper because polyfill absorbs sound.

Test it by mounting a subwoofer enclosure inside the enclosure

Once the box has been sealed and connected to the speaker, mount it to the enclosure and test the subwoofer enclosure.

It is worth putting a rubber gasket at the bottom of your speaker before you screw it into the box. This will prevent air from leaking out of the enclosure.

Install a subwoofer enclosure in the mounting hole. Make sure that there is no gasket sticking out. 1-inch drywall screws are used to attach a subwoofer enclosure. Because the double thickness of the front panel is 1.5 inches, it is best to use shorter screws.

Install A Bass Box In Your Car

The radio will turn on when you take the box to your car. Plug a speaker wire into the terminal cup. Don’t increase the internal volume too much at the beginning.

Although you may need to adjust the crossover and amplifier filters to achieve the best results, I’m sure you’ll be happy with the end result if you pay attention to every detail.

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FAQs about building subwoofer box

What is the best wood to make a subwoofer box?

MDF is the most popular and best overall material for subwoofers for several reasons. This engineered wood is very long-lasting. It is solid and thick, which helps bring out the optimum sound quality from your subwoofer enclosure, unlike a thinner board, which allows the sound to reverberate and distort.

What do you build a subwoofer box out of?

Enclosures should be made of the solid, strong wood. Unlike specific particle boards, we prefer MDF (medium density fiberboard) or Medite (high-density fiberboard) or full, weighty, and non-porous. 3/4″ (19mm) MDF is recommended; however, 1/2″ (12.5mm) MDF is okay for woofers 8″ and smaller.

Is a ported box louder than sealed?

If you prefer your music to be “boomy,” rattling the body panels of your automobile, you might consider a ported (vented) enclosure. When constructed with a suitable internal volume and adjusted to the correct frequency for the subwoofer enclosure, these enclosures are often louder than a sealed enclosure.

What kind of subwoofer box is loudest?

Because there is greater space for air to travel inside the structure and expand the sound frequencies, ported boxes may generate a louder sound. If you like a more realistic sound with minimal shaking, a sealed box is an ideal alternative.

Do subwoofer boxes need to be ported?

Ported subwoofer boxes are suggested for customers who wish to improve your complete sound system’s bass, power, and kicking power; ported subwoofers are just what you need to do. Ported boxes are substantially bigger than sealed boxes and have higher power efficiency.

How can I make my car subs hit harder?

You may also make simple changes to your subwoofer enclosure to increase its power. Change the tiny cone in front of the subwoofer enclosure, the voice coil, or obtain a new subwoofer enclosure. If you don’t want to put in much effort, turn off the volume and play your music with medium bass.


Building a subwoofer box is a great way to improve the sound of your car audio system. A well-designed subwoofer box will increase the bass response of your car stereo and improve the overall sound.

There are a few things to keep in mind when designing and building a subwoofer box. Don’t worry. It’s not as difficult as it sounds. You can build a perfect subwoofer box yourself with a few tools and patience.

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