How To Make / Build A Subwoofer Box

Part of black old car audio subwoofer vintage filtered effect

One of the best ways to personalize your car’s stereo system is to build a subwoofer box yourself. Why should you design and build your own subwoofer box?

  • You can say money.
  • You can cater to your needs and get to enjoy the type of music that you like.
  • You can get better performance for your car’s audio system.

In this article, we will show you steps on how to build a subwoofer box to help you put your personal touch on the sound system of your car.

Building your own subwoofer box can be daunting yet rewarding at the same time. It might take you a couple of days to a week to fully construct one. As long as you follow this procedure, making a subwoofer box will become a fun and easy task.

The most important skills when it comes to building your personal subwoofer box are woodworking skills:

  • Design and build a subwoofer box.
  • Brace the inside of the subwoofer box.
  • Pain, stain, and decorate the subwoofer box.



1. Cubic feet

Before starting to build a subwoofer box, you need to know the minimum and maximum cubic feet enclosure recommended for the subwoofer.

The cubic feet =

1.728 is 1 cubic foot = 12 inch x 12 inches x 12 inches

2. Determine the dimensions of the subwoofer box

  • The front to back dimension is called the depth. The depth of the subwoofer box will be the depth of the subwoofer plus 2 inches.
  • The internal length and height of the subwoofer box will be the length and height measurements of the subwoofer.
  • The internal volume of the subwoofer box will be the product of the height, length, and depth.

Add the thickness of the material to figure out the external dimensions of the subwoofer box.

3. Materials

  • ¾ inch MDF boards
  • Table saw or circular saw (you can also have someone cut them for you according to your measurements)
  • Wood glue or liquid nails
  • ½ inch to 1 ¾ inch sheet metal screws (to make sure the bond is tight)
  • Drill (to screw in the woodscrews)
  • Jigsaw
  • A computer
  • Pencil or pen
  • Tape measure, a large ruler to measure wood
  • Long wood claps
  • Sandpaper (to smooth surfaces)

4. Choose a type of subwoofer box


There are many types for you to choose from. I will introduce to you some of the most common types. You can search for more interesting types using Google.

The type of subwoofer box has to be based on the type of music you want and what size of subwoofer you have in your car’s sound system.

5. Sealed subwoofer box / Acoustic suspension design

This is the simplest and most basic type of subwoofer box.


  • Easy to build.
  • Minor size variations are acceptable.
  • Provides excellent transient response.
  • Provides smooth roll-off and extended low frequency response. The bass coming from it sounds tight.
  • This type of box usually can handle more power.


  • Only suitable with subwoofers that have a long voice coil.

6. Vented subwoofer box

This type of subwoofer box is more complex than the sealed type. The box has a hole in it. This type of subwoofer box has complications of port noise; it is very efficient as it provides great bass response.


  • Allows specialized sound preferred for rock & roll and rap.
  • There are more output capabilities.
  • Reduces distortion and cone excursion.


  • The vent tuning has a resonant effect which makes the sound slightly out of phase so it doesn’t sound as fast as the sealed type.
  • Since the pressure inside the box at frequencies around vent tuning will be a lot higher than in a sealed subwoofer box (can be nearly 2 times), the box needs to be more solidly constructed.
  • It’s more complex to design and build.
  • More sensitive to external changes such as driver fatigue, humidity, and temperature.
  • Midrange sound through the vent can create unpleasant coloration in sound.
  • There might be driver mechanical failure and high distortion due to no movement control below the vent tuning.

Besides the two types of subwoofer above, there are also aperiodic enclosures, band pass enclosures, isobaric enclosures…

7. What shape to determine and the internal volume of that shape

This step is to ensure the correct internal volume for your subwoofer box to get the best sound. I will show you some equations to calculate the internal volume for the most popular shapes.

The first step is to find the area:

  • Circle: Radius2 x π (with π ≈ 3.14)
  • Triangle:
  • Rectangle: Length x width

Then find the volume:

  • Circle: Length x Area
  • Triangle: Depth x Area
  • Rectangle: Depth x Area

8. Choose the material

There are two types of materials you can choose from to build a subwoofer box:

  • Fibreboard (this will be a better choice): Since the material is dense, it can help minimize panel vibrations.
  • Plywood: If you can’t get fibreboard, this can be a good option.

Avoid thin materials since they cause a lot of decompression and compression inside the subwoofer box.

Decide the thickness:

  • 5/8” for volume applications up to 2 cubic feet.
  • ¾” for larger applications.

Don’t use anything less than 1/2” if you plan to build one with Plexiglas.

9. Design the subwoofer box with the WinlSD’s software


You can download the software on WinlSD’s website then install it by following all the installation steps.

For instructions, you can go online and search for some online tutorial. Depending on how flat you expect your frequency response to be. For example, for car subwoofer, tune your box around 25 Hz – 35 Hz.

10. Size the subwoofer box

Now that you have chosen all the dimensions of the subwoofer using WinlSD, it’s time to design the box using all the equations mentioned above. Determine the internal volume of the subwoofer box and the volume that the subwoofer will hold.

You need to brace all the sides of the subwoofer box in order for it to be more solid preventing it from falling apart or rattling.

If you want a port inside the subwoofer box, take into consideration the volume it will take inside it by doubling or tripling is walls.

Cut wood

  • Place the boards on a flat surface in a ventilated and open area.
  • Mark the boards to your planned dimensions.
  • Start cutting the boards on the flat surface following all the measurements and markings. Measure twice, cut one. Remember to not inhale the sawdust.

Make sure you follow all the safety requirements and tips including clothing, gloves, glasses…


Once you’ve done cutting wood, it’s time to assemble all the pieces together, according to your design.

  • Make sure no part is missing in the assembling process.
  • Make sure everything is bonded tightly by clamping them.
  • Make sure the subwoofer box is airtight so you won’t hear high whistling as the subwoofer is playing by using filling materials such as glue to fill any open cracks.


This is the final step to complete the entire process where you can make the subwoofer box look like the one you dream of by using your creative imagination.

To make a smooth surface, sand it with a sand paper. In case you plan to pad under vinyl or use carpet, this step won’t be necessary. Add wood filler to holes.

If you want to see the inside of the subwoofer box, you can place Plexiglas on top of it. You can also give it some cut-outs to make it look cleaner and more stylish. To give it a more of a shiny look, coat and stain it in several layers of liquid glass.

Install accessories

Now, let’s move on to the installation process. The accessories can be insulation, wire, speaker grills, speaker terminals, subwoofer feet…


Now that you’re done installing the accessories, place the subwoofer box to where it’s supposed to be. If it’s too heavy, you might need a helping hand. Before mounting the subwoofer on the enclosure, remember to wire it first.

Once the subwoofer box is in place now, you will have to install the subwoofer. Be careful when you put the subwoofer inside the box so you won’t damage the unit and pinch your fingers.

After that, wire the subwoofer to the main amplifier.

Final thought

You might be wondering, what if you have 2 subwoofers? Should you make one or two separate chambers? The latter would be the best option, even though it’s not necessary. This is because:

  • Bracing: It would be much steadier and sturdier.
  • In case one of them is broken, the volume of the box will be twice as needed. It’ll be a waste of space and affect the sound quality too.

The whole designing and building process can take up a lot of time and effort. You will have to determine many parameters from the start. However, the outcome would be rewarding.

Now that you have everything in control, just have fun and enjoy the music coming out from your personalized subwoofer box.

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