car subwoofer
Car Audio

Quality DIY Car Subwoofer Enclosure – 7 Steps

If you want the deep bass sound in your ride that comes from a kicking subwoofer, you can purchase a sub box from a car audio retailer or buy subwoofer enclosure online. This can obviously become expensive fast when you consider all the components. You can check out many of the components you will need in our guide on car audio and speaker setups.

For a subwoofer to work you will need the following materials:

  • The subwoofer box (or cabinet/enclosure) itself
  • A subwoofer power amplifier
  • Enough speaker cable to reach the sub amp
  • (Optional) mounting brackets to keep it from sliding around

The costs add up fast and it is easy to see that you do not just need the sub box, you also need the other materials. If you are going to have it installed, you also need to pay a technician to wire it up and install it in your vehicle. Of course, you can install it yourself too if you have the time and the skills.

Why You Should Build Your Own Customize Sub Enclosure (Cabinet) Yourself

If you are going to buy a subwoofer cabinet and pay someone to install it, and also purchase all the other components listed above you are already heavily invested in it. Not only have you already spent a handful of cash and spent time finding all the materials, but the store-bought sub enclosures are all made in generic shapes and sizes.

This means there is a particularly good chance the one you buy will not fit perfectly where you need it to go in your car. If you build your own sub cabinet, you will know it is going to be a perfect custom fit and you can finish it with matching material or paint, so it blends right in with your vehicle’s interior.

How Long Should Building A Car Subwoofer Box Take?

This depends heavily on how complex your job is. If you are building a simple cube-shaped subwoofer enclosure box or an easy wedge-shaped cabinet, you should plan on it taking no more than an hour or so. If you are already handy with building things, this will be an easy job and take half an hour or less.

Car Subwoofer Enclosure (Box) Design Plan

1- Planning Your Sub Enclosure Project

This is the most important step. If you do not plan your project correctly, you will end up with a box that does not fit and will not look good. Here are the steps you need to take to come up with a solid plan that will result in a kick-ass result.

Decide on Speaker Size and Quantity

This will be dependent on your amps power output as well as your physical space restrictions in your car. Some have multiple speakers (for example 4×12 or 2×12), while some are just one speaker in the cabinet. Since subwoofers only put out exceptionally low-frequency sound there is really no reason for multiple speakers in the cabinet. One speaker will do the job, but you can add more speakers to increase the volume of your cabinet.

A single 12” speaker is not going to be able to handle too much volume, but a 15” speaker will do the job. If you decide to go with 12” speaker you should consider a 4×12 or 2×12 cabinet design. When you choose your speakers pay attention to the recommended enclosure size from the speaker maker. Once you decide on speaker size and quantity, it is time for the next step of planning!

Measure, and Measure Again

Decide where your cabinet is going to live, then measure the surrounding area with a tape measure. Make sure your measurements are accurate down to the 16th of an inch. Once you have measured the area and written down the numbers, do it again! You should now have a good understanding of how big you need your cabinet enclosure to be and what shape it needs to be cut in.

Sketch it Out

Get a blank piece of paper and draw out how your cabinet will need to look. On your drawing make sure to put the measurements of each dimension. This way when you are cutting the wood you will be confident in your cuts, and the resulting speaker enclosure should match your drawing (or at least be reasonably close).

2- Gather All Your Tools & Materials – Subwoofer Enclosure Checklist

Before you do anything else, you need to make sure you have everything you need in front of you for building your subwoofer enclosure. There are few things more annoying than getting halfway through a project like this and realizing you are missing a part or tool. Do not let this happen to you, get everything you need, and put it all in the same place.

You are going to need:

  • 20-50 bucks (to buy your materials, not including your speaker)
  • Your speaker
  • A speaker terminal cup
  • 6 to 10 feet of speaker wire
  • Enough wood panels for your written plan (3/4” fiberboard is cheap and works well)
  • Panhead screws (sheet metal are best)
  • Jigsaw and table saw (or a rotary saw)
  • 2” drywall screws
  • Silicone caulking
  • Normal carpenter’s glue
  • Electric drill (with hole bits and screw head bits)
  • Non-hardening caulk (also called rope caulk)
  • The finish material for your subwoofer enclosure box (either paint or carpet, etc.)

Now that you have all your project materials in one place you can do the job without worrying you are going to have to stop because something is missing!

3- Build The Sub Enclosure

Take all your plan with the checklist put them to work. Below are the action steps to creating your own subwoofer enclosure then you can style it how you deem fit. You can really make sub box that you will be proud of.

How To Build A DIY Subwoofer Box for Car

diy subwoofer enclosure

Step 1- Cut the Main Pieces

Measure and cut the big main pieces of your cabinet from the wood panels you bought. It is helpful if you can use a good jigsaw blade that is new and sharp. A dull blade will make straight cuts hard to execute.

Step 2- Mark The Speaker Hole

Most speakers will come with cardboard or thick paper template you can use to trace out the diameter of the speaker hole. If yours did not come with a template, you can use a compass to make a perfect circle on the wood that is to become the face of the box.

Step 3- Create The Double Thick Face of Your Cabinet

It is always a good idea to have 2 pieces of wood for the face of the subwoofer enclosure cabinet where you are cutting the speaker hole. This is good for sound and it gives your screws more meat to grab and will secure your speaker much better than a single piece of wood. The subwoofer enclosure cabinet will also be under a lot of pressure from the high-powered amplifier driving your speaker, so double up the wood on the speaker hole section!

Now take your 2 identical pieces of wood and glue them together with a lot of carpenter’s wood glue.

Step 4- Cut Your Speaker Wire Terminal Area Out

On the back of the subwoofer enclosure cut out the shape of your speaker terminal cup. Make sure it is the exact size and shape or you will have a gap that will leak sound and look bad.

Step 5- Finish Up the Raw Wood Box

Now it is time to screw the box together. It is a good idea to pre-drill pilot holes where you know your screws are going, this helps to keep the wood from splitting. Place all the pieces together and screw them into each other. Caulk the seams inside the box.

Step 6- Add Finish Layer

Once the box is constructed and the holes for the speaker and terminals are cut, it is time to finish the surface of the subwoofer box. If you have decided to paint it, apply the paint, and let it dry. If you are finishing with carpet or car interior fabric, attach it now with some glue and let it dry.

Step 7- Install Speaker and Terminal Cup

Now you have an empty sub box that looks great with your finished coat. Line the speaker terminal cup up with the pre-cut hole and screw it in making sure to caulk the back of the speaker terminal cup where it touches the wood.

Take your speaker (or speakers) and lay them in the hole you have cut. With a pencil mark out where the screw holes are and drill pilot holes. Now, screw in your speaker, and you are done!

Make sure to wash your seats and condition them if you made a mess!

Wire up your DIY subwoofer enclosure box and turn on some music!


Making a Car Subwoofer Box Video