Building a Custom Subwoofer Enclosure - What to Know

Custom subwoofer enclosures are for when you want to put some subwoofers into your car but don't want to run stock boxes. By a stock box, I mean one that either comes with your subwoofer or simply one where you can only fit one 12" sub.

If you buy two 12" subs, or perhaps two 10" subs for instance, you'll likely either have to build your own box or get someone to build you one. It's important to remember every subwoofer has an "optimal" subwoofer box size in order to maximize clarity and sound performance. You can check the manufacturer's website of your subwoofer to see what this optimal size is.

You can also skip building the whole optimal performance box in exchange for simply something that will fit into your trunk, but it won't sound as good as if you built one to the specs on the manufacturer's website.
e holes for where the subwoofers go and drill a terminal plate int
Another thing to keep in mind when building your box is to keep all edges perfectly straight. Try to use vice grips to hold the pieces in place before and after gluing, and be sure to place scrues evenly across the construction.

Use a router to machine tho the back to run the subwoofers out the back.

Even if you haven't done the greatest job on your subwoofer box, the MDF wood required to build isn't that expensive. You can always try another one, or use the one you just created. The first few boxes we created here at EuroEnclosures weren't that great either, but you can always tune your deck for less bass output if your box rattles a bit on higher DB output levels.

However, should you want to build the "optimal" box for your subwoofers, be sure to check the manufacturer website of your subwoofers before building.

Building the Best Subwoofer Speaker Box Enclosure For Your Car Or SUV

Box Building

Each type of sub requires it's own type of box. If a sub is installed in a box larger or smaller than what is supposed to, it will sound distorted/bad and could be destroyed. Boxes can be built in many shapes, but it is important that the box volume is calculated accurately to achieve maximum performance.

Materials

A box MUST be very sturdy. Most common building materials are 5/8" or thicker particle board or medium density fiberboard. If building a box with Plexiglas, do not use anything less that 1/2 inch thick. A common material used to mold complex shaped boxes is fiberglass, but it is very hard to work with, and require several layers for a smooth finish.

Gluing, Sealing

Glue should be used at all joints to fill any spaces. Any spaces will degrade the performance of your subs, not to mention the annoying noise air makes when being pushed out of a small hole. On applying the glue, let it cure for at least 24 hours before mounting the subs. This is a precautionary measure to protect the rubbers used to make the subs from the high fumes that some manufacturers glue products have.

Holding Joints Together

In connecting box joints, it is best to screw the joints every four inches or so using 2" - 2-1/2" screws. Pre-drill about 3/4" deep, so that screws do not split the wood at the edges, especially when working with particle/dashboard.

Should I have a Box for Each Sub?

It is advised to have a separate chamber for each sub. Even though not necessary, here are two reasons why such a directive should be taken: First, if one of the subs blows, then the volume of the box will be "twice" as big for the one remaining working sub. This could cause problems and even damage the other sub. The second reason is bracing. Building a box with a divider in the middle will make the box more rigid.

Ports

Ports must be built into your box design to channel out the air made by the sub's vibrations. If a pre-made port is not available, the most common material is PVC. PVC is very rigid, comes in different diameters. Cut the tubing at the desired length. Consider the volume the port takes up when calculating the box volume. Cut a hole in the box. Make sure the hole is as perfect as possible to minimize gaps between the box and the tube. A couple wood braces can be added for screwing the port top the box. Seal the gaps using a proper sealant (Evo Stick or even silicone can be used).

Bracing

Boxes that are more than a foot in width or length or height, should be braced so that the box becomes more sturdy. This can be accomplished with a piece of wood maybe 3 or 4 inches wide across the box). It is a good idea to put wood blocks on the corners for reinforcement. Always consider that blocks, braces, neon lights, etc. inside a box take up space and should be accounted for when calculating internal volume.

Damping/Filling

Damping increases subwoofer efficiency by dissipating some energy that affects the sub, particularly the voice coil. It is advisable to put damping material inside a box. Pillow polyfill and fiberglass insulation are common, though polyfill is a lot easier on your skin. Polyfill also "tricks" a sub into thinking it is in a bigger box. Play around with different amounts of polyfill until you get the desired results.

Making it look professional

Make the box surface free from holes and spaces by adding wood fill. If you decide to paint the box, then you should apply primer first. Carpet or Vinyl padding is the best covering to use since they easily cover any outer blemishes on the box and give the box a 'smooth' outlook. Be careful when cutting the vinyl or carpet since such cutters tend to be very sharp. Cut a piece of carpet (or vinyl) big enough to cover the whole box. Apply adhesive to both box and carpet (EvoStick works great). Wait about a minute and place the fabric over the wood. For the best fit, stretch the fabric when applying it. The fabric should wrap around and end in a place of the box that will not be seen. Do one side at a time, cutting excess carpet. If possible, add staples preferably heavy duty staples that can penetrate the box, to hold the fabric at the ends. NOTE: Do not cover each panel of the box before mounting it together since it would be impossible to find any 'leaks' that may exist in the box design much less fill these leaks.

Building custom front horn cabinets for 18 inch subwoofers. tuned for 45Hz - 800Hz

Designed these enclosers off of a pair of JBL LF horns I have. For anyone that knows the JBL horn sound, such as the classic JBL Paragon, horns bring their own sound to the party and sounds beautiful!! When finished the stereo will consist of 12 X 18 inch Subwoofers, 12 X 12 inch Subwoofers @ 36000watts could end up being more, Ive played around with the idea of 16 X16 @ 46000 watts.

5 Essential 'Must Do's' When Building a Subwoofer Enclosure

Adding a subwoofer to your system is in no way easy, especially if choosing to build a subwoofer enclosure. If you intend to build an enclosure, you will need some essential facts and information before you build it, otherwise something may go wrong, and you could end up wasting your materials.

Must Do 1: Find out what design and size is best for your subwoofer. The wrong design or size could affect the performance of the subwoofer in your car, making your system worse rather than better. The manual should tell you the free amount of air space between woofer and enclosure needed, whilst a simple equation where you find the EBO (efficiency bandwidth products) can help find the best type of design. Alternatively, the manual or a car audio expert may have suggestions on design.

Must Do 2: Decide upon how many enclosures you may need. Although it is not necessary to create two separate enclosures, it practically works better. A sub enclosure can also be separated down the middle in two, so that one sturdy box fits two subs in. If no divider is there though, and one subwoofer malfunctions, it will leave double the amount space needed for the other sub, which will affect the performance of your system. Separating the subs, whether by separate enclosures or a divider (known as twin enclosures), will prevent this from happening. If you have one sub alone, this makes the decision far easier as you will have only one enclosure to build.

Must Do 3: Think long and hard about the materials you are going to use in your enclosure. The enclosure is required to be a hard rigid structure, so that the subwoofer is safely in place and can do its job correctly. Without a rigid structure, the sub can easily be damaged and will not perform as it should. Therefore, the material used needs to be strong and firm, for example, wood, MDF, fibreboard, thick particle board or thick Plexiglas are all used regularly in enclosure structures. Another choice is mould the enclosure into a shape using fiberglass. However, this is time consuming due to the many layers needed.

Must Do 4: After thinking about the material, consider how you are going to make sure it is a fixed and firm structure? Adding braces and strengthening weak points, such as the corners will help keep together your structure. Complete a design on how you are going to strengthen your structure beforehand and remember that any reinforcement or brace will take up air space, which means you'll need to expand the interior space in the enclosure design in accordance with the space lost to the brace.

Must Do 5: When using nails and drills always be careful. You don't want to unnecessarily drill holes or break the structure via screws. The joints are a particular area, which can be easily damaged by screws. Avoid potential damage by distancing your screws out with equal spaces and drilling over half way prior to the screws being placed in, as this will stop the wood from breaking.