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How to Mount Subwoofer in Car Trunk?

If you’re a car driver looking to make sure you have the best possible sound while driving, safely mounting and configuring a subwoofer in your car’s trunk is one of the best ways to achieve that goal.

It will provide an improved bass level and add more richness and depth to common sounds such as radio or streaming audio from your cell phone. Of course, most subs have to be installed in the trunk, but how to do it correctly so they will start moving around? Let’s find out.

To mount the subwoofer in the trunk, use straps or velcro pads. Straps can attach the enclosure to the hooks in the trunk, preventing it from side movements. Velcro pads can be attached to the bottom of the subwoofer, stopping it from moving around. It is also a good idea to build a custom subwoofer to match the trunk size so the box will not move.

As an Amazon Associate, ImproveCarAudio will receive a small commission from qualifying purchases made through the links in this article.

Tip: When looking for a box to match your sub, I recommend checking Skar ready-made enclosures (link to Amazon). They have excellent quality and can accommodate most standard subs.

In this article, I will provide the information you need to be sure your sub stays in place.

Use a Wooden Structure and Metal Plates

One of the best ways to mount a subwoofer in the trunk is by using a wooden structure and metal plates.

This method is best if you want to install a big subwoofer in the trunk, as it will provide the best sound quality and bass response.

Rockford Fosgate Punch P300-12 Single 12" 300-Watt Amplified Subwoofer in Enclosure - Black

You will need to purchase metal plates, which can be found at any home depot, and a piece of wood, which can also be purchased at a home depot. You will also need L-brackets, 1.5-inch screws, and a screwdriver.

Prepare for the Installation

Before starting the installation process, make sure you have all the necessary tools, including screws, a strong rope, hinges, a screwdriver, a wooden structure, bolts, and plastic stripes.

You can also purchase these items at any home depot or online. It’s also important to have a suitable subwoofer box before starting the installation process.

Installation

#1. Measure the size of the sub box and the available space in the trunk of your car.

#2. Use the wooden structure to create a base for the subwoofer box. 

#3. Use the L-brackets and screws to attach the wooden structure to the trunk’s floor.

#4. Attach the metal plates to the sides of the subwoofer box.

#5. Use the bolts to attach the subwoofer box to the wooden structure

#6. Use the plastic stripes to secure the subwoofer box in place.

Secure the Subwoofer in the Trunk Using Velcro

Velcro is the most popular way to secure the subwoofer in the trunk.

It is a straightforward process that requires no additional tools and can be done quickly.

The advantage of using velcro straps is that they are adjustable and reusable, so you can quickly move your subwoofer around or take it out when needed.

Preparation

The Velcro pads are extremely strong and excellent for mounting heavy weights on any surface. It is a plastic latch and hook style rather than the traditional fuzzy and latch hook style.

To apply the Velcro to the subwoofer box, I use an Exacto knife to remove any carpet from the box’s surface. Then, use a heat gun to apply the 3M Velcro. 

The heat will create a tacky adhesion that will securely hold the strap in place.

VELCRO Brand Heavy Duty Fasteners | 4x2 Inch Strips with Adhesive 8 Sets | Holds 10 lbs | Black Industrial Strength Stick On Tape | Indoor or Outdoor Use (VEL-30703-USA)

Before installing the Velcro, measure and mark the sub’s placement on the trunk. This will ensure that the subwoofer is in the correct position and does not interfere with the trunk arms or spare tire.

Alternatively, if you do not want to damage the sub’s finishing carpet, you can secure the pads with small wood screws.

Placement

I recommend placing the subwoofer off to the side of the trunk so that you can still access the ski hatch and spare tire, but for larger subs, this may not be possible, and the heavy ones should be installed in the center.

Also, remember to keep enough clearance on the top so the trunk can be closed, and use the marking pen or pencil to draw lines on the ground to indicate where the Velcro should be placed.

Installation

Using velcro pads is simple and easy and helps keep your sub in place. But keep the velcro strips lined up and pressed down firmly to ensure a secure bond.

#1. First, you need to purchase heavy-duty velcro tape or strips. They are easy to find in Home Depot or online.

#2 Next, clean the trunk and pre-position the subwoofer. I recommend placing heavy subwoofers in the center right behind the rear seats for better weight balance. If you use a smaller sub, you can put it on either side.

When you have a sub in its position, it is handy to mark the corners on the floor so that later you know where to stick velcro pads.

#3. Attach one side of the velcro strip to the bottom of the subwoofer.

It can be difficult to use self-adhesive pads on the carpet, so I secure the strips to the bottom of the sub with small screws all around the bottom part.

#4. Now, take the other side of the velcro strip and attach it to the trunk. 

Make sure that all pads are lined up with the corresponding places on the subwoofer, and for that, use marked lines as per point 2.

Depending on what you have on the trunk floor, you may need to secure the straps to the carpet with some strong glue, or you may need to screw all pads to the trunk floor.

#5. Once both sides of the velcro strips are attached, press down firmly on the subwoofer so it sits tight in its correct position.

Test the Subwoofer

Turn on your car stereo and test the subwoofer to ensure it works properly.

Adjust the settings on the amplifier as needed to achieve the desired bass level.

It’s a good idea to test the subwoofer with different types of music to get a feel for how it sounds and make needed gain and bass boot adjustments on the amplifier.

Mount Custom Subwoofer Enclosure

Of all the different ways to mount a subwoofer in the trunk of your car, the most advanced but also the most effective one is to build a custom subwoofer enclosure.

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This will allow you to get the best sound quality and make the most of the available space in your car. To build a custom subwoofer enclosure, you will need a few items:

  • MDF (medium-density fiberboard) or wood
  • L-brackets
  • 1.5-inch screws
  • saw

When making the custom subwoofer box, there are key steps you need to take:

#1. Define the subwoofer and the size of the trunk.

#2. Cut the MDF or wood to the appropriate size to fit the subwoofer and the trunk space.

#3. Attach the L-brackets to the MDF or wood using the 1.5-inch screws.

#4. When ready, position the subwoofer in the trunk and attach the custom enclosure to the trunk floor using the L-brackets.

I also recommend sealing the enclosure with silicone caulk or another sealant to prevent sound leakage.

This will improve the bass response and overall sound quality. It is also helpful to add some sound-absorbing foam inside the enclosure to further improve the sound quality.

Once the enclosure is built and installed, test the subwoofer again to ensure that the sound quality is to your liking.

With the custom enclosure, you do not have many possibilities to move it around or re-position it in the trunk, so all adjustments must be made in the design stage.

If you need a customized enclosure box for your car to be designed by a professional, I recommend checking CarAudioFabrications, where Mark will be happy to support you. 

Tips for Ensuring the Subwoofer Box Stays Securely in Place

#1. Make sure the subwoofer box is not blocking the rear seats or the back seats of the car

#2. Place the subwoofer box in a position where it will not interfere with the movement of the rear deck or the front seats

#3. Use industrial-strength Velcro to secure the subwoofer box to the trunk carpet

#4. Use wooden plates to keep the subwoofer box from sliding around in the trunk.

Conclusion 

Installing a subwoofer in the trunk is a great way to enhance the overall sound quality of your car, but it’s important to do it properly.

Properly mounting the subwoofer in the trunk will ensure that it stays in place, even during sharp turns or in the event of an accident. It will also provide you with the best sound quality from your subwoofer.

Building a custom subwoofer enclosure can be time-consuming, but it’s worth it for car enthusiasts who want the best sound quality.

It’s also an easy way to make the most of the available space in your car, especially if you have a small compact vehicle or if you are a family person who needs to use the boot space for other things.

Everyone’s car and subwoofer are different, so it’s always a good idea to experiment with different positions and methods to find the perfect fit for your ride.

FAQ

What Common Problems Do People Face When Mounting a Subwoofer in the Trunk?

#1. Sliding of subwoofer box due to not securing it properly

#2. Not having enough space in the trunk for the size of the subwoofer

#3. Interference with the movement of the rear deck or front seats

#4. Damages to the subwoofer or trunk interior

How Can I Prevent My Subwoofer Box From Sliding Around in the Trunk?

One of the best ways to prevent the subwoofer box from sliding around in the trunk is by using wooden plates or plastic stripes to secure it.

You can also use industrial-strength Velcro to secure the subwoofer box to the trunk carpet.

What Is the Best Position for a Subwoofer in the Trunk of a Car?

The best position for your subwoofer in the trunk will depend on the size and shape of your trunk, as well as the size of the subwoofer.

It is recommended to mount smaller subwoofers on one side of the trunk. It’s also a good idea to test different positions, which may affect sound quality.

Is It Necessary to Use a Wooden Structure When Mounting a Subwoofer in the Trunk?

A wooden structure is unnecessary, but it can help provide a base for the subwoofer box and ensure it stays in place. It is used mainly for large, heavy boxes where straps may be too weak.

How Can I Make Sure That the Subwoofer Is Securely Mounted in the Trunk?

To ensure that the subwoofer is securely mounted in the trunk, you should use screws, a strong rope, and hinges to fix it.

Why Is My Subwoofer Not Producing Any Sound?

#1. Make sure that the subwoofer is correctly connected to the amplifier. Check that all cables are securely plugged in.

#2. Ensure that the amplifier or receiver is turned on and set to the correct input.

#3. Check the amplifier or receiver’s volume and bass settings to ensure they are not turned down.

#4. Make sure that the subwoofer is properly mounted and securely attached to the Velcro.

What to Do if the Velcro Is Not Holding the Subwoofer in Place?

#1. Make sure that the Velcro is correctly attached to both the subwoofer and the trunk.

#2. Use the heat gun again to ensure that the Velcro properly adheres to the subwoofer.

#3. Check that the Velcro is not too old. If it is, it might have lost its sticking power, and you may need to replace it.

Can I Use the Rear Seats of My Car to Mount My Subwoofer?

You can use the rear seats of your car to mount your subwoofer. Many car owners sacrifice the rear seats in their vehicles to make room for a subwoofer.

But make sure to mount the sub securely so it does not move around, and remember that not all subwoofers are designed to work in the open air, so do the research before purchasing one.