Placing Subwoofer in a Car (Complete Guide)

Adding a subwoofer to your car’s audio system can help you get the best sound quality, especially the heavy boom-bass effect in your favorite music notes.

Additionally, if you prefer bass tubes over box enclosures, it can be a space-saving option and the most affordable way to enhance the overall music quality.

Similar to subwoofers mounted in box enclosures, bass tubes are capable of handling the lower frequencies in musical notes.

These compact units can easily reproduce the boom-bass when integrated with your car’s audio system.

The best part is the built-in amplifier in bass tubes makes your installation job more easy.

Let us go through the installation steps of subwoofers in your car along with the best placement options.

The most common placement option for a subwoofer typically sits in the trunk of the car.

That being said, it’s highly recommended to get the wiring tasks completed by a professional to be on the safer side.

If you still want to do it yourself, be very cautious in performing the steps.

Where Should you install the subwoofer in your car?

It’s best to install the subwoofer in the trunk of the car, ideally in the center facing the rear. This location balances the bass distribution inside the vehicle, enhancing the audio experience. Ensure secure installation to prevent movement and potential damage.

While installation make sure that the subwoofer is installed in a ventilated space in your car.

Here are the common and ideal places to install the subwoofer in your car.

Best places to install a subwoofer in your car

best places to install subwoofer in a car

Music lovers can find out numerous ways to fix audio systems even in their cars with compact spaces.

Installing a subwoofer in different spaces will also depend on the type and especially the size of the subwoofer.

The most common areas to place a subwoofer in a car are listed below:

  • Trunk
  • Dashboard (car’s front)
  • Under the seat (Rear and front both)
  • Car’s door

Placing the subwoofer in the Car’s Trunk

placing subwoofer in car trunk

To get the best sound output and save some space you should install the subwoofer in the trunk of your car.

The trunk area will allow more room for the subwoofer to utilize the surrounding air freely and output deeper bass in your car all around.

It is an ideal space to place a subwoofer of a marginally bigger size. This is because the trunk area in a car is typically spacious, especially in the Sedan and SUV categories.

Also, the space in the trunk of a car is not always entirely utilized and even if you do it is quite rare. Hence, it becomes the best placement option for the subwoofer.

Additionally, when a sub is placed at the back, it will allow more legroom for the passengers to sit comfortably in the car.

Moreover, proper mounting can also keep it safe in the trunk from being punctured with sharp objects that can come in contact with it.

All you need to keep in mind is to prevent the subwoofer from heavy luggage items such as gym equipment or any hard or sharp object while using the space in the trunk.

In some cases, the installation can be challenging and tedious if the car is too compact with less space in the trunk area.

Placing the Subwoofer Under the Car’s Seat

Placing a subwoofer under your car’s seat can be applicable to both front and rear seats.

However, under-seat subwoofers may not be able to output high-level bass notes in your car but can be used as a placement option.

You can place about 6 inches to 8 inches (size) subwoofer under the front seats, additionally, you can prefer installing two subwoofer units for better bass output.

On the other hand, installing a subwoofer under the rear seats can result in an even sound distribution and experience better bass effects in your car.

It is challenging at times to install subwoofers in the rear seat but can be a better option than the front seats.

For even sound distribution you can place the subwoofer facing the front seat or to the ground.

If you prefer installing them under the rear seat make sure to use the best settings for different music notes.

This is because the sound may be too loud for the ones sitting in the rear seats as they will be closer to the installed units.

Placing the Subwoofer at the car’s front or Dashboard

Small and compact subwoofers can be installed at the front of the car’s cabin which is near the dashboard. This is typically a choice of motorists who love to enjoy a more smooth and precise bass output in their favorite music notes.

However, the ones sitting in the rear seats may not be able to enjoy the same sound quality and you will need an additional subwoofer setup somewhere at the back.

The installation of subwoofers at the front car cabin also helps minimize the task of running lengthy wires throughout the car.

Placing the Subwoofer on the car’s door panel

Installation of smaller-sized subwoofers on the panel of your car’s door will act as a supporting unit from the sides.

The fact is that you will not be able to fix subwoofers more than 2 to 4 inches in size on the door.

Even the best professional technicians don’t suggest adding subwoofers to the door of a car because the setup can be more complex.

Above are some of the best subwoofer placement options in the car to enjoy great sound quality on every ride.

The placement of subwoofers may vary according to the type of car such as SUV, sedan, or hatchback.

Choose the right Subwoofer for your car

It is always best to finalize the best subwoofer that will suit your car’s audio system and meet the installation requirements.

Let us answer your question below.

Which subwoofer is best for your car?

Subwoofers are typically categorized by active and passive units. 

Active subwoofers are also referred to as powered subwoofers and are quite popular in-car audio systems. These units are not dependent on the power output of a separate or external amplifier.

Active subs have a built-in amplifier that automatically adjusts with the frequency responses of the speaker and the audio system to deliver the optimal sound quality.

Additionally, active subs are less expensive and can help you save space in compact cars by eliminating the need for an additional amp.

On the other hand, passive subwoofers need to be powered with the help of an external amplifier.

It will add to the overall cost with the inclusion of an amp and setup requirements. Moreover, you will have to sacrifice some space in your car.

It is also right that passive subwoofers can deliver better bass output, however, an active sub should be more than enough for smaller spaces such as for cars.

You can also consider installing a bass tube which is gaining more popularity in car audio systems. Bass tubes are a form of active subwoofers available in a tube-like (cylindrical) shape.

Bass tubes include built-in amplifiers and eliminate the need to install external amps. This means you don’t need to worry about losing additional space for the amp and complicating the setup.

These units are designed more compact than traditional subwoofers that are typically mounted in box enclosures.

You should always explore your options when it comes to size and considering the placement options.

Once you have chosen the right subwoofer and placement spot you are all set to proceed with the subwoofer’s installation process in your car.

Steps for installing subwoofer in a car

Before installing a subwoofer in your car you should keep a few things in mind.

Things to remember:

  • Always disconnect the car’s battery while working on electrical units.
  • To prevent electrical shocks (discharges) you should connect a ground wire to a metal bolt on the car.
  • Keep the audio system (electrical) kit handy. It will include all the equipment needed to wire a subwoofer in your car and is available online or at local stores.
  • Finally, make sure to choose a well-ventilated space in your car, especially for the subwoofer’s placement.
  • If you are installing a passive subwoofer make sure to install the amplifier close to it.
  • An active subwoofer with a built-in amp can ease the installation task.

Things that you may need for the setup

  • A subwoofer or a bass tube
  • Amplifier (applicable for passive subwoofers)
  • Electrical wire for Power.
  • Ground wire
  • RCA jacks and cables or with connectors (Red and White connectors)
  • Remote wire (blue)
  • Speaker wires (as per requirements)
  • Wire cutters and strippers
  • A wiring kit and basic hardware tools
  • Electrical Tape
  • Fuse line and holder (50 amps to 60 amps or higher)
  • Terminals to connect wires (crimp ring terminals)
  • A dedicated space as per the type and size of the subwoofer

Note: The items listed below will vary according to your car’s audio setup requirement. Also, make sure to use the right length of wires and suitable electrical fittings.

Step 1: Disconnect the car’s battery

disconnect the cars battery

Remove the terminals (red wire) from the car’s battery to prevent any damage to the battery or the audio system.

This will make sure the battery is disconnected and nothing goes wrong from the electrical point of view.

Step 2: Arrange wiring for power

From the wiring kit pick the red positive wire and run it from the car battery that is typically located at the front.

You should use the appropriate wire length and avoid any alteration or joints. 

Simply put, the wire should be of sufficient length to reach the car’s trunk from the front of the car (battery).

Step 3: Routing the power wire to the battery

You will need to run the wire from the battery into the dashboard before running it to the trunk of your car.

The most challenging step is to get the wires to the battery, however, you will be able to spot existing gaps or holes (plugs).

The existing gaps or holes may have wires that are already being fed and can make your job easy.

By doing this you can avoid additional drilling for holes and finding another right-size rubber grommet.

Additionally, you can make a hole in the rubber wiring harness seal (grommet) by pushing a screwdriver or similar tool through it.

Typically there’s a plastic filler plug or a rubber seal with a factory wiring harness in the dashboard that goes into the engine.

Try pushing it out to gain access to a free hole that can be used to push the wires through.

If you don’t find a plastic tube dedicated to adding wires or if there isn’t any space to push the wires through then you can make a hole through the firewall from the dashboard area.

Do this step only if it is applicable in your case so that you can make a way to push the amp wire through it.

Once the wires are through leave it close to the battery and DO NOT make any connections to the battery at this point.

Note: A firewall is a panel or a frame between the engine compartment and the cabin of a car.

Step 4: Running the power wire to the subwoofer

Finally, one end of the cable from your car cabin has reached the battery, let’s take the other end towards the spot chosen for the subwoofer.

Depending on the chosen spot route the wire accordingly such as from under the carpets, between the doors, and seat whichever is applicable.

For instance, if you’ve chosen the trunk of your car then the wire needs to run to the back.

This particular step will require you to access the areas (floor) below the carpet and the glove box compartment.

By doing this you can have a better look at the available resources and wiring spaces.

In most cases, you can whip off the available plastic trims to tuck the wire beneath the carpet, however, usually there are looms that already exist in cars for wiring purposes.

Once the power wire reaches the subwoofer you are more than halfway done.

Subwoofers installed under the seat, near the dashboard, door panels, etc., may include similar or different routes to run the power and RCA wires.

Step 5: Route the RCA cables from the Subwoofer to the stereo

Now, you will need to route the RCA cables (Red and white color) and the Remote wire (Blue color) from the car’s trunk to the stereo.

Make sure to choose a different path or the opposite side of the car to run RCA cables which should be away from the routed power cable.

If you run the power cable and RCA cables together they may interfere and can affect the sound quality.

You can also check your car’s wiring graph to find any existing wiring present in your car to plug into the speakers and subwoofers and the stereo to the trunk.

Once you have routed and connected the RCA cables to the Subwoofer, it’s time to connect them to the stereo.

Note: The blue remote cable is required to signal the amp if applicable.

Step 6: Connect the cables to the stereo

connect car cables to stereo

Pull out the stereo head unit to find the available slots for RCA cables. The stereo head unit is usually clipped to its assembly or enclosure through plastic clips.

Simply pry out a few clips from the dashboard panel using a flathead screwdriver.

Some car models may require unscrewing the stereo frame from the dashboard panel.

Now, gently slide the stereo out to access the available plugin slots which can be either available at the side or at the back of the unit.

Plug the RCA cables carefully according to their respective colors red and white. In some stereo units, you might find multiple red and white colored slots.

If you find slots labeled as R/SW (‘R’ stands for Rear), use them to plug the RCA cables as it is typically available to manage audio in the rear of your car.

RCA cable and ports

Finally, if you are connecting a passive subwoofer with an external amp you will need to connect the Blue remote wire to the stereo.

Most modern active subwoofers and amplifiers do not need a dedicated remote (blue) wire.

This is because these subs and amps work with signal-sensing technology. As soon as a music signal is released the unit will automatically power up the system.

On the other hand, in standard audio systems, a blue REM wire does the job of passing on the signal to the amp from the stereo.

If your sub is paired with an amp you will find a slot on the stereo labeled as REM, Remote, Antenna, or Amplifier (Here you can connect the blue wire).

In some cases, there will be a blue wire left loose from the stereo that can be joined together. You can either crimp them or solder them and wrap them with electrical tape.

Now, tuck the wires to the back of the stereo and push the stereo back to its enclosure.

You are done connecting the subwoofer to the car’s stereo.

Step 7: Grounding the black wire

One of the most important steps is to secure the ground wire to exposed metal to route excess electricity away from the audio system.

You can connect one end of the ground wire to the nearest metal bolt fastened to the body of the car such as the chassis.

Most manufacturers include a common ground connection to ‘earth’ various electrical components and it can be in the form of a bolt fastened to the chassis of your car.

If you are not able to locate the grounding contact point, simply install one. You can choose a (unpainted) metal part for drilling with the help of a masonry bit.

Next, insert a metal screw or bolt and fasten the grounding wire. Make sure to insulate the wire using a wire stripper before securing it to the metal bolt.

Finally, attach the ground wire to the amp to direct excess power away from it.

Step 8: Connect the fuse and power cable to the battery

With all the other wirings in place, you can now connect the wires to your car’s battery.

You can use a crimp ring terminal to attach the positive (+) wire to the battery clamp. It can be a stud or bolt.

But you will first need to connect the fuse to the wire at least 12″ away from the positive terminal point.

To assemble the fuse holder, trim about at least half an inch (1/2″) of wire to fix it onto the exposed positive wire. You can use a crimp tool or pliers to crimp the fuse holder to the wire.

Once the fuse is installed, place the holder close to the battery’s terminal with approx 12″ or less of wire length.

Put simply, the fuse should be connected to the wire at least 6 inches to 12 inches away from the battery’s positive terminal.

This is applicable as a general rule to prevent battery explosions or fire hazards that can happen without the installation of a fuse.

The shorter length of the wire between the fuse and the battery terminal (6 to 12 inches) is to make sure that there’s not enough wire to be in a short circuit range.

Secure the fuse using zip ties with the nearby wirings or brackets and close to the battery’s terminal.

Finally, connect the loop terminal from the red wire with the (+) terminal on the car battery.

Step 9: Connect the power cable to the amplifier

Connect the red power cable to the amplifier’s slot labeled as “Power”, however, it can also be labeled as “Battery” or “12v”.

You will need to strip small insulation of about half an inch (1/2″) of the wire’s end.

Next, squeeze the insulated threads of wire together so that it becomes easy to insert or push it into the power slot of the amp.

To ensure a firm fit some slots are controlled by small screws or a pull-back clip. Accordingly, loosen it to insert the wire and then secure it firmly.

Note: If you’re installing an active subwoofer, the wiring slots can be located on the back of the subwoofer.

Step 10: Connecting the battery’s negative terminal wire

Finally, we have reached the point of connecting the last piece of wire which is to the negative terminal of the battery.

Remove the nut from the negative (-) terminal of the batter to hook the negative cable and secure it back with the nut.

You will need a wrench or socket wrench to loosen and tighten the nut.

Inspect the wirings for any faulty connection and also check if the wires and cables are secure and firmly connected to the right slots.

If at all things look good to you, simply start your car and turn up the stereo to test the sound quality.

Final Thoughts

Choosing the right subwoofer type and setting it at the right spot can help enhance the music of your car stereo system.

The placement and type of subwoofers may vary according to your car, because, the bass effect and acoustics will vary in the cabin of a hatchback, sedan, and SUV.

If you are unsure about the choice of subwoofer and placement options, it is best to consult a professional technician.

Finally, it is also best to get the required wiring done by a professional before connecting the subwoofer to the car’s audio system.

Armed with a Diploma in electrical engineering and a remarkable 12 years of expertise, he excels in rejuvenating music systems, washing machines, dryers, and laundry-related appliances. Manish's profound insights and practical know-how establish him as a credible authority in appliance and music system repairs. Contact: manish.singh (at) subwooferblog.com. He's always ready to lend a helping hand!