Installing A Car Subwoofer : An easy to follow guide

Adding a subwoofer to an existing factory stereo or as part of a complete new sound system is a very worthwhile mission. You will get a cleaner, deeper more powerful sound and if connected to mids and tweeters will give you an amazing full range of sound. The difference between the quality of the sound even with low volume will be easy to hear. Installing a car subwoofer correctly will add rich, deep bass sounds and vibrations creating an amazing audio experience.

However, installing a subwoofer can be a steep learning curve if you have never done it before. This is why I thought it would be a good idea to write a simple guide that can help you fit your own. 

How Much Does It Cost To Install a Subwoofer?

There are different components that you’ll need to install a subwoofer, but the main costs are the car amplifier and the subwoofer. If you choose to build a box to house the sub or buy the subwoofer already housed in a box- is completely up to you. Although if the thought of building a box puts you off – you can buy pre made boxes which are perfectly good to use. When you add up the cost of all of these components, as well as the installation process itself, the price can range anywhere from $100 to $600. The main costs are the subwoofer and the amp though.

What Materials And Equipment Do I Need?

To install a car subwoofer system, you will need the equipment and materials listed below:

  • Subwoofer box
  • Subwoofer speaker
  • Amplifier
  • Wiring kit that includes:
  • 20-foot 10 Gauge or thicker insulated wire for power
  • 3-foot 10 Gauge or thicker insulated wire for the ground
  • 15-foot 18 or 16 Gauge wire
  • 15 feet or longer RCA cables (one with both white and red or two different ones)
  • 50 amps or a higher in-line fuse
  • Speaker wire
  • Four small wood screws
  • Basic tools

You have to make sure you get thicker wires for the ground and power wires. This mostly depends on the power of the amplifier; if you have a really powerful amplifier, you may even need to go as far as 0 gauge wires.

Pro tip: you can get amplifier kits at your local stores like Walmart. You will be able to check the watts they can handle on the kit too. This seemed easier to me than going and buying wires separately.

How Do You Hook Up a Subwoofer?

Once you have your subwoofer, equipment, and materials, you can easily hook up the subwoofer to your car’s stereo system. I have broken down the process in some simple steps below.

Disconnect the Battery

The first thing you need to do is shut off the car and pop the hood open. The battery looks like a rectangle box with black and red cables connected to some metal prongs on the top. The cables are attached to the battery with a pair of nuts. You can pull out the cables by turning the nuts clockwise with a socket wrench or regular wrench.

Running the Wires

You have to start wiring the power from the battery instead of the fuse box for the subwoofer. The fuse box has “unclean” power that may result in noise from the engine being amplified through the speaker system. You may even end up blowing a fuse if you wire the subwoofer with the little ones on the fuse box.

The first thing you should do is find an opening the firewall of the car where the wires can go through. The firewall is the metal wall close to the windshield under the hood of the car. I think the best place is the hole behind the glove box since it can be fairly easy to reach from the engine’s compartment.

Weave the power cable through the hole in the firewall, but make sure enough of it is left to reach the battery. At the end of the wire, you will need to strip off the insulation. The in-line fuse will wire with the stripped end, as close to the battery as possible. Do make sure to tape the place carefully where the wire is fused so that you don’t end up with a short.

The remaining should run through a wire channel or under the carpeting until it reaches the subwoofer. While the carpeting is loose, you can also run the RCA cables and 16-18 gauge wires between the subwoofer and the stereo.

Wiring the Audio System

The stereo head unit needs to be taken out. This requires you to take off the entire front end of the center console. Once the stereo is out, take a look at the backside. You should be able to see 2 RCA connections that you can connect the RCA cables to. If you don’t see these connections, you will have to spend some time splicing the wires with the rear wires of the speaker. For me, the better option was just to go buy a new stereo that has RCA options since they aren’t that expensive anymore.

Wiring the Remote

The 16-18 gauge wire runs through the back of the console. This wire is the main component that will turn on the amplifier when the stereo is on as well. You will also be able to spot the remote wires coming out of the back of the unit. They are blue wires that may be labeled as any of the following:

  • Remote
  • Rem
  • Amp
  • Amplifier
  • Pwr. Ant.
  • Power Antenna
  • Antenna

Or probably something along those lines.

If there are two blue wires, one should be labeled as Amplifier or Amp. You can use this connection spot even if there is only one blue wire. If you have the power antenna option, then you will have to splice the blue wire too. When you connect the right blue wire to the 16-18 gauge wire, the amp will come on when the stereo does.

If you don’t see a blue wire or power antenna, it might be a stock stereo. In this case, you will have to run the 16-18 gauge wires directly to the fuse box. In this case, your amp will always come on when the car is on, but it won’t make a lot of noise. The engine sound was coming through mine, so I added a switch for the amp that I use to turn the amplifier on or off.

Putting the Speaker in the Box

Make sure the thin gasket thing is on before putting the speaker into the box. Connect any connectors on the outside of the box to the speaker inside. The holes on the outside of the speaker’s rim can be used to screw the speaker into the box.

Wiring Up the Amp

Now that most of the wires are in place, you can wire up the amp now. You have to connect the power cable to any of the following spots on the amplifier:

  • B+
  • Batt.
  • Pos.
  • +12v
  • 12v
  • Power
  • Pwr

Do make sure not to connect it to the speaker positive. The 16-18 gauge wires will be connected to the following:

  • Remote
  • Rem.
  • Ant.

The ten gauge 3-foot wire will be connected to the following:

  • B-
  • Neg
  • -12v
  • Ground
  • Gnd

Do make sure not to connect it to the speaker negative.

Now, you have to connect the ground wire’s other end to the bolt that is connected to the body of the car. You should connect the speaker’s wires to the speakers on the amplifier at the + and – places. If there are two channels, you will need to bridge the amp. Bridging is a pretty easy process, and you will be able to find how to do it on Google (that’s how I learn practically everything!)

The speaker wire on the other end will be connected to the – and + on the speaker box. One thing you should keep in mind is that the + on the speaker should be connected to the + on the amp, and the – on the speaker should be connected to the – on the amplifier.

Adding Power

The last step that you have to do is connect the power cable to the battery. I just tend to shove the wire directly between the post and the battery clip on the batter.

And there you have it! That is how you install the subwoofer system!

Where Is the Best Place to Put a Subwoofer?

Without a doubt, the trunk is the most popular place for the subwoofer. Since they tend to be heavy and big, the trunk is the perfect place to house the subwoofer.

Should a Subwoofer Be On the Floor?

Car subwoofers are usually heavy, clunky, and big. You probably won’t have much choice when it comes to their placement since they will eventually end up on the floor. However, the sound can get thin or boomy, depending on where you put it. This has to do with the room interface and the basic output of the subwoofer. You may have to experiment a little with the location to get the most out of your subwoofer.

Do You Need an Amp for a Sub?

If you want a subwoofer in your car, you will definitely need an amplifier. There are some articles I’ve come across that show people how to install the subwoofer without an amplifier. I tried out the subwoofer system with and without the amplifier, but honestly, after putting in so much effort to install the subwoofer, the subpar quality of the sound without the amp bummed me out.

If you don’t have the right hardware or a great car audio system already, the amplifier is more important than you may think. Personally, the amplifier system seems a given to me, but everyone wants something different out of their sound system. There are no wrong answers here, so you can do what you like!

How Do I Choose an Amp for My Subs?

When I went to buy my amplifier system for the subwoofer, I was only looking at the peak power values. My friend, who was with me at the time, pointed out the mistake I was making. The amp or the speaker can only run at peak power for around a minute before it starts to overheat or goes bad. When you are playing something, you usually run the subwoofer on the RMS rating since that ensures the best sound quality. No one really runs the amplifier at peak rating.

How Many Watts Do You Need For a Subwoofer?

The one thing you absolutely should make sure of is that you get the right watts for the subwoofer system. Here is a basic guide you can follow:

  • For the aftermarket receiver, you should have a power of around 200 – 300 watts RMS
  • For amplified speakers that work on 50 watts RMS per channel, you can start with 250 – 500 watts RMS
  • If you have a speaker system that works on 100 watts RMS per channel, getting a subwoofer of at least 1,000 watts RMS is common.


The car subwoofer can take your audio to a whole new level. You just need to follow the instructions as carefully as you can to make sure that it is connected properly. If it seems overwhelming to you at first sight, just take it one step at a time. It’s pretty straight forward if you follow the instructions. Once the subwoofer system is installed, you can play your favorite tunes with amazing bass, high-quality audio.