How to Install a Subwoofer to a Factory Stereo: A Quick Guide

photo of a stereo with subwoofer
07th Dec,2019

A factory stereo system could have a very disappointing bass. The solution to this is to install a subwoofer to the factory stereo. 

I know what you’re thinking, just how hard is it to do this? Not a lot of us are savvy techies, so we’re here to guide you through it step by step.

Before you even install a subwoofer, you might be wondering if you need one and what difference it would make.

While there are audio gadgets that can perform well without it, like some good non-subwoofer soundbars, having one certainly has benefits.  A subwoofer enhances the audio experience and improves the performance of the speaker at higher frequencies. The music will be more toe-tapping and have more depth as well.

If you’re looking for specific products, here are our top-rated recommendations for shallow mount subwoofers, if you’re considering going this route.

Another huge advantage of a car subwoofer is it can go anywhere you go. Install one in your trunk, under your seat, or just place it in the backseat. 

When it comes down to it, they don’t have spatial constraints. Although the largest benefit is still the enhanced sound.

interior of a car

A Guide for Installing a Subwoofer to a Factory Stereo

What You Will Need

You might need to get a separate amplifier⁠—like these top-performing 5-channel amplifiers⁠—⁠unless you have an underseat car subwoofer. 

Let’s take a look at some of the tools you will need.

  • Subwoofer box
  • Basic toolbox
  • Speaker wires
  • Amplifier
  • Subwoofer speaker
  • RCA cables
  • A few small screws
  • Inline fuse of 50 amps or higher
  • A wiring kit

Once you have all of these, you should be good to go.

On the other hand, if you don’t have exactly what we suggest on the list, there are a few things you can use as a substitute. For example, instead of two RCA cables, you can use just one with the red and white. And instead of a wiring kit, a 10 gauge or or thicker insulated wire would work too.

Choosing an Amplifier and a Speaker

You would need an amp and a speaker that can pump out max power without blowing each other (or itself) out. 

It’s important to note that just because an amp has an 800 watt power rating, for example, doesn’t mean it should be blasted to this extent. It also shouldn’t be at this high of a power continuously. 

Another thing – the power output rating for the amp is referring to speaker impedance, NOT how much power the subwoofer can handle. So, that’s something to keep in mind when you buy an amp.

To get the best results, the RMS of the amplifier and the subwoofer should be close in number. What is the RMS you ask? Basically, it’s the power output the speaker is capable of without blowing out or distorting the sound. 

In other words, the RMS refers to the power that the amp can handle before overheating. Try to keep the ohms (the impedance) the same for the best results. Lower impedance means more energy exerted to push the speaker or subwoofer.

speaker with wires connected to it

The Wires

To get power, you need to hook up the subwoofer to your car battery and NOT the fuse box. Or else, all you will get is the amplified engine sound through your speakers. 

To do this, pop open your hood and find the firewall. It’s close to the windshield and looks like a metal wall. Thread the cables through the hole in the firewall but keep enough wire on your side to reach the battery. 

After that, remove the insulation from the end of the wire. But don’t connect it to the battery just yet. We’ll get to that in a bit.


Remove your stereo unit from its resting spot and flip it around. You should see the RCA inputs. You need to connect the inputs through the back of that and plug it into the backside of the stereo. 

As for the remote wires, there should be one (or two) blue ones. If there are two, one is for the amp. If you have a power antenna, then you might need to cut into the blue wire.

Speaker Part

Put the speaker back in its place and make sure the gasket is still on it. Secure it in place by screwing it back in and place the subwoofer in the trunk. If you are left with connectors, you need to make sure to wire them into the speaker as well.

car sound system

Almost Done…

Now just a quick cleanup. Wire the amp and connect the power cable to the battery. Place the large fuse in the fuse holder and put the wire between next to the battery clip.

Test it out and once everything looks good, you’re free to listen to booming bass from now on!


Nevertheless, the work doesn’t just end there. Of course, you need to maintain the condition of your subwoofer. 

Cleaning the subwoofer is the best way to maintain it, so make sure you have a lint-free cloth (preferably microfiber), a soft brush, a small handheld vacuum or one with a suction pipe and nozzle, and ammonia.

Use a dry cloth for the exterior. The lint-free cloth and ammonia come in very handy, especially since ammonia is useful in keeping surfaces dry. 

Unscrew the grille and clean the interior with the vacuum carefully. Be wary of this part, and don’t remove the grill if you aren’t 100% confident you will be able to put it back. 

You also have to be extra careful when you clean the cones. Use soft brushes and don’t overdo it on the cleaner. The cones are fragile and cannot be replaced if damaged, so take extra care in every cleaning step as you don’t want to damage any of the components. 

And if you’re less confident, just cleaning the surface will suffice, especially if you keep your car pretty clean anyway.

loudspeaker being connected with wires


Finding the right subwoofer is hard enough, which is why we simplify the process with this guide. And aside from the installation, you also have your work cut out for you in finding a matching amplifier.

Remember, if the steps aren’t clear cut and you are less than confident in your abilities, then spending a bit of cash and getting a professional to do it for you could be the better route. 

After installation, remember to test all the wiring and make sure everything is working before you head home. 

Ah, the lengths we go to in order to get good bass, right?

William Johnson

William Johnson is the owner and founder of He writes about car accessories, with his passion stemming from a deep enthusiasm for all things automotive. His website, RRD, focuses on in-depth reviews of car accessories to help people find the best and latest products in the market.