Introduction: How to Install an Aftermarket Subwoofer in Your Car With a Factory Stereo

With these instructions, you will be able to install an aftermarket subwoofer in almost any car with a factory stereo.


Line Out Converter (LOC), Subwoofer amplifier of your choice, Subwoofers of your choice, subwoofer box of your choice, 6ft- 36ft of 0 gauge- 4 gauge wire (gauge will be your choice, length will be determined by distance of the amp from the car battery), 4ft- 20n ft of 8 gauge-18 gauge wire (gauge will be your choice, length will be determined by distance of the LOC from the speaker wires), Fuse Block, 30-300 Amp Fuse (Amperage will be your choice), 8mm- 20mm sockets (sizes needed will depend on car), ratchet, extension for ratchet, RCA Cables, Drill

Step 1: Locate Your Battery

The very first thing you will want to do is locate your battery. Most older cars will have it in the engine bay (under the front hood), while some newer cars may have it in the trunk. If the battery is in the engine bay, you may need to drill a hole in the firewall (the firewall seperates the passengers from the engine bay, typically drilling the hole near the brake pedal or gas pedal without obstructing either). Disconnect the negative wire by using a socket and ratchet to loosen the nut.

Step 2: Wire Your LOC Into Your Rear Speakers

The LOC should come with an instruction pamphlet that should explain how to match up the wires. Add 14 gauge- 18 gauge speaker wire as needed to extend the reach of the wires.

Step 3: Mount Your Amp

Find a place that will be convenient to place your amp. Keep in mind that the amp will need to be near the subwoofers in order to minimize speaker wire length and the resistance in the wire. Somewhere in your trunk or on the subwoofer box would be ideal.

Step 4: Preparing the Positive Wire

After your amp is mounted, plan a route for the 0-4 gauge positive wire from the battery to your amp. Use color wire to distinguish between the positive and negative, red for positive and black for negative are the most common. Do not connect the wire yet. Add a fuse holder to the red wire 1 foot from the end on the side closest to the battery. This will protect your wire and amp from any overpowering that might occur. Do not add a fuse yet.

Step 5: Preparing to Turn on the Amp

Connect the power wire to the positive terminal on the battery using ring terminals. Connect the other side of the power wire to the positive terminal on the amp. Use the same gauge wire, but color black, to connect your amp to ground. The most preferred spot to connect your ground is to the seat mount. Sand about .5"-1" diameter circle around the seat mount in order for the ground cable to make good contact with the car's frame. After the ground cable is connected to the car frame, you can hit it with some clear coat paint in order to prevent it from rusting. Connect the other end of the ground cable to the negative terminal on the amp. Connect the remote wire from the LOC to the remote terminal on the amp. Use the RCA cables to get signal from the LOC to the amp.

Step 6: Adding in the Subfoofers

Put your box with the subwoofers preinstalled in your trunk or desired location in the car. Connect your subwoofers to your amp using 8 gauge- 14 gauge wire. Sound will now be possible through the subs.

Step 7: Powering on Your Amp

Add a fuse to the fuse holder. Nothing should happen as the negative on your car battery should still be disconnected. Reconnect the negative to the car battery. As you touch the ring terminal to the battery post, it may cause a spark. Although this spark won't hurt you, be careful to not touch the positive post at the same time as you touch the negative post on the battery.

Step 8: Tune Your Amp

In order to prevent distortion from getting to your amp, you can use a O-Scope or a SMD DD1. A clean signal is the most preferred. If you use either of these devices, a signal will show up on the display of the device. A clean signal will have a rounded top and bottom of the signal, while a distorted signal will have a squared top and bottom of the signal. If you are more experienced, you can use the ear method to just listen for distortion.