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DIY Installation Tips for Car Stereo Amplifiers

A man with tattoos on his arm holds a crescent wrench as he stands in front of a display of car wheel rims.

The Ultimate Guide to Car Amplifier Installation

If you like working on your car, you’re probably keen to upgrade your car stereo system on your own.

This is a great opportunity to learn more about how your stereo works and how to get the best sound from it. Installing an amplifier and accompanying speakers also lets you develop a few handy skills you can use for future upgrades and tweaks.

While this job is tricky, if you feel confident in your wiring capabilities, go for it! And if you need a hand along the way, don’t hesitate to contact the car stereo specialists here at AudioMotive.

Ready to get started?

What You’ll Need

Car amplifiers usually don’t come with wiring, so you’ll need to buy wiring to hook up your amp to your car stereo system.

Power and Ground Wires

To supply power to your new amplifier, you’ll need to connect it to your vehicle’s electrical system with power and ground wires.

These wires must be thick enough to handle the amp’s power demand. A wire that isn’t thick enough could cause problems for your amp’s operation, or at the very least prevent it from putting out its rated power.

Refer to your amp’s instructions to determine the recommended wire size to use. Wire size is measured in diameters, usually referred to as a gauge. The lower the gauge number, the thicker the wire you’ll get. 

Take time to measure the distance between the car battery and the amplifier so you can get the right length of wires.

An In-Line Fuse

An in-line fuse on the main power cable, within half a foot of the connection to the battery, is a must. This fuse protects you, your car, and your stereo system from a short circuit that could cause a fire.

A typical 16 to 20-foot fuse run is safe using one of the following:

  • 25-amp fuse for 10-gauge wiring
  • 60-amp fuse for 8-gauge wiring
  • 100-amp fuse for 4-gauge wiring
  • 250-amp fuse for 1/0-gauge wiring

Alternatively, look for amplifier wiring kits that suit your amp specifications. Amplifier wiring kits include fuses and matching power, ground, and turn-on wires in one convenient package to help remove any potential for confusion or damage.

RCA Cables and Speaker Wires

Amps typically require RCA cables to get input signals from the stereo receiver’s output. RCA cables come in stereo pairs and a variety of lengths.

When running speaker wires from your amp’s output to the speakers, you can use any size wire from 18- to 14-gauge. For subwoofers, use wires between 16- and 12-gauge.

Your Step-By-Step Guide

Once you’ve got all your components and wiring ready to go, it’s time to get to work!

NOTE: Installation specifics depend on the amp equipment you purchased and the make of your vehicle. When in doubt, call the pros!

Step 1: Disconnect the Car Battery

Your car should be parked on a flat surface with the parking brake engaged. From here, pop open your hood and disconnect the battery, starting with the negative terminal. This will help prevent electrical shorts and shocks while you go about installing your amp!

Step 2: Mount the Amp

Choose a safe location to securely mount your amp. The manufacturer will usually include a few recommendations in their included instructions.

As a rule of thumb, amps produce plenty of heat, so they need a few inches of air space on all sides to help keep cool. Don’t mount the amp upside down! While you might be able to save space, the heat it puts out will just radiate back into the amp, causing overheating and creating a fire risk.

You also need to ensure there’s enough room to connect wiring and adjust the controls. But that’s not all! Your amp should also be at least three feet from your stereo proper to avoid interference and radiant noise. Bolting the amp directly onto your car’s metal chassis is also an invitation for noise problems. Use rubber grommets around mounting screws, or mount to a wooden board before attaching it your car’s body.

Possible locations to mount your amp include:

  • On the passenger-side firewall—use short wires and patch cords
  • In the trunk/hatch area
  • Under a seat

Note that you will need to conceal the wiring for safety and appearance. Depending on the location you choose, you will need to run the wiring under the dash, kickpanel, door scuff plate, or pillar trim panel. These panels can usually be removed by unscrewing and/or prying them up at the edges.

Use plastic wire ties to secure the wiring, especially if behind the dash, to ensure the wires don’t interfere with any moving parts of the vehicle.

Step 3: Install the Power Wire

You will need to route the power wire from the car battery, through the car’s firewall, and through the car’s body to the amp.

To do this, find an unused grommet in the firewall to pass the wire through. Alternatively, you can find one with wires passing through and enough room for the power wire to fit through as well.

If there are no existing grommets to use, drill a hole through the firewall, checking on both sides to make sure you don’t drill into electrical wires or gas lines. Use a grommet on the new hole to prevent damage to the wire passing through the hole.

Step 4: Install the Fuse Holder

If your power wire already has a fuse holder installed, you can skip this step.

If it doesn’t, that’s okay. Find a location to install the fuse holder close to the car battery, ideally less than 6 inches from the battery. Anchor the holder with a screw or cable tie.

Cut a short piece off the end of the power wire. This piece should be long enough to reach the fuse holder from the car battery. Use a wire stripper to strip the insulation off of both ends of the newly cut wire piece.

Take a terminal ring from your wiring kit and crimp it onto one end of this short piece of wire. Attach the fuse holder on the other end.

Strip the insulation off the power wire end and connect it to the other end of the fuse holder.

Step 5: Connect the Power Wire

Attach the power wire to the positive battery terminal.

For a top-mounted battery post, crimp a ring terminal on to the end of the power cable if one is not already attached. Remove the nut from the battery terminal, place the power cable’s ring over the bolt securing the battery terminal to the battery post. Then replace the nut.

Terminal adapters are available for vehicles with side-mount battery posts.

Thread a wire loom over the power cable until it reaches the firewall and cut to fit. Then thread wire loom over the short wire attached to the fuse holder and battery.

Step 6: Install the Ground Wire

Find a bolt on your car’s metal frame close to the amplifier. If you can’t find one, drill a hole for one, making sure you don’t drill into any wires, lines, or the gas tank.

Crimp a ring terminal to the short ground cable. Scrape paint and clean dirt off the bolt location so the ground wire connection is to bare metal. Then bolt the terminal tightly to the car’s metal chassis.

Loose or improper grounding is the leading cause of amp problems for car stereos.

Step 7: Plug in RCA, Speaker, and Remote Turn-On Leads

Plug these leads from the amp to the back of your stereo head unit. If your head unit doesn’t have a remote turn-on output, you will need to connect the turn-on wire to the power wire fused-output terminal.

Connect the front, rear, and subwoofer speaker wires from the amp to the corresponding speakers.

Once all the wires are connected, check that all wiring is tight and secure.

Step 8: Turn It On

Set all the amplifier’s gains to the minimum, and turn off all filters, bass boost, and EQ. Ensure the main fuse is secure. And reconnect your car’s negative battery cable.

Turn on your vehicle and the radio. Check for the amp’s power light. Turn up the music and check that sound is coming from each speaker.

Test the stereo system using the balance, fade, and subwoofer settings on the head unit. Check that each speaker is working without static or distortion.

Set the amp’s gain to match the amp’s input level with the receiver’s output level.

If all sounds good, reinstall the stereo and panelling.

Troubleshooting

Common problems that occur with DIY car amp installations include:

  • Needing to reset the factory radio’s anti-theft security code;
  • A malfunctioning electrical system;
  • No sound coming from the speakers; and
  • Noise coming from the speakers.

To quickly fix these problems, or avoid them altogether, get expert help.

Visit the car amplifier installation specialists for professional and worry-free car stereo upgrades and installations.

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