Step-By-Step Instructions For Installing An Amplifier In Your Car

For quality sound and avoidance of technical mishaps, you need an amplifier installed in your car. However, you don’t need to pay someone to come and do the wiring for you; it’s an easy project that you can simply carry out by yourself.

Before we start our day’s project, let us check out these few details.

  • First, we need to know the accessories needed,
  • Second, we should know where and how to install the amp

Accessories Needed:

Mostly, when you purchase the amp you get a fully loaded kit, but in case it doesn’t come with the kit, you will need:

  • Power supplying cable
  • An in-line fuse
  • Speaker wires
  • RCA cables
  • An earth wire
  • Turn-on switch/wire
  • Connector plugs

Where And How To Mount/Install The Amp:

The size and type of car you own will help you settle on a specific amplifier and where to mount it. A majority of car owners mostly fit the amplifiers the car’s luggage compartment. But if you are driving a model like an SUV, this means you will have to reconsider the mounting due to space limitation. For such sizes of cars, mounting of the amplifier is mostly done underneath, between or behind the seats.


Fix your amplifier at least three feet away from the car’s stereo. This is because it sometimes interferes with the radio’s AM/FM receiver. Also, the distance kept between the amp and the stereo helps to avoid noise spread out from the car’s electrical system.

Also, consider is the amount of heat the amp produces; thus, it should be mounted in a place where there is enough supply of air. If you will have your subwoofers inside the box, it is advisable to have the amp fitted on that box.

Also consider the route your cables will follow while connecting the head unit and amplifier for electric power supply. The most common, easy and safer way to run these wires is underneath the floor, under the dashboard, kick panels, or door scuff plate.

When running RCA cables, always route them far from the power supplying cables to avoid interference between them and the power cables. And when wiring for power, consider where your battery is located in the car to make a direct path of wires to it.

Mostly when routing the power wire, it is advisable to use the existing holes for the current wiring. In case you find this impossible, then you can just drill another hole but in the firewall.

Installing The Amplifier

It is now time for our primary task of the day. If all the above information is taken into consideration, mounting the amp will be a walk in the park. The size of the wire your need depends to where you will locate your amplifier.

Step One: Safety Matters Come First

For your own safety, ensure that the negative terminal is not attached on the car battery to prevent power transmission for electrical shocks.

Step Two: Mount The Amplifier

You can bore a hole where you choose, but make sure you know what is behind the spot you are drilling. Since the edges of the drilled holes can damage the wire, you will have to fit a rubber grommet.

Locate your amplifier appropriately, mark the holes around the amplifier where you will mount and then make the holes. After drilling, you can now use the screws to mount the amplifier.

Caution! Never mount the amp in an inverted position as the heat will radiate to the amplifier

Step Three: Power Wire Installation

For your information, the power and ground wires should be thick enough to accommodate the amp’s required amount of energy.

If there is an unused grommet that leads to the firewall or one with existing wiring but has enough space, you can have your power wire pass through that. In case there is no un-used grommet, drilling a hole in the firewall is another option.

Step Four: Fuse Installation

If your amp’s wiring kit comes minus a fuse installed, then, find a right spot near your battery, but keeping a gap of about 15 centimeters between the two.

Cut off a small piece of wire at the end of power wire, and strip the insulation on both ends of the cut off wire. Use the terminal ring that comes with the kit to crimp onto one end of the wire that was cut off, and connect the fuse on the other stripped end of the wire. Now, take the power wire that leads to the passengers’ compartment, strip off the insulation at the end and connect it to the other end of the fuse holder.

Step Five: Connecting The Power Wire

Attach the power cable to the positive terminal of the car battery, but don’t connect the cable directly to the post. If your kit comes with a wire loom, make sure you coil it around the power cable from the battery to the firewall. Coil another loom over the short power wire connecting the fuse and the battery. Reason for using the loom is because the wire loom protects the cables against the heat produced inside the engine section.

Step Six: Ground Wire Connection

Ground wiring is the most important of all and should always be close to the amplifier. Drill a hole in the metal frame of the vehicle, join an annular terminal to the piece of ground wire, (both are supplied with the kit). Make sure there is no paint or anything that will block conduction of electricity, then, join the terminal to the vehicles metal chassis tightly using a bolt.

Step Seven: Remote Turn-on Wire Installation

Also called remote wire, turn-on wire usually alerts the amplifier to turn on, in most cases when the car engine is turned on and the stereo powered up. It is always located behind the stereo, and for you to access it, you have to un-mount the stereo from the dash.  Aftermarket stereos come with a blue wire as a turn-on switch, some come with a white wire. So, on a small section of the wire coming from the stereo, strip off the insulation, do the same to the remote wire that comes with the amp kit and then join the two.

Step Eight: Signal Connection

Connect your RCA cables to the preamp in-dash receiver output. To avoid any potential noise, try to run the connection cables on the opposite side away from the power cables. Therefore, if there is no any other problem that needs fixing, you can re-install back your stereo on the dashboard.

Step Nine: Wiring Speakers

Speaker signals are not easily interfered with, so you can route the speaker wires near the power cables. For speakers, you can use 14 to 16-gauge wires, and for subwoofers, 12 to 14-gauge wires are okay.

Pass the speaker cables from each amplifier output to the speaker. And for the perfect music output and avoidance of any mechanical issues, let your speaker polarity stay straight; thus, allow the positive wire from the speaker end up on the positive of the amp, and vice-versa. After connecting the speakers, you can now drop all the other wires and attach them to the amp.

Step Ten: Turning On And Setting The Amplifier’s Gain

Be sure of the wiring from the battery to the amp and to the speakers is okay and straight. Ensure there is no stray wire hanging that could cause a short circuit, and also re-check the ground connection to ensure it is secure and tight.

 Turn off all the filters, bass boosters, equalizers and turn the amp’s gain to the minimum, then connect your negative cable back terminal for power. After that, turn on the car engine, listen if every speaker sounds okay once the stereo is on and then turn on the amp’s gain slowly from minimum depending with your receiver’s output level versus the amp’s input level.


You can now enjoy your upgraded system. We appreciated your visit to this site and taking time to follow the step-by-step instructions for wiring an amplifier in your car. We will appreciate even more if you will leave us a comment below.