Guide to Installing An Amplifier in Car Audio System

Last Updated on November 16, 2023 by CarAudioHunt

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Better stereo sound demands installing a car audio amplifier, yet putting an amp in a car may not always present you with the sound you desire because of connection errors. An amplifier requires several wiring connections throughout the car and other challenges. Following this guide, you can only do them from scratch with proper knowledge of equipment and wiring.

So, are you ready to crank up the volume? This installation guide will help you hook up an amp to your car stereo, and finally, you'll have an incredible musical journey. So, let's get started!

Some people doubt setting up amplifiers because they can plainly hear their speakers in any condition. But it's about more than just the volume. The built-in or after-market head unit has a restricted power consumption capacity. However, the speakers require more power to run at lower frequencies.

Amplifiers distribute the electrical power adequately and supply ample power to each speaker. As a result, the sound gets more clarity and dynamic range. There is no way you dislike it when the music clarity never gets compromised owing to the volume up and down.

Important Points to Consider Before Amp Installation

It is equally important to focus on the key items and facts related to the amplifier setup . Disregarding these basics can cause unwelcome interruptions in the middle of the setup.

1. Must Use Accessories

Hooking up an amp depends on the availability of necessary accessories. So, what amplifiers you are going to mount highly depends on what accessories you have to power up the amplifier adequately.

  • The Power and ground cable are important regarding safety issues. Both the cables must have a proper gauge according to the amplifier’s specifications.
  • RCA cables are responsible for transferring audio signals from the head unit to the amplifier. So, try to gather the best ones.
  • The speaker wires serve the connection between amplifier and speakers.
  • You need a remote turn on wire because it is responsible for transmitting on/off signal to the amplifier.
  • An in-line fuse and its holder. The fuse keeps the entire vehicle safe in case of any short circuit in the power wire.

Lastly, you’ll require the Uni-bits (if there are no factory holes), grommet to secure the holes, zip ties and wire loom for wire safety, wire trim from cutting the wire, and trim pry tool for taking the trims off.

2. Picking the Ideal Spot

Putting the amp in an ideal location determines almost the whole process of mounting and routing up a car amp. A safe and secured mounting place is required for the passenger's safety. Also, there has to be a minimum 3 feet distance between the amplifier and subwoofers to avoid noise distortion.

But we recommend putting it into the trunk or behind the back seat. Otherwise, overheating issues will arise if you put it under the seat or cover. No wiring comes into view of the passengers.

Simplify Your Work for Effortless Installation

After acquiring all the required equipment and selected an optimal location for amplifier placement, it’s time to proceed the setup. We recommend ensuring preparedness with mountings and wire routing path, as routing and connecting wires are crucial for seamless connection. That’s what our objective here, making the wiring as easy as possible. So, Let's do 5 pre-installation task here:

1. Isolate the Battery

The negative terminal of the battery can cause unfortunate electric shocks and damage to the wiring. So, use a socket wrench to disconnect the nut of the negative terminal and then detach the cable.

2. Hook the Amplifier on Pre-selected Spot

The trunk floor behind the back seat of any car is an ideal spot for mounting the amplifier. Because laying the amplifier flat allows for easy disconnection of the wiring, it's not possible if you mount it vertically. Now, use a Uni-bit to drill the mounting holes for securing the amplifier on the floor. You must remember to avoid mounting directly on the floor. Keep a thin carpet or anything non-conductive under the amplifier.

3. Mount the In-Line Fuse and Holder

We recommend installing an in-line fuse and holder close to the battery. Because you can easily mount it there, and if any overdraw of electricity happens, the fuse will protect the power cable between the in-line fuse and battery.

4. Preparing the Ground Connection

The ground wire needs to be connected directly to the metal of your car. Now, you should drill a hole in the metal body and attach a nut. If metal nuts are already on the floor, then you can avoid this process. Also, sanding metal bodies to remove color, rust, and coating is necessary as they work as insulators.

5. Remove the Door Seals, Trims and Seatbelts

The trim pry tool helps to take off the kick panels, door seals, and seatbelt panels. Also, It does well tucking the wires in the door seals, trims if you don’t want to remove them.

Complete the Car Amplifier Installation In 4 Steps

Everything has to be neat for the amplifier installation process and you must ensure it by doing all the pre-wiring tasks we’ve mentioned. Now, Let's see the overall installation process:

Step 1: Installing the Input Wiring of the Amplifier

Input wires are the ones that go into the input part of the amplifier. It's common practice to accidentally put the input wires in the output connections on the amplifier. We have included all the input wiring installation in one step to simplify the process.

Insert the Power Cable into the Bonnet

The negative power connection is already cut off, and the first thing you have to do is to find the factory grommets in the firewall. Lots of factory wires go through the firewall grommets. Now select a suitable grommet for passing the power cable under the glove compartment to the bonnet. Use a shorthand knife to make the grommet bigger for the power cable, and insert the power cable (red one) through the grommet.

Attach the Power Wire to the In-line Fuse

You should pull out enough power cable through the grommet in the engine compartment as it is long enough to connect with the battery.

Now, as you need to connect the power cable with the in-line fuse , cut the power cable in the middle (long enough to cover the fuse to battery distance) and trim both ends using a wire trim. Bringing out the cable strands, connect one end with the In-line fuse.

Pass the Power Wire to the Final Termination Point

It is better to attach a ring terminal to the other side of the power cable that is supposed to connect with the positive terminal of the battery. Now you can connect it, as the negative wire is not connected, there is no risk of electrical power flow. Also, connect the long part of the power cable that comes from the grommet with the output side of the in-line fuse.

Using Wire Loom and Wire Ties

As engines can get hot at a time, you can provide another layer of safety for the expensive power cable. The wire loom protects the power cable from heat and vibration. Additionally, wire ties will keep the power cable attached to the other cables and prevent dangling it in the engine compartment.

Run the Power Cable to the Mounting Point

The engine compartment part is already done. Now, you’ll take the power cable under the glove compartment and run it through the unattached kick panel, door seal, and, finally, under the back seat. Use the trim pry to tuck in the cable if needed. Hopefully, the power wire reaches the amplifier mounting point.

For most amplifiers, you must trim the wire and attach the strands by tightening the screw. Also, you can do it using a ring terminal. Now, connect the power cable to the amplifier.

Connect the Ground Wire

The ground wire has to be the same diameter as the power wire and must be bolted on the direct metal body frame of the car. Following this theory, you already mounted a nut on the chassis. Use ring terminals on both sides of the thick wire and connect them with the amplifier and the bolt.

Connect the RCA Wire

It’s time to connect the RCA wire to the amplifier’s input from the back of the head unit or car radio. Starting from the amplifier end, pass the wires under the back seat and side of the car where you have already taken off the door seals, seat belt, and other trims.

Taking the dash apart has different techniques for various cars. So, it's good to learn how to remove the head unit from any online source. You must connect the RCA to the outputs back on the head unit.

Finding Out the Remote Turn-on Wire

There is always a port for remote wire on the back of the aftermarket head unit. But for the factory head unit, you'll have a remote wire (blue color/white color) connected to a radio harness labeled as REM. In most cases, this wire stays tapped off. So, you can connect the remote wire from the amplifier with it. We recommend trimming both wires and joining them together using a wire connector.

We suggest running these wires (RCA and Remote) to the opposite side of the power cable. Otherwise, you may face noise distortion. Connect them with the amplifier’s input unit.

Step 2: Installing Output Wiring: Amplifiers to the Speakers

Amplifiers and Speakers both have two terminals (Positive and Negative) for speaker wire. So, you must connect the two speaker wires to the positive and negative terminals of the amplifier. Connect the positive wires from all the speakers to the positive speaker wire from the amplifier and the negative wires to the negative speaker wire from the amplifier.

Step 3: Reconnect the Negative Terminal

Finally, it’s time to reconnect the negative terminal cable to the battery. It’s a must to check all the connections again before reconnecting the negative terminal cable to the battery.

Step 4: Ready, Set, and Go: Turn on the car and Turn on the Head unit

You can now start the car and turn on your car and radio. After the radio turns on, check the amplifier’s power light. The green light on the amplifier means the connections are okay, and the red light indicates something wrong. If everything is alright, check the music and try to find any distortion from the speaker. The absence of any distortion signifies an ideally executed installation process.


Challenges may come for different cars during the amplifier installation process, yet following this guide will help you stick to a simple plan. Once you begin, the installation process will get easier than it seems. Don't forget to ensure high-quality wiring to achieve the best sound output.

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