Adding an amplifier to a car audio setup, allows the components to receive a higher flow of power. Not only will there be more voltage, but the volume will receive a boost on top of the improved sound quality streaming from the speakers.

A 4-Channel Amplifier is designed to manage four different speakers – usually a front and rear set. These amps can also be bridged to give more power to 2 channels that are sharing the workload of a speaker between them.

Proper amplifier installation will create these traits but will help safeguard your entire car from system overloads or circuitry shorts. The following steps will guide you through an at-home install and how to check if your pre-existing amp is properly connected. 

For an amplifier to function properly, it needs three major connections; One to power, another to input, and to an output. 

What Do You Need

Don’t forget to collect the necessary tools and wiring before starting the installation. It’s better to have more wire than you think you’ll need – particularly if you chose to mount your amp in the trunk. 

Take a length of wire and mock-run it from the car battery, along the floor or door panels and to the amplifier. Before you cut your wires, give yourself a few extra inches of slack for mishaps and miscalculations. 

In total, you’ll need 8 wires. 4 pairs, one to connect each speaker to one amplifier channel.

Step 1: Disconnect the Negative Battery Terminal

Disconnecting the power protects both you and your gear.

Step 2: Find a Suitable Place to Mount the Amplifier

What Is The Best Way To Mount A Car Amplifier Under The Front Seat? | Car Audio Q&A

Amp placement will have a significant effect on the unit’s lifespan. One of the most common locations is under the driver’s or passenger’s seat. This method not only keeps your car looking factory by hiding the amp, it also allows for a central location where you can route all your speaker wires. 

Since amps crank up the energy to deliver the right amount of power to the speaker, they can generate heat. Set it up in a location with decent ventilation. Installers recommend placing it under the seat or in the trunk of the vehicle.

For an amplifier to function properly it needs three major connections; One to power, another to input, and to an output. 

Depending on the mounting location you’ve chosen, the car seats and carpet may need to be removed for ease of access.

How to Properly Ground a Car Amplifier | Good & Bad Examples | Car Audio 101

Step 3: Connect Ground Cable

The next primary connection will be grounding the amplifier by wiring a lead to the car’s metal chassis. Look for a nearby metal bolt on the car’s chassis and fasten the ground cable to it. If you can’t find a bolt nearby, drill your own screw somewhere close to the amp but still in contact with the metal chassis. The ground terminal needs to be in constant contact with the car’s bare metal, so you should sand away paint and material at the point of contact for the best possible connection.

Step 4: Connect Power Cable

With a ring terminal, connect the wire to the positive battery terminal and secure it with a nut. Take the other side of this power cable and connect it to the fuse holder. From the other side of the fuse holder, connect and run the wire to the amp’s positive terminal. 

On most vehicles, you should be able to run the wire through the firewall that protects the engine from the main cabin with an existing entry hole. Run the wire on the floor of the car under the carpet to your amplifier.

Step 5: Mount the fuse holder close to the battery for easy access 

This can be screwed to the side of the car’s chassis.

Step 6: Connect Remote Turn-On Wire and RCA cables on stereo

What is an Amplifier Remote Turn-On Wire?

Plug in your RCA cables to the corresponding jacks on the back of your stereo. They could either be labeled as Left or Right, or color coded. Usually the lighter color will indicate the Left channel. If there’s any confusion – take some masking tape to make your own labels. 

Now, take the blue and white Remote Turn-On wire on the stereo wire harness and make a connection to another piece of blue primary wire. This wire will connect back to the amp and power it up when the car’s accessory battery is turned on. 

If your factory radio doesn’t come with this remote turn-on terminal, the wire will need to be connected to your vehicle’s fuse box.

Run these cables on the opposite side of the car from the power wire to input on the amp. This should keep excess noise from ruining your audio. Now the receiver has an audio source.

Consider a Line Output Converter

An LOC is particularly helpful if you’re choosing to keep your factory radio. With the original speakers removed, your stereo will no longer detect the load from the OEM and “shutdown.” To counter this, add an LOC that will present a load to your stereo while also converting its speaker inputs into RCA inputs for your amplifier to understand. 

Read on: How to Install Component Speakers and instructions on panel removal.

Step 7: Connect to Speakers

Cut the speaker wires, leaving enough length to move the wire and to have enough length to connect to the wire freely. Do not make any sharp bends while running the wire. 

Strip a small part on both the stereo’s speaker wire and your amp speaker wiring. If using a line-level adapter, connect to the stereo’s speaker output side. Then connect the 4 pairs of wire to the speaker wiring in the harness.

Insert the stripped wire (about 1/4″ of bare wire) into the connectors and crimp them carefully using a crimp tool if you have one. Alternatively, you can twist together wire, solder it, and carefully wrap it with electrical tape or use heat shrink tubing for insulation.

Step 8: Double Check Wire Layout and Reconnect Battery Power

Check and double check all your wire connections from the car battery to the amplifier, the amps’ grounding wire, remote turn-on and RCA from the stereo to the amp, and all the wire connections from the amplifier channels to the speakers.  

Make sure nothing on the car floor or inside the door panels are pinching the wires. This can cause audio failure and electrical shorts that can harm more than just your sound system. 

Step 9: Tune the Amp

Set the levels and gain of each speaker channel.

Read here  for How to Tune an Amplifier.
Looking for the best amplifier for your car audio system? Visit Sonic Electronix, the world’s premier retailer of car electronics and consumer electronics. We’ve sold online since 2000 and are the recipients of various customer service and product awards. Check out our selection of car stereos, amps, subs, speakers, and more from Pioneer, JVC, NVX, Belva, Kicker, Rockford Fosgate, Cerwin-Vega, and more.