How to install a car amplifier

Learn how to wire and position an amp


Zak Billmeier

Zak Billmeier grew up in southern Vermont and coastal Maine. After graduating from Mary Washington College with a Geography degree he still isn't sure quite what to do with, he eventually settled in the mountains of Central Virginia. He spends his free time chasing his daughter around, taking pictures, gardening and cooking. He joined Crutchfield's car A/V writing team in 2007 and is now a lead producer on our video team.

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Learn how to install an amp in your car

In this overview, we'll cover walk through a typical amplifier installation to see the steps involved when you install an amplifier in your vehicle.

How to install a car amplifier |  video transcript

Adding a car amplifier will let you play music louder. It'll also raise the soundstage and enhance the detail in every song at any volume. Let's take a look at what it takes to install a car amplifier in your vehicle.

In this video, we have one of our tech support advisors helping out. These are the same folks you'll talk to if you have questions during your install.

Find a place to mount your amplifier
Before you get started, find a suitable place in your vehicle to mount your amplifier. Amplifiers generate heat, so adequate ventilation is important. And you'll want to place it somewhere that's not too difficult to access.

Amp wiring kit and speaker wire
Your amplifier does not come with the necessary wiring, so be sure to purchase an amp wiring kit that includes power and ground wiring, as well fuses you'll need. You'll also need to purchase enough speaker wire for the job.

Disconnect the battery
First, disconnect the negative battery terminal to protect you and your gear during installation.

Step #1: Running power wire

Next, run the power cable from the battery to the amp. Cut a short piece of the power cable, enough to cover the distance from the battery to the fuse holder location, and strip the insulation off both ends. Crimp the terminal ring from your wiring kit to one end, and attach the fuse holder to the other end. Strip the insulation from the end of the wire that leads to your amp and attach it to the other end of your fuse holder. Assemble the fuse and holder, and attach the terminal ring to your positive battery terminal. Then mount the fuse holder securely. It’s important to keep the fuse close to the battery since the lead between the terminal and the fuse is unprotected.

In most vehicles, you can pass the power cable through the firewall that separates the engine compartment from the main cabin using an existing entry point. Once you're inside the cabin, tuck the power cable under trim panels or your carpet along one side of your vehicle until you reach your amp location.

Step #2: Running turn-on wire and signal cables

After running the power wire, the next thing to do is run the turn-on wire and signal cables. The turn-on wire is included in your amp wiring kit. Run these cables behind the dash to your stereo. The turn-on wire connects to a remote turn-on lead in your stereo's wiring harness. It's usually blue, but confirm this with your owner's manual. Plug the RCA cables into the appropriate RCA outputs on your stereo.

Run these wires, the turn-on wire and the RCA cable, down the opposite side of the car from the power wire. This will prevent electrical noise from entering your system and spoiling your music.

All of this assumes you have an aftermarket stereo with preamp outputs. If you have a factory stereo then you'll do things differently. First off, make sure your amp has speaker-level inputs and "signal sensing" turn-on capability. If the amp does, you can just tap into the speaker wires behind your stereo, or possibly the rear deck speakers, to get signal to the amp.

Step #3: Ground the amplifier

The third primary connection is the ground wire. This wire should be connected to the vehicle's chassis. Look for a nearby bolt that you can fasten the ground cable to. The ground wire terminal should be in contact with the vehicle's bare metal. Sand away any paint at the contact point for the best connection.

Step#4: Send signal from your amp to your speakers

Now you need to get that audio signal from your amp to your speakers. Run this speaker wire at the same time you run the amp input wires.

If you're powering speakers with more than 75 watts per channel, then you should run new speaker wire from the amp to each speaker. If your amp is only powering subwoofers, then just run speaker wire to the subwoofer box. Either way, use 14- or 16-gauge wire from your amp to your speakers.

Now, mount your amp and make your connections. Try to use gentle curves with your wires and cables when possible.

Before you fire up the amp to test, turn the amplifier's gains all the way down. And if you’ve disconnected any connectors relating to the airbag, make sure to reconnect them. You don’t want to trip an error light that’ll need resetting. Now, reconnect your vehicle's negative battery terminal. Verify that the amp turns on when you turn the car on. Then you can play some music and set your gains.

Remember, if you bought your amp from Crutchfield, you can call our tech support team if you hit any snags. If you have any questions about car amplifiers, please give Crutchfield a call.

For more info on amplifier installation, check out these helpful articles:

For more info on car amplifiers, check out these articles:

Last updated November 16, 2015
  • Kim from Bunnlevel

    Posted on 8/14/2015 9:31:40 AM

    I just purchased a 2015 Ford Focus. Is it possible to add my amp to this system?

  • Buck Pomerantz from Crutchfield

    Posted on 8/14/2015 1:21:02 PM

    Kim, Our Product Information team has not yet researched the 2015 Ford Focus, so I can't say whether or not it's easy, difficult, or even possible to install an amp in your car. Sorry.

  • kevin from solomon

    Posted on 8/20/2015 11:34:57 AM

    How many sub to use with a 4000 watts mono 1 stable ohm

  • Buck Pomerantz from Crutchfield

    Posted on 8/20/2015 12:49:08 PM

    Kevin, I answered your comment on the Sub-tuning article with a suggested two 750-1200 watts RMS rated DVC 4-ohm subs solution. You could also use 4 DVC 2-ohm subs rated for 300-600 watts RMS each.

  • James R. Phifer from carlsbad n.m.

    Posted on 9/2/2015 5:09:42 PM

    What gauge wire for power and ground I have a jbl 100wat amp

  • Buck Pomerantz from Crutchfield

    Posted on 9/3/2015 9:16:37 AM

    James, You'll have to be much more specific when asking about your amplifier's power requirements. JBL does not make any amplifier that puts out just 100 watts, If you are referring to their MS-A1004 4-channel 100 watts RMS per channel amp, then you can use 8-gauge power and ground wires.

  • Piyush from Delhi

    Posted on 11/9/2015 3:10:49 AM

    what is sensing power input on any amp? can we connect through there??

  • Buck Pomerantz from Crutchfield

    Posted on 11/9/2015 4:17:21 PM

    Piyush, I not sure where you got that phrase, but I think you're asking about the automatic signal-sensing circuit on some car amplifiers that use speaker-level inputs. When using the speaker-level inputs, this kind of amplifier senses the input signal and turns the amp's power on. This feature makes it easier to add an amplifier to a radio without RCA outputs or a remote turn-on connection.

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