Video: how to install a car amplifier

See the basic positioning and wiring of 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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Adding an amplifier to your car audio system doesn't just make it louder—it makes every instrument sound clearer, it makes subs hit harder, and helps raise your soundstage to head level. Check out this overview of a typical installation to see the steps involved when you install an amplifier in your vehicle.

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

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

Video Transcript

How to install a car amplifier

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.

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.

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

Once you've found a suitable mounting location, it's time to install your amp. First, disconnect the negative battery terminal to protect you and your gear during installation.

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.

In most vehicles, you can pass the power cable through the bulkhead 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.

After running the power wire, the next thing to do is run the turn-on wire and signal cables. The turn-on wire is part of your amp wiring kit. It and RCA cables need to be connected to your stereo. Run these cables behind the dash to your stereo. The turn-on wire connects to a remote turn-on wire 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. Most amplifiers these days can do this. In this case, you can just tap into the speaker wires behind your stereo, or if you're lucky, the rear deck speakers. Either way, this will get signal to the amp.

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 securely. The ground wire terminal should be in contact with the vehicle's bare metal. Sand away the paint at the contact point for the best connection.

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 your amp is rated 75 watts RMS or less, you can use your existing factory speaker wires. Run speaker wire from the amp to the speaker wires behind the stereo. That means eight wires, two per speaker.

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 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.

  • 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.

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