Car Stereo Amplifier Installation: Car Audio Systems

Tips from Choosing a Location for Your Amp to Placing the Speaker Wire

Installing a new car amplifier is a great way to upgrade your car sound system. Amplifiers take a small electrical signal to make a big signal. The big signal makes for big sound coming out of your speakers. Once you have acquired all of the necessary parts, plan on taking a full afternoon to complete this job. 

  1. Choose a location. It's important to choose a good location when installing your car stereo amp. As a general rule, you want your car audio equipment to be as far out of sight as possible. Although you might want to show off your new equipment, you don't want to turn your car into an easy target for thieves. Most people install their car stereo amps either under the passenger seat or next to the subwoofer box in the trunk. Where you choose is up to you, but if the amp is powering the midrange speakers mounted inside the cabin, it's probably a better idea to install it underneath the passenger seat. Trunk installations are best reserved for when the amp is powering a subwoofer mounted in the trunk.
  2. Powering the amplifier. It is critical that you use sufficient-sized wiring to supply power to and ground the amplifier. Use this guide from to help determine what size wire best suits your needs.
    • Positive Wire (Red): The power wire runs from the positive (+) terminal on the battery, around the engine bay, through the firewall, beneath the carpet, to the location that you've chosen to install the amplifier.

      Install an in-line fuse within 18 inches of the connection to the battery. This is critical. The fuse must be sized appropriately for your amp. Car speakerDon't use a fuse with a rating larger than that of either your amplifier or the wiring to the amplifier. Using the wrong size of fuse is dangerous and can result in fire. Check the amplifier manual for information on your maximum current draw -- this will be what determines the size of your fuse. Don't proceed until you are certain that the fuse is the right size, even if you have to call the company or a professional.

    • Ground Wire (Black): The ground wire connects the negative (-) terminal on the amplifier to a piece of bare metal that is connected to the vehicle chassis. You don't have to run the ground wire back to the battery, because most modern vehicles use the metal frame of the car to ground all of the electronics. Be sure that the ground wire contacts clean metal. Paint or rust will prevent the wire from establishing a good connection and performance will suffer. Since you are almost certainly going to have to drill a hole to bolt the ground wire to metal, be extremely careful where you drill; take some time and know what you're drilling into. Drilling into the gas tank can cause fire.
  3. RCA Preamps. You should have cables with RCA endings coming out of your head unit. You will need to connect wires to these RCA jacks and run them beneath the carpet to the amp.

    Run the wires from the RCA cables on the opposite side of the car from where you ran the power wire. It's important to keep those two types of wires separated as much as possible. In other words, separate power wires from speaker wires as much as possible. If you don't follow this advice, you're almost guaranteed to have a "whine" or high-pitched engine noise in the system due to induction. If your system still has a high-pitched noise associated with it, you can try installing an inline noise filter.

  4. Remote power cable. The blue remote power cable is intended to allow your head unit to automatically control whether your amplifier is turned on or off. It is a small wire because very little electricity actually flows through it. Connect it to the blue wire exiting the head unit. Lower-priced head units may not have a remote power wire. If this is the case, you'll need to install a small switch beneath the dash.
  5. Speaker wires. Finally, run your speaker wires from the amplifier to each of your speakers. Just like with the preamps, be careful to avoid letting speaker wires run too close to power wires. If possible, run the speaker wire on the opposite side of the car as much as possible.

Car stereo installation may seem like a lot of work, but you can save money doing it yourself. Before installing car amplifiers, make sure you have the right amp for your car. Car audio systems differ in quality and depending on your car size, one amp may not be the best for every type of car.


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