How to Wire Door Speakers to an Amp

by Joe Murray

    After you purchase and install a new car audio amp, you need to connect either an existing set or a newly installed set of door-mounted speakers to the amp’s right and left front outputs. The more popular car amps drive four speakers: two front-door units and two backseat units generally mounted on the back deck under the rear window. With the front-door speakers’ wiring already pulled through the door and frame, all that remains is for you to connect the two positive and two negative leads to the amp.

    Step 1

    Detach the speaker wire from your car stereo, making note which side goes to the left door and which side to the right. Tie a knot in the right side wire to aid your memory.

    Step 2

    Run the two pairs of door speaker wires to the back of the amp and fasten to the right and left channel front outputs of the amp. Most car audio amps use push-in sockets: red for positive and black for negative. Most factory-installed speaker wiring uses copper-colored wire for positive and silver-colored for negative. A few others use the same color wiring but put a raised strip on the negative side of the wire. Most car amps have 4-ohm output impedance. Make sure your speakers are the same impedance. The impedance is usually listed on the back of the speaker and on the output terminals of your car stereo. If you replaced the factory-installed speakers, the installation manual should tell you the impedance.

    Step 3

    Turn the balance control on your car stereo from one side to the other to check the sound for balance after your installation is complete. If your left and right balance is reversed, switch the RCA-type audio output plugs, either on the back of the amp or on the back of your car stereo, whichever is easier to access.

    Tips

    • If your speaker wire is too short to reach the amp or you choose to mount the amp in an out-of-the-way spot like the trunk, take the speakers out of their door mounts, remove the old wire from the terminals on the far side and attach them to a string with duct tape. Pull the string to the trunk-mounted amp. Attach new pairs of speaker wire to the string and pull back to the door mount openings, strip the new wire ends and connect to the speaker terminals on each side. Strip the other ends and attach to the amp terminals. You may need to pop the rocker panels open and drill holes to hide the wires along the door frame. If so, use grommets to insulate the wire from the rough metal edges of the holes.

    Warnings

    • Always set the brake and disconnect the red hot lead from the car battery when working with the car’s electrical system. Never use an amp that has output wattage greater than your speakers can handle.

    Required Items

    • Flathead and Phillips head screwdrivers
    • Electric drill and bits
    • Wire cutters
    • 16- to 18-gauge speaker wire
    • Wire strippers
    • Duct and electrical tape
    • Plastic ties
    • Rubber grommets, optional

    About the Author

    Joe Murray San Francisco, CA, US Joe Murray began writing professionally in 1980. As a technical writer, he authored numerous white papers, journals and articles for publications and websites for Hewlett Packard and Intel. Since retiring, Murray has written several home-exchange travel articles for KnowYourTrade.com and CHECtravel, among other outlets. He holds a Bachelor of Arts in philosophy from Santa Clara University. Murray has made more than 50 vacation home exchanges worldwide.

    Photo Credits

    • Jupiterimages/Polka Dot/Getty Images