How to Hook Up a Subwoofer to a Car Stereo With No RCA Out Cable

Written by james clark
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How to Hook Up a Subwoofer to a Car Stereo With No RCA Out Cable
Hook up a sub to an older car stereo with an adaptor cable. (car music image by Andrey Kiselev from

Most new subwoofers for installation in cars and trucks are equipped with RCA-type audio jacks for fast connections with a stereo or amplifier. This is convenient when connecting compatible equipment in a perfect world, but when the stereo doesn't have an RCA output jack the installation suddenly presents a problem. The solution is to use an adaptor cable with an RCA plug on one end, terminating in positive and negative speaker wires on the other. The adaptor cable is available at car audio stores.

Skill level:
Moderately Easy

Things you need

  • Wrench
  • RCA to standard speaker-wire adaptor
  • Speaker wire
  • Wire strippers
  • Plastic wire connectors

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  1. 1

    Disconnect the negative cable from the car battery using the wrench.

  2. 2

    Insert the RCA plug on one end of the adaptor into the jack on the subwoofer.

  3. 3

    Strip 1/2 inch of insulation off both ends of a length of speaker wire that will reach from the sub to the car stereo, which is also called the head unit.

  4. 4

    Twist the ends of the two strands of speaker wires together with the wires on the end of the adaptor. Match the red wire to the red wire on the adaptor and twist the other speaker wire together with the second wire on the adaptor.

  5. 5

    Push each pair of wires into the opening on a plastic connector, then twist the connector clockwise until the wires are tight inside.

  6. 6

    Connect the other ends of the speaker wire to the positive and negative Sub OUT terminals on the back of the car stereo or an amplifier, if using a separate amp to power the sub, taking care to match the red wire to the positive terminal and the other wire to the negative.

  7. 7

    Reconnect the battery cable and tighten the post with the wrench.

Tips and warnings

  • Be sure to match the polarity of the speaker wires to the connections on the car stereo: positive to positive and negative to negative. For easy reference, the red cable is traditionally used for the positive connection, although it does not matter so long as the wires are not crossed.
  • Always disconnect the battery cable in the vehicle before attempting any wiring project.

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