How to Wire a Car Amp & Subwoofer

Amplifiers provide the necessary signal boost to power subwoofers.

Most passenger vehicles come with an array of speakers in the door panels, the dashboard and the rear deck. Car stereo enthusiasts will often upgrade their panel speakers and their stereo unit to provide a better-sounding system. Another way to augment your stereo system is by adding a subwoofer and an aftermarket amplifier. The subwoofer provides the lowest tones of music, and the amplifier provides a boost in signal strength to power both the panel speakers and the subwoofer.

Things You'll Need

• 10mm wrench or Phillips-head screwdriver
• Amplifier wiring kit
• Wiring harness adapter
• Speaker wire

Instructions

1. Disconnect the grounding cable from the vehicle's negative battery terminal.

2. Connect the amplifier ring terminal, from the amplifier wiring kit, to the positive lead post of the vehicle's battery.

3. Drill an opening large enough to fit the power supply cable from the ring terminal in the firewall that separates the engine compartment from the inside of the vehicle. Place a rubber grommet in the new opening to protect the power supply cable.

4. Route the power supply cable through the firewall and into the inner cabin of the vehicle.

5. Remove the vehicle's stereo from the dashboard. Consult your vehicle owner's manual for procedures on stereo removal. Disconnect the wiring to the back of the stereo. Connect the stereo wiring to a wiring harness adapter and connect the leads of the wiring harness adapter to the stereo.

6. Connect the signal cable and turn-on lead to the wiring harness adapter. Feed the two amplifier cables through the back of the stereo mounting dock and down to the floor of the vehicle on the passenger's side.

7. Reinstall the vehicle's stereo. Consult the vehicle owner's manual for installation instructions.

8. Run the power cable and signal cable on opposite sides of the vehicle to the location of the amplifier. An ideal location for an amplifier that is to be connected to a subwoofer is in the trunk or rear cargo space of the vehicle.

9. Route the turn-on lead cable on either side of the vehicle to the location of the amplifier.

10. Connect the power cable, the signal cable and the turn-on lead to the amplifier.

11. Connect the grounding wire (included in the amplifier wiring kit) to the amplifier. Attach the grounding wire to a screw or bolt of the vehicle that is directly connected to the frame of the vehicle.

12. Connect two speaker wires to the amplifier, one to the positive output and the other to the negative output.

13. Connect the speaker wire from the negative output of the amplifier to the negative input of the subwoofer. Connect the speaker wire from the positive output of the amplifier to the positive input of the subwoofer.

14. Place the negative battery cable onto the negative battery lead and tighten the cable's clamp to the lead post.

Tips & Warnings

• Make sure that the output of the aftermarket amplifier is within the accepted range of the subwoofer. Keep in mind that the amplification of stereo will need to be considered with the power of the amplifier in determining if the subwoofer can handle the signal output.

• The 10mm wrench or Phillips-head screwdriver is used to loosen and tighten the grounding cable's clamp. Some vehicles require the wrench while others take a screwdriver to remove the cable.

References

• Amplifier Installation Guide
• Subwoofer Installation Guide