How to install an Amplifier and Subwoofer in a car
If you’re installing a subwoofer and amplifier in a factory-amplified audio system, you may have some questions. This is a common modification for vehicles, but before you begin switching wires around and dismantling the existing parts of your automobile, take a look at our how-to guide.
1. Identify Equipment & Wire Placement. You need to run the positive lead to the positive terminal of the battery. Only the driver’s and passenger sides of the footwell have access to the firewall. The driver’s side is optimal, as it generally allows to an empty grommet or the ability to piggyback from an existing cable bundle. If this side’s space is, you’ll have difficulty feeding the power wire to the battery. Use the passenger side footwell to gain access in these cases.
2. Locate a large grommet with ample space.
3. Locate a cargo bin with plenty of room for your device, which will give you easy access during installation, as well as for any future needs.
4. Disconnect the negative lead of the battery, and remove all of the paneling on the side of the vehicle that will house your device.
5. Organize all parts by location, and use bags to store the hardware so you can easily reassemble your vehicle when you’re finished.
6. Disable the subwoofer. Disconnect all factory wiring behind the car’s paneling.
7. Test for factory subwoofer speaker leads. Use the subwoofer speaker outputs from the factory amplifier. Determine which wire to use by visually confirming the wire color at the factory subwoofer and amplifier.
8. Verify wire colors using volt meter and cheater lead. Check out our video Testing for Continuity for further assistance.
9. Test for Phase prior to disconnecting the battery or use a phase detector after removing the battery.
10. Test Speaker Level Inputs.
- Connect your leads to the signal wires you tested earlier.
- Pull the speaker leads and remote turn-on through the factory hole in the carpeting to the factory amplifier.
- Run the power lead through the hole drilled in the grommet under the dash.
***Tip*** Undersize the hole you drill in the grommet to ensure a tight seal between the wires and rubber grommet to prevent water from coming in.
11. Shield the power lead and ensure an original look:
- Use split loom tubing.
- Tie off all wiring to the factory wiring underneath the lip of the firewall to the battery.
- The power lead must be fused in a proper location, which is ideally within six inches of the battery.
12. Mount your fuse to the factory battery mount. See our video How to Wire a Fuse.
13. Ground your connections. The ground lead is connected to the factory ground point near amplifier. To provide an ideal ground, remove paint with sandpaper.
14. Prep the storage compartment:
- Determine the mounting location.
- Drill holes proper holes for the cabling.
- Install plastic bushings to clean hole and protect wiring.
- With all cables run, reassemble the vehicle, and prepare final connections.
15. Prevent sparking:
- Use a test light connected to positive side of battery and slowly charge amplifier’s power supply.
- Before connecting battery, make the final subwoofer connections.
- Prepare the subwoofer speaker wires from the amp to the subwoofer, now connecting negative lead from the battery and testing remote turn-on.
16. Use crimp connectors to make connections. Once connected, turn on the system and adjust gain and crossover settings. Use factory audio settings to fine-tune your new audio system.
To see this information put into action, check out our YouTube video How to Install an Amplifier and a Subwoofer in Your Car – Rockford Fosgate and Kicker.