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Basic Amp Wiring

After a source unit upgrade, the next logical upgrade is to install amplifiers. Its not hard, but follow our guide for some handy tips to make your installation clean and professional looking.

When doing your first amplifier installation the running of the cables can seem rather daunting. Where do I run the cables? How to I make it safe? Do I need to drill holes? Following the DecibelCar.com method you can do your own amplifier power cabling safely using basic tools; wire cutters, electrical tape, a screw driver, knife and small socket set. If you dont have these basic tools, nows a great time to get them.

We’re installing an amp into a Ford F150 pickup truck, so please excuse the dirt and mud.


Step 1. Locate a factory rubber grommet on the firewall, look for one used to delete optional wiring with nothing coming through. If you dont have one, look for a grommet without too much wiring. Typically you’ll want a grommet on the same side as the amp and the battery, to minimise on cable length. Speedometer cable & accelerator cable grommets are ideal.


In this example we’re using the cruise-control circuits cable grommet located next to the brake booster.

Speedo Cable Grommet



Step 2. Using your knife, cut a slit in the unused section of the grommet. Make the slit large enough to accommodate the gauge of wiring your using. 8g & 4g will fit most factory grommets, 0g installations may require drilling holes if you cant find a big enough grommet.

Slit the grommet to fit the cable


Step 3. Now its time for the Pro’s Secret! A fishing rod. Easily made by straightening out a regular wire coat hanger and sharpening one end.

Make a wire fishing rod from an straightened wire coat hanger


Step 4. Now its time to “bait” the fishing rod. Using electrical tape bind the end of the power cable to the unsharpened end of the fishing rod.

Bind the cable to the rod using electrical tape


Step 5. Now guide the sharpened end of the rod through the slit. Adjust the angle as you feed the rod to steer under the dash board and into the floor pan. In a smaller vehicle you may need to get under the dash and find the end.

Feed the fishing rod through the slit


Step 6. Voila! The rods in the foot well area, now slowly pull the rod into the cabin and pull through the cable. Make sure to leave slack to reach the battery terminal.

The fishing rods fed into the cabin, now pull it (and the cable) through


Step 7. Lay out the cable roughly where it will run, try and follow the factory wiring path so you have something to attach the cables and they’re safely out of the way.

Pull any excess into the cabin, but keep it loose so you have room to move the cable around.

Layout the cable before pulling it all the way into the cabinLayout the cable before pulling it all the way into the cabin


Step 8. Now that we have the cable roughly laid out, its time to install the fuse. Always fuse your power runs, and always within 12 inches of the battery to reduce fire risks. Safety First.

Fuse appropriately for the size of wire and amplifier current draw. Add the fuse values on your amps together, and add 20% for a safety net. Our amp has 2x 25A fuses, but we’ll use a 100A fuse as it came in the kit.


Time to install the fuse. We'll need wire cutters and allens keys for this


Step 9. For a tidy installation, we’ve used a split-loom conduit for the cable to protect it from moisture and dirt, and zip tied the cable and fuse holder in place. Follow the factory wiring lines for a neat Pro/OEM install.

Leave the power disconnected until you have the amp fully wired.

Install the cable into split loom, zip tie the cable and fuse holder into place.


Step 10. as this steps different for all vehicles, we’ll skip the disassembly of the dash to install the RCA’s and remote wire. Tape the end of the remote to the end of the RCA’s, so you can route them together more easily, attach the remote wire to the Remote On from the source (typically blue/white or blue) and RCA’s to Sub Out or Rear Out on the source unit.

Connect them behind the dash and route them into the foot well.


Step 11. Now you have the power cable, RCA and remote wire in the foot well. Tape the three wires together at 10-12 inch intervals. Use some more split-loom conduit to protect them and find a route under your dash. Use zip ties to keep them out of the way of your feet, steering column, pedals, levers and any other moving parts.

Again, try to follow the factory wiring harnesses to get the wiring into the kick panel. Remove the kick panel and sills before starting routing.

Use split loom to protect the cables, and zip ties to keep them away from feet and moving parts


Step 12. Using the factory mount points and routes ensures a clean, safe, fit for all your cables. Here the RCA, remote & power wires are routed through the kick panel area following the factory path.

Route the cables along the factory path to the rear of the vehicle (or where the amps located)

Use the factory wiring paths for a clean install and good fitment of panels.


Step 13. Earthing (grounding) points can seem daunting but the factory has already provided you with a number of excellent ones. A seat retaining bolt or seatbelt mounting bolt are ideal!

Simply locate a seat bolt within 18 inches of your amps mount position, remove the bolt, clean the bolts flange, thread, and underlaying body panel with sandpaper or steel wool and bolt down your ground wire.

A seat bolt or belt point bolt make a perfect earth, just remember to clean them first


Step 14. You’re now pretty close to done! Just re-assemble your interior, connect your +12V power cable, ground cable, remote wire, RCA’s and speaker wires to the amp.

Pre-set your amp settings now and adjust them with the system running. Suggested Starting Settings: Gain to 10 o’clock (1/3rd gain), Subsonic On or 30hz (for subs), LPF On and at 100hz (for subs), Bass Boost 0 (for subs), HPF On and at 100Hz (for full range)

Attach all your cables as marked on the amp, pre-set the gains and corssovers, then mount


Step 15. Install and secure your subwoofer and connect it to the amplifier, or install your full range speakers and connect them to the amplifier.


Install and connect your subwoofer or speakers, then secure everything


Step 16. Connect the power terminal to the battery, double check all connections, then power up the system and have a listen!

Adjust settings to taste and go make some noise!

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