Amp Ed 101: Learning the right way to install an amp
Local students get hands-on training for an amplifier installation
When we decided to write about amplifier wiring, we wanted to go back to the basics. A great way to do that was to go back to school. We contacted Mr. Johnson, who runs the Automotive Tech department at the Charlottesville/Albemarle Technical Education Center (CATEC), and asked if he was interested in having us teach a class on the proper way to wire a car amplifier. Mr. Johnson agreed, and we were all excited to share our knowledge with students who had such a thirst for car audio information.
Gear for the installation
The school owns a 2002 Chevrolet TrailBlazer, so we decided that we'd show the CATEC crew how to wire a Kicker 12CX300.1 mono amplifier paired with a Kicker 40VCWS122 12" enclosed subwoofer. To complete the installation, we also used Kicker's CK8 amp wiring kit to drive home the point that wiring matters.
A chance to educate
Peter Logan, a longtime trainer for Crutchfield, led the charge with lessons split between some classroom discussion and workshop time. In the classroom, he laid the groundwork as to why wiring is a crucial element for getting the best sound quality and the safest connections when installing an amplifier. He also shared some wiring horror stories that included wiring dangling underneath vehicles, amplifier and speaker damage, and cars actually catching on fire. Peter has seen it all!
An amplifier's primary function is to take a low-level audio signal (a "preamp level" signal) from your radio, and process that signal to make it "bigger." As the students learned, there are three wiring connections required for an amp to properly make the sound bigger:
- Power and ground wires supply the electrical current for an amp. They should be an adequate gauge (thickness) to handle the demands of the amp, and the power and ground cables should be the same gauge. The power cable should also have a fuse holder close to the battery. The fuse rating should match the recommendation from the amplifier manufacturer to protect the vehicle's electrical system. In this case, Kicker recommended a 30-amp fuse for the amplifier.
- One set of wires transfers the audio signal from the stereo to the input of the amp. Depending on the amp, these can be preamp RCA cables or speaker-level wires.
- Speaker wires then carry the amplified signal out to the speakers.
Hands-on training for the crucial connections
With the wiring discussed, the class moved out into the garage to check out how the Kicker gear would be wired into the Chevy TrailBlazer. Peter showed them how to run the power cable through a grommet in the bulkhead, also known as the firewall, in the vehicle. The end under the hood is connected to the positive terminal on the battery. The other end is run under the door trim to the cargo area where the amp would be mounted.
The ground wire had a shorter run, and students connected it to one of the seat bolts that offered some bare metal to the vehicle's chassis. The bolt they chose had some paint on it, so they simply sanded the area to expose the bare metal for the good contact they needed.
Since the Chevy still had the factory radio, Peter instructed the class on how to splice into the factory speaker leads from the radio to get the input signal needed for the amplifier's input. They made these connections just behind the factory radio. The audio cables were run under the door trim on the passenger's side of the vehicle. Having power and signal cables on opposite sides of the vehicle reduces the potential for any noise in the system.
The CATEC crew used this wiring layout in the 2002 TrailBlazer.
Lastly, students hooked up the Kicker subwoofer to the speaker outputs on the amplifier. Many amps can also require a remote turn-on lead wire, which essentially turns the amp power on when the radio comes on. This can be tricky to find because unlike aftermarket radios, factory radios don't include a specific wire for this. Kicker took this into consideration by including a signal-sensing input, so when the speaker leads sent audio to the amp, it turns on automatically. There was no need for a remote turn-on wire.
Essential lessons learned
After a couple of tweaks, Peter and the class had their new sub thumping. As Mr. Johnson and Peter worked through the installation, they were able to illustrate two important lessons:
- Why wiring matters, and
- Why to avoid shortcuts
Improper wiring can lead to things like poor sound quality, amp shutdowns, and even electrical damage to your vehicle. Appropriate wiring lets you get the best sound quality out of your amp, while keeping your system safe. By avoiding shortcuts and taking your time, you can save yourself from future problems.
We at Crutchfield give a big shout out to the amazing staff and students at CATEC! Thank you very much.
We're always here to help
If you need any help selecting a new amplifier, contact us. Our advisors will help you get what you need. And if you have any questions about the installation, our Crutchfield's award-winning tech support is free for Crutchfield customers, and available for a small fee if you purchased your gear elsewhere.