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Amp Ed 101: Learning the right way to install an amp

Local students get hands-on training for an amplifier installation

Peter speaking to the class

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.

The Kicker amplifier and subwoofer

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!

While Peter is undeniably good, this is the kind of experience and expertise that our customers get when talking to any of our Sales Advisors or Tech Support team. They know their stuff!

Amplifiers 101

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:

  1. 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.
  2. 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.
  3. Speaker wires then carry the amplified signal out to the speakers.
Photos of the install in the garage

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.

Power, signal, and ground wiring

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.

Peter and the CATEC crew

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:

  1. Why wiring matters, and
  2. 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 via phone, chat, or email. 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.

  • Wayne from Ogden, Utah

    Posted on 5/24/2015

    What does it mean when my sub has two channels

  • Alexander Hrabe from Crutchfield

    Posted on 5/26/2015

    Wayne, Subs aren't categorized by channels like amps are. You may be thinking of a dual voice coil sub, which opens up your options for wiring. Here's a full explanation of dual voice coil benefits.

  • robert jahnke from Bergen County, NJ

    Posted on 6/10/2015

    Question: Is it possible to purchase th FM tuner only sector of a car unit, such as th Blaupunkt Toronto, where it could be tied into an integrated amp for use as a portable home/backyard type of thing? Reason: Quite a few years back I read an article in Peter Aczel's 'The Audio Critic' pertaining to high-end FM tuners. Some of th tuners they were testing and reviewing cost in excess of $1000.00... for a tuner! Not that I'm knocking FM music here in th 21st century, I've been a big Audio nut since my teen years in th early 70's when th Marantz 10B tuner was held up as th pinnacle of th relatively new component world of Audio. But one of th best attributes regarding The Audio Critic was their advocacy of value in th audio world and respect for th buyer's wallets. So, when Peter Aczel went nuts over th Blaupunkt Alaska RDM-168 car unit for $360.00, it got me thinking. I've recently gotten into th DIY field of speaker building here now in my semi-retired years, and I've gotten some very good info from this site as well. Thank you. So, I guess I'm going a bit beyond DIY speakers here, but I've always been amazed at th great FM sound one gets from most car units because, lets face it, we're talking about a moving target here. So... whatever information you could offer here would be greatly appreciated. Thanx - Bob

  • Alexander Hrabe from Crutchfield

    Posted on 6/11/2015

    Robert, the answer to your question in no, we don't sell the FM tuner separately from a car head unit. If you like the idea of building your own radio, there are hobbyist sites that might sell what you're looking for. Alternatively, you may find some used deals on eBay if your aim is to crack open a head unit for parts. All that said, you may be just as happy with one of our home am/fm tuners and adding on a long-range antenna. That combo wouldn't run you more than $500, a little more than the Blaupunkt you mentioned. Worth a look?

  • Scott Crumrine from Yulee, FL

    Posted on 8/4/2015

    Looking at the wiring diagram in the picture, why are there 2 colors (blue & green) for the cables marked "Signal"? It might help if you put arrows on these cables to show if the signal is going "to" the Amp or "to" the Radio. Also, why don't you show the sub-woofer? I assume another set of wires goes from the Amplifier to the Sub-Woofer. You might want to redraw the wiring diagram to make this more clear.

  • Alexander Hrabe from Crutchfield

    Posted on 8/5/2015

    Scott, the green and blue lines are meant to represent left and right channels from the RCA cable. It would be better for us to use only one line in this case. We were only trying to illustrate the wires needed to feed the amp (power, ground, audio), and not make it more confusing by showing the subwoofer too, although you're right, we probably should have. We'll see if we can get this diagram updated.

  • Gerardo Cienfuegos from Moreno Valley

    Posted on 9/5/2015

    I am currently running a 1200 2 channel amp to run my kicker 15" sub. I swapped out the tweeters , front and rear speakers and still have the stock stereo which are powered only by the factory amp. I want to add the Alpine 180 watt , class d power pack to power all my speakers and radio. I need to know how to install this .

  • Alexander Hrabe from Crutchfield

    Posted on 9/8/2015

    Gerardo, if you bought your Power Pack from Crutchfield, you can call Tech Support for free help with installation. If you purchased it elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.

  • Brad S. from Richmond, VA

    Posted on 12/13/2015

    Obviously it's important to separate the power wiring from the signal wires to minimize the potential for noise. My question: In the example above, how do you limit the potential for noise in the driver side front and rear channel speakers with the amp power running on that side of the vehicle?

  • Alexander Hrabe from Crutchfield

    Posted on 12/14/2015

    Brad, do your best to distance the signal and power wires when possible. If that's not possible, there are a number of products available like wire shielding and braided wire that help reduce noise.

  • Gary Arnold from Las vegas

    Posted on 8/21/2016

    How would I run a pass through amp I have rca coming from deck to pass thru amp in the spot marked pass thru then anouther set of rca running from the other spot for rca to my other amp that is connected to my subs is this right or do I have mixed up

  • Alexander Hrabe from Crutchfield

    Posted on 8/24/2016

    Gary, that should work. If you have a "Sub out" output on your receiver, you could run RCAs directly to your mono amp and that would allow you to use sub level and crossover controls you may have on the receiver. However, since you've already laid the cable, using the pass-through feature you described will probably be easier.

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