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Amplifier wiring diagrams

How to add an amplifier to your car audio system

Happy amplifier

Some people think that installing an amplifier in their vehicle is hopelessly complicated and best left to a professional. That's an option, sure. But Crutchfield has been helping people realize they can do it themselves for over 40 years.

To that point, here are diagrams for a couple of typical amp installations to help you see how all the separate components fit together to form a car audio system.

The first diagram shows a total system upgrade using an aftermarket receiver, two amplifiers, and a subwoofer. The second is more specific. It shows you how to add a subwoofer to a factory system.

How to wire a full car audio system 

This wiring diagram shows how a full-blown car audio system upgrade gets wired in a car. The system depicted includes new speakers, an aftermarket receiver, a 4-channel amp for the front and rear pairs of full-range speakers, and a mono amp for a subwoofer.

The extra gear you'll need for wiring the amps includes:

Capacitors aren't usually necessary in a car stereo installation but we included one here to show how it would get wired into a system.

Amplifier Wiring Diagram

How to add a subwoofer to a factory stereo

A lot of folks want to add bass to their system without replacing the factory radio, either because it looks good or is impossible to replace. The following wiring diagram shows the additional wiring you'll need to add a subwoofer to a factory system.

Start by getting a subwoofer amplifier or powered sub with speaker-level inputs. You'll need these items for the installation and to give it that professional touch:  

Adding a subwoofer diagram

For further help understanding how to install your sub, check out our short videos How to add a subwoofer to a factory stereo and How to install a powered subwoofer.

Start building your system today

Now that you've seen how all the components and parts fit together, you can knowledgeably shop Crutchfield's extensive selection of car audio gear and start building your system. 

Give us a call at 888-955-6000 and an Advisor will help you get what you need. If you want to learn more about installing amplifier systems, check out our Amplifier Installation Guide.

  • Jason from Edmonton

    Posted on 11/27/2022

    I have a 2004 Sebring and I just added an aftermarket BOSS head unit. I have a 500 watt sub amp and a 10" 1000 watt shallow sub that I removed from my truck that I sold. I plan on adding that as a starting point but eventually upgrading all the speakers, and adding two subs. What is a typical alternator output requirement for this kind of upgrade?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 11/28/2022

    Jason, A general rule-of-thumb for power in a car's electrical system is that one-half the top current capability of the alternator/battery/charging system is available to run accessories like amplifiers. A 500 watt amplifier might need as much as 48A (amperes) of current to run at full volume, so you'd look for a system that puts out a total of over 95A. For more info, check out Headlights dim when the music plays.
  • Dylan from Fairbanks, AK

    Posted on 10/29/2022

    You forgot to add the most critical information about the amplifier wiring - the power wire and ground wire must be identical if possible, at the very least they need to be the same gauge wire, preferably ofc with silver coat or something comparable

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/29/2022

    Dylan, If you can find and afford silver-coated oxygen-free copper power and ground wire suitable for car audio amplifier installation, please let us know how it would improve your amp's efficient operation and sound - and where one might get the stuff. But maybe you meant tinned copper wire, which is common.
  • Patrick from Maricopa, AZ

    Posted on 8/26/2022

    Buck, I have a Kenwood HU that has 6 RCA jacks with 4 going to a Kicker 4 channel amp and 2 going to a 12 inch powered subwoofer in a Titan. The 4 channel and the subwoofer both need 8 gauge power wires. Should I run a (4 gauge?) to a distribution block and then an 8 gauge to each amp? What amp rating fuse do I need for the 4 gauge wire close to the battery. Do I need to run a fuse close to the distribution block for each 8 gauge wire to protect the 4 channel and sub individually ? The sub said to use a 20 amp on the power and the 4 channel 40 amp. Thanks!

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/29/2022

    Patrick, 4-gauge power wire from the battery to a distribution block, and then 8-gauge to each amplifier sounds good. The primary fuse should match the specs of the wire - 4-gauge would mean using a fuse rated no more than 150A. In your case, a 60A fuse - the sum of the two amplifiers' fuse ratings - will work safely. If your amplifiers don't have onboard fuses, you should also fuse each 8-gauge wire at the distribution block with each amplifier's appropriate fuse.
  • Richard from Fort Worth

    Posted on 5/17/2022

    I just purchased a 5 channel amp from Crutchfield and I am keeping my stock stereo. When using the high level inputs, is it okay to use rear channel speaker wires for all required inputs? My stock stereo is only a 4 channel so I have to use the rears for channels 3 and 4 plus the subwoofer. It would save some hassle if I could jump them 3x instead of running wire all the way from the front of the car for input and then running another set of wires all the way back up to the front speakers for output.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/19/2022

    Richard, If the rear channels are producing full-range signal, yes you can use them for your amp's inputs. If the bass or treble has been rolled off, attenuated, then you'll need to find some other source, like the front channels.
  • Chris Hansen from Vaughn

    Posted on 4/3/2022

    If I only have two sets of rca's out of my stereo and am running an jl audio m800/8 should I just run it in 4 channel in mode, or y off rca's to fill up all 8 inputs? I am using all 8 channels out of amp.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 4/4/2022

    Chris, If you have two sets, four total, RCA outputs of your receiver, then by all means, use the 4-channel input setting to get eight outputs.
  • Chris Hansen from Vaughn

    Posted on 3/26/2022

    Running all jl audio equipment. Just asking about rca hook up. Running head unit mm50, has two pairs rca out and one pair sub out. Amps are m800/8 running 6 pair 6.5 m3 and one m10ib5 second amp is 750/1 running one 10w7. Third amp is 600/4 running pair m880-ccx and one m10ib5. Plan was to run one set to m880 second set to 600/4 and third sub rca's to 750/1. Is this the best way? I have heard it's better to run all 8 channels into the m880 but is it worth splitting them up with y's?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 3/29/2022

    Chris, If your amplifiers don't have preamp outputs to help distribute input signals, Y-cords will work.
  • Chris from Anchorage

    Posted on 10/7/2021


  • Christian Aitchison from Belgrade

    Posted on 9/26/2021

    Question about tapping into the factory stereo wires. Are you only tapping into the rear speakers or all the speakers? Also do you plug in the the wires back into the stereo after connecting the line output converter?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/28/2021

    Christian, If you're referring to the "Add a sub to a factory stereo" diagram, you tap, connect to, the speaker wires without cutting them. Most amplifier speaker-level inputs need two channels of input to work properly.
  • R.J. from Syracuse, NY

    Posted on 9/8/2021

    I am looking to replace the current Mach460 system in my Mustang with either components front and rear and 4 channel amp, or full range 6.5 and tweeter as well as sub(s) with mono amp. The question is while shopping what ohm load speakers should be purchased to create the most efficient and clean sounding setup? Part two of the question is wiring the 4 channel to those speakers, series, series-parallel or parallel?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/9/2021

    RJ, Although rarely mentioned, most aftermarket car speakers have 4 ohms of impedance. There are some that are 3 or 2 ohms, but low speaker sensitivity makes them only a little more efficient than 4-ohm speakers. Your question about wiring is irrelevant for single speakers - "series, series-parallel, and parallel" wiring refer to how two or more devices like speakers can get wired together. One speaker gets wired with its positive terminal connected to the amp's positive output terminal and its negative to the negative amp terminal.
  • Rodney Mullinax from Boron, Ca.

    Posted on 8/16/2021

    I have a 4 channel amp, (Blaupunkt) with a sub with a built-in amp, (Underseat JBL) I plan to run the 4ch to my 4 speakers and then the powered sub as well. Can I run a power block to split the power (4 ga. to 2X 8ga.)? Then split the remote turn on btwn them? Also run RCA's to the 4ch amp and run the 2 RCA out from the 4ch amp to the sub amp? Does this sound correct? Thank You

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/17/2021

    Rodney, Sounds good to me.

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