Amplifier wiring kit buying guide (2024)

An amplifier wiring kit is a collection of the wiring and hardware that you'll need to install your aftermarket amplifier in your vehicle. The size of your amp and the kind of signal wires needed will determine which kit will be most appropriate for you and your system.

W

hen you're building a new audio system for your vehicle, choosing your amplifier (or amps) is often one of the fun parts. But car amplifiers don't come with the wiring necessary to hook them up. The right power wiring, audio cables, and connectors are the keys to installing your amp properly and getting the sound you crave.

Luckily, we offer a wide selection of amplifier wiring kits and input and output signal wiring that can provide everything you need to connect your amp.

What wiring do I need to install an amplifier?

Your amplifier will need wiring for power and ground connections, audio input, and audio output. Amplifier wiring kits provide different options for these connections. Some kits only include the power and ground needs. Others include RCA cables and/or speaker wire for the audio connections.

Everyone's audio system is different, so there's no simple solution for wiring needs. We'll cover each piece in turn and then look at the solutions available.

Power and ground wiring

Power and ground wiring includes:

• power cable
• matching fuse and fuse holder
• ground cable
• remote turn-on lead
• connecting hardware

The first step in powering your amp is a thick power wire. You'll need to run it from your car battery's positive terminal, through the car's firewall, all the way to the amplifier. The required thickness (gauge) of the power wire is determined by the amp's power and the manufacturer's specification – you can look it up in the owner's manual or online. And see our Cable Gauge Chart for more information.

Wire quality is important

For safety, it's important to only use stranded copper wire – usually sold as oxygen-free copper (OFC) wire – for car audio power applications. Copper-clad aluminum (CCA) wire cannot safely handle the amount of current that a copper wire of the same size can.

Power wire fuse and fuse holder

You'll also need to install an in-line fuse or circuit breaker on the power cable near the battery. This protects the power wiring, your car, and yourself against fire. In the event of an accident, you don't want a live wire stretching throughout your vehicle touching ground, sparking, melting, and then igniting. For more information check out our article about the importance of fusing your car amplifier power wire. Remember: "Only fuses can prevent car audio fires."

Power requires ground

Your amplifier's ground wire should always be the same gauge (thickness) as its power wire. Most car audio systems use the vehicle's metal chassis as the grounding point for the amplifier. That means your ground wire can usually be short with the connection point close to the amplifier. If your amp is mounted in the rear of the vehicle, you can usually attach the ground wire to a seatbelt bolt or some other bolt that attaches to the vehicle body.

Loose or badly located ground connections are responsible for more amp noise problems than anything else, by far. Make sure your amplifier is grounded tightly to the main chassis of your vehicle, with all the dirt cleaned off and paint scraped away from where contact is made.

This "chassis ground" connection won't work in some late-model vehicles with unibody construction, so running an amplifier's ground wire directly to the battery may be necessary.

Power ground vs signal ground

All of the above talk is about grounding the power circuit. A different kind of ground, signal ground, completes the signal flow from amplifier, through the speaker, and back to the amp through the speaker wires. Signal ground should be kept isolated from power supply ground, otherwise bad noises like hiss, hum, and buzzing may occur.

What's the blue wire for?

Another wire you need for powering the amplifier is called the remote turn-on lead. This is a thin, usually blue or blue/white wire that carries a 12-volt DC signal from the stereo to trigger the amplifier to power on whenever the stereo turns on. In the case of a factory stereo with no remote connection, you'll need to connect your amp's turn-on lead to a switched 12-volt source (one that only comes on when the car is running) in the fuse box.

Hardware

Running a power cable through a vehicle's firewall will require a grommet to protect the wire from wearing through its insulation and short-circuiting to chassis ground. A good ground connection will use something like a ring terminal to attach the ground wire to your vehicle's chassis. The power wire in some wiring kits comes with a ring terminal already attached to one end for connecting to the positive battery terminal. Some amplifiers' output connections are made neater and more reliable when spade terminals are used on each speaker wire. Power and ground wiring distribution blocks come in handy when you need to power more than one device at a time.

[Read our car amplifier installation guide for more details on all the above.]

Audio input wiring – RCA cables or speaker wire

You need to get the audio signal from your stereo into the amplifier where the amp can work its magic. Input wiring comes in the form of RCA cables or speaker wire. We'll explain the difference below.

When using an aftermarket receiver in your system, your amplifier will need to get its input signal via RCA patch cables. They come in 2-, 4-, and 6-channel models to accommodate different system configurations.

If you're using a factory stereo without RCA outputs, you can get your amp's input signal from the radio or factory amplifier's output wiring, Many amplifiers have high- or speaker-level inputs to accommodate this kind of setup. You can use thin, 14- to 18-gauge speaker wire or a multi-conductor cable (see below) for these low-power connections. Another option is to install a line output converter to reduce almost any factory-amplified signal down to the preamp/RCA level your amp's input can safely use. For more details, read our 8 Common Questions about Line Output Converters article.

Output wiring – speaker wire

At the other end of the amp, you'll need speaker wire. We recommend 12- to 16-gauge speaker wire for your speakers and subs.

A great method of connecting speakers to an amplifier is using what's called "speed wire" or a "9-conductor" cable to connect the amp's outputs to the vehicle's speaker wiring either behind the radio or at the factory amplifier's output connections. The individual conductors may be thin (18-gauge, usually) but the convenience of handling four channels of audio plus the turn-on circuit with one cable vastly outweighs any perceivable power loss. You can also use this kind of cable for your amp's speaker-level input connections.

What if I'm installing more than one amplifier?

You have to supply power from the battery to every amp in your system. You could run separate power wires for each, but the best (and easier) way to power multiple amplifiers is to run a single power cable from the battery to a power distribution block, and then from the distribution block run smaller power wires to each amplifier. This way is neater, easier, and less prone to noise and power problems, which are often caused by loose wiring connections.

You ground multiple amps the same way, using a distribution block that connects the individual amp ground wires to a single ground wire that then connects to the vehicle chassis or battery negative terminal.

In some multi-amp systems, the remote turn-on signal from your receiver could become over-loaded and not work right. In that situation, you'll need to install a relay, like a PAC TR-4, on the turn-on lead, so it'll get triggered on by the receiver but use the 12-volt turn-on signal from somewhere else, like the fuse box.

Your amplifier wiring kit options

Amplifier wiring kits include (almost) all the pieces you'll need packaged together for convenience and low cost, with various options available.

Option 1: Power wiring only kits

In most installations, the signal flow from the stereo to the amp and from the amp to the speakers will be uniquely vehicle-specific and require separate customized input and output wiring. Crutchfield offers over a dozen different power wiring kits for this most-common situation. These kits do not include RCA cables or speaker wire.

Option 2: Kits with RCA cables and speaker wire

For single-amp installations in standard-sized vehicles, some amplifier wiring kits have everything you need to install your amp. They'll have RCA cables for the audio input and speaker wire to run to your speakers from the amp.

Option 3: Multi-amp wiring kits

For larger car audio systems that have more than one amplifier, Crutchfield offers a few multi-amp wiring kits. These kits will include multiple power and ground cables, distribution blocks, and the hardware needed to connect it all.

For more information, check out our Car amplifier installation guide.

Need an amplifier wiring kit? Call Crutchfield

The right amp wiring kit will be the collection of hardware that offers the most compatible wiring products for your amplifier's installation in a single package. If you want help figuring out your amplifier wiring needs or if you have questions about amplifier installation, call or chat with our Crutchfield Advisors. They'll give you precise and professional assistance in making your system perform perfectly and sound great.