How to Hook Up 2 Amps with 1 Power Wire (Guide)  

Having a perfectly sounding car audio system installed in your car is something that most people dream about and plan for. However, turning an idea into reality can take serious effort and more importantly, knowledge. This is even more true when you are planning on doing something beyond the conventional so that you can get that extra oomph in your car’s audio system. One such thing that a lot of audiophiles ask about is installing two amps. While the applications for that are various, the real question that gets asked most of the time is whether you can install two amps with only one power wire.

In this article, we will be sharing everything that you need to know to connect two amps to a single amp power wire successfully. For most people who are thinking of attempting this, it may feel a bit complicated and difficult, but in reality, it is quite easy to manage. There is not much extra work when compared to installing a single amplifier and we will go through the steps you need to take for a successful installation.

Hooking up multiple amps with one power wire is simple. You just need to ensure that the power requirements are met, and the wires being used are of the same gauge on every step. Depending on your system, you may either be able to connect your amps directly or you need a Y adapter for the data signal.

How to Hook Up 2 Amps with 1 Power Wire

Let us get right into it and discuss all the steps that will need to be taken for a successful installation of 2 amps on a single power cable. The process can be dangerous if you are not careful with the electrical components inside your car.

You want to start off by disconnecting the battery to your car completely. After all, that is what you will be powering your amps with, so avoiding any potential accidents is extremely necessary. Now that we are ready to get started, let us talk about the steps involved in making multiple amps work with a single power cable.

Start By Running the Power Wire

The first thing you need to do when installing 2 amps on your car is laying out the amp power wire that you will be using to power them. Since you will be using 2 devices at the same time, you can expect the power consumption to be double the rated output of a single amp. In case you are using different products, be sure to check the power rating on each amp to know exactly how much power each of them consumes.

The wire you will ultimately choose to install should be one that can deliver a little over the combined wattage of both amps. If you do not do this, your amps will not perform properly and if they do not have any protection systems built in, they may even catch on fire. A simple wattage calculation should tell you exactly what AWG wire would suit your needs the best. (1)

One thing that can be particularly useful here is a power distribution block. This is a smart solution to your problem, and it manages the power input efficiently to ensure that both your amps get power distributed to them equally according to their input needs. It is widely used for all kinds of circuits where a single power source is being used to power multiple devices.

Running the Ground Wire

Naturally, you will also need to add a ground wire to the system with all electrical equipment. This will prevent your power amps from retaining excess power in their body, leading to electrical shocks on touch and even device shorting. While each amp needs to have a ground connection of its own, you do not need to create the entire circuit separately.

A common practice that you can use here is creating a grounding block. This is where the ground wires from both your amps will meet and can then be connected to the car’s body for grounding. Be sure to connect your ground terminal to the bare metal of the car and while you are at it, try to keep the distance between the amps and the ground position to less than eighteen inches. This should be enough length for almost any car out there.

When grounding the system, another thing to keep in mind is that the ground wires on both amps should be the same size as the power wires. Since the power flow through the system is so big, the cables taking away an excess will also be dealing with the same kind of load. This will also apply to the cable being used as ground with the battery so the three sections of the circuit should all have the same size of grounding cable.

Adding the Remote Turn-on Cable

Most amps do not have an auto-start feature and need external input every time to make sure they turn on when your head unit starts. To do that, you need to install a remote turn-on wire that sends a signal from the head unit to the amp every time it starts. Since the amps will not be installed in open view and are either underneath the seats or in the trunk, connecting this wire is mandatory.

Traditionally, a blue wire is used which also usually has a white stripe on it which is connected to the back of the head unit and then connected to the amps on the other end. However, given the strength of the signal being generated by the system, the flow is not strong enough to turn on the amps. This is even truer when you have two power amps running simultaneously.

A common fix for this is to include a transmitter in between the circuit that takes the signal from the head unit and transmits it to both the amps. In the new plan, you will basically have the transmitter connected to the head unit, and every time it turns on, the transmitter will automatically generate a strong enough turn-on signal for both amps.

A relay can be added to make the system flawless and free from any potential issues. A 12v relay is traditionally used as it can be connected directly to the battery or the main fuse box and therefore does not need to request power from the head unit. This will also prevent any overloading issues with the head unit and will keep your devices running safely.

Head Unit Preamp Connections

Now that your amps are getting power, they will need to be connected to the head unit to function. To do this, you will need to connect the amps to the preamp outputs of the head unit. The ideal case here would be to have a head unit with multiple preamp outputs built-in as that would make your amp wiring quite easy.

Alternatively, your amps may also have pass-through capabilities which means you can connect one of the amp wirings to the other and then connect that to your head unit. This is especially useful if your head unit does not have multiple preamp outputs.

Of course, there will also be the case where you will neither have multiple preamp outputs in your head unit nor pass-through capabilities in your amps. In such a case, what you will need is a Y adapter. These are basic RCA adapters that let you connect 1 connecter to two devices. In your case, you will need a Y adapter that has a 1-male to 2-female settings on it. The male part will hook into your head unit, whereas the female part will connect to your amps. Also, be sure to buy a quality adapter with thick wires that can last a long time.

What to Do About the Speaker Wires?

The final step is to connect the speaker wires to the amps and some of you might be wondering how a single speaker can be connected to both amps. Thankfully, once the amps are connected to the system, wiring the speakers to just one of them will provide you access to both the amps. Be sure to check for speaker polarity and match it with that of the amplifier. The positive terminal of the speaker should be connected to the positive terminal on the amp and the negative wire to the negative terminal.

If you are also connecting a subwoofer, then you can connect that to the amp with no speakers on it. Again, it is important that you match the terminals for that. As for the wiring, the gauge you use for the speakers will be one or two steps smaller than that of the subwoofer. Your electrician can guide you on the appropriate size depending on the wattage of your speakers and subwoofer. (2)

Wrapping Up

Your system should now be ready for use. Be sure to consider the wire size on every step and match where it is needed. Use high-quality materials only and it is best to get the entire installation done by a professional to avoid any mishaps.

Take a look at some of our related articles below.

(1) wattage calculation –
(2) electrician –

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About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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