How to Hook Up 2 Amps with 1 Power Wire [STEPS]

I occasionally receive e-mails and responses from novice car audio obsessives who enjoy listening to loud music and bass in their car. Recently, I was asked by one such car audio enthusiast how to hook up 2 amps with 1 power wire.

It may appear perplexing at first, but it’s not that difficult. I mean, it’s not much different than installing a single amplifier. Here, I will help you learn how to connect two amps with a single power wire by taking you through the relevant steps. Let’s begin.

Things You Will Need

To hook up two amps with a single power wire, you will need access to the following:

• Power wire
• Remote turn-on wire
• Ground wire
• Distribution block

Step 1: Detach the Positive Terminal from Your Car’s Battery

To begin, disconnect the positive terminal from your car’s battery. This will keep anything from shorting out while you work with the various electrical cables.

Step 2: Run the Power Wire

If you choose to run two amps on a single power wire, make sure the power cable is heavy enough to satisfy your amplifiers’ rising demands for electrical current; otherwise, the amplifiers will not function properly or produce their rated power.

A power distribution block is the best – and the smartest – way to connect multiple amps to a solitary power cable. The latter is a cost-effective and convenient way of sharing an electrical circuit from only one input source to many branch circuit devices.

Step 3: Run the Ground Wire

Instead of grounding each amp separately, use a ground distribution block to hook up the grounds of all your amps to just one connection point.

Each amp should be hooked up to the ground distribution block, which should be attached to a suitable subframe ground or chassis that has been milled down to the bare metal, ideally within eighteen inches of the amp’s position.

The ground wires on your amplifiers must be of similar size to the power wires. Furthermore, the cable that connects the ground distribution block to the grounding location must be of similar size to the cable that connects the battery to the power distribution block.

Step 4: Run the Remote Turn-On Wire

A blue wire (usually with a white stripe) placed at the back of the head unit is a remote turn-on wire. Its primary purpose is to “inform” your amp to turn on whenever the head unit is turned on.

Your amp will not turn on without the remote turn-on signal.

The issue is that a remote turn-on signal is not always sufficiently powerful to switch on several amps at once. Connecting the turn-on leads from your amps to a transmitter that is activated by your head unit is a recommended workaround for this problem.

Using a 12v relay is a really neat way to switch on two separate amps at the same time with just one power wire.

Instead of getting power from the head unit, the relay in this case should be hooked up to another generator of battery voltage — either straight from the battery or indirectly from the fuse box.

This effectively isolates the turn-on signal from the head unit from your amps, allowing your amplifiers to switch on and hopefully avoiding any current overload issues.

Step 5: Wire the Head Unit to Your Amp

The outputs on your head unit will determine how you wire it to your amplifiers. If your head unit has several preamp outputs, you can hook up each set to a different amp.

You’ll need to check your amps if your head unit doesn’t have several preamp outputs. Inbuilt amp wiring may include preamp pass-through capabilities in some instances, letting you hook up multiple amps.

In that case, hook up your first amp’s pass-through outputs to the preamp inputs of your second amp, and so on. If your head unit does not have several preamp outputs and your amplifiers do not have pass-through features, you will need to divide the signal between your amps using Y adapters.