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How to Connect a Car Amp to a Wall Plug

Have you ever thought about connecting a car amp to a wall plug? Perhaps you’re thinking that a car amplifier is designed specifically to be used in a car, so it’s not possible to use it at home.

But the truth is you can! This might seem puzzling at first, but the process of setting it up isn’t rocket science.

You need to understand the power specifications of your amplifier, then you need to decide which type of power supply to use, how to hook it up to the amp, and finally how to connect your smartphone, home stereo, or other audio sources to the amp.

To make the whole process as straightforward as possible, we’ve pulled together this guide that will answer all your questions on how to connect car amplifier at home.

Can you Connect a Car Amp Directly to a Wall Plug?

The answer is a resounding NO!! You can’t plug a car amp directly into a wall socket and expect it to work. If you do that, the amp will blow up. This is due to the fact that car amplifiers use direct current (DC) while the current in the electrical outlet is alternating (AC).

This is the reason why you’ll need an AC to DC power inverter to convert alternating current (AC) to direct current (DC).

Furthermore, car amplifiers use a remote turn-on-wire to automatically turn the amp on & off to avoid draining a car battery – meaning that needs to be dealt with too.

How to Choose the Right Power Supply Unit for Your Amp

An AC to DC power supply units can be bought either online or from an electrical store. However, you need to check a few things before buying the power supply.

Choosing the right power supply unit for your amplifier depends greatly on how much electrical current (amperage, “amps”) your amp will draw, and on whether you’re going to push the amp hard or push it softly.

That’s the reason why the power supply must produce at least 12-volt DC, and that its amperage rating matches the specified rating of the amp.

Essentially, there are 2 basic ways to go about choosing a power supply for a car amp:

  1. Getting a decent power supply that can output enough voltage and current in order to power your car amplifier. This is a good option if you’re not driving the amp really hard (fine for casual listening).
  2. Estimating the amplifier’s current draw (more in this down below) based on its power rating (highly recommended for when you want serious amp power).

What Voltage Does a Car Amp Need?

Car amps normally run o a range of voltages, not just 12 volts, although that’s usually used as a general reference. In fact, when the engine is running, and the alternator is spinning, the voltage can fluctuate between 12V and 14.4V.

To use your car amplifier at home, you’ll need to invest in a power supply with a DC voltage output of 12V to 13.8V. For casual listening, a 12V power supply is perfectly fine to use.

In fact, when shopping, you’ll find that of most of power supply units in the market are 12V.

Using a power supply unit with a slightly higher voltage than needed will not damage the amplifier, because most amplifiers can tolerate a fair bit of voltage.

It must be noted, however, that when voltage drops to something around 11V or so, your amplifier may shut off or go into protect mode, thus it’s important to always have enough voltage available.

What Size Power Supply Do You Need?

The best power supply for your amplifier is the one that provides the right amount of wattage. If you install the wrong power supply unit, the amplifier might not function properly.

In fact, an amplifier that is not getting enough power will have a hard time trying to drive your speakers/subs. Not only that, but it may also experience a wide range of problems including blowing its fuse, cutting out, thermal shutdown, or going into protect mode when bass hits hard.

The Ampere rating of the power supply unit is one of the most important key specs you need to pay close attention to when buying a power supply for your amp.

Standard wall adapters that are around 1A or 2A aren’t anything to write home about. They’re too weak for car amps. 5A, 10A, and 15A power supply units are dirt cheap and can get the job done for the most part.

Things tend to get a bit expensive when it comes to bigger power supply units that will let you drive a subwoofer with heavy bass. Some of these are easily priced over $100.

However, one of the best options is to use a desktop computer power supply as they’re easy to find, don’t cost an arm and a leg and most importantly have pretty good power output.

If you’re budget-minded, for under $40 you can get a computer power supply (if you shop smart) and use it to power your amp. Most computer power supplies offer up to 30 amps or even more current output making them a great solution. They’re available in a variety of power ratings such as 150W to 500W or more.

How to Estimate the Required Amperage?

To estimate the amount of amperage you’re going to need to drive the speakers/subs, you’ll need to take into account the type of your amp and its efficiency rating. All car amplifiers waste power, and that wasted power turns into heat. For this reason, car amps draw some additional current.

  • Class A amplifiers are the least efficient in terms of power consumption, but they are very rare in car audio because of their high power drain and their low efficiency.
  • Class A/B amplifiers are more efficient than the class A amps and are the most common type. The majority of amplifiers in the car audio market are of the A/B design.
  • Class D amplifiers can reach efficiencies in the 80%+ range. They waste less power (and draw less current) than standard class A/B amps. That’s why they are suitable for high frequency and subwoofer use.

As class D and class A/B car amplifiers are the most used amps, and their efficiency is around 85%, and 65%, respectively, we can use these percentages to estimate the total current an amp would need.

Class D Amps

Estimate amps used by a 100W RMS x 4 amp:

4 x 100W = 400W total. (400W/12V) = 33.33A.
Take into account power waste: 33.33A/.85 = 39.21A

Class AB Amps

Estimate current used by a 250W RMS x 2 amp:

2 x 250W = 500W total. (500W/12V) = 41.66A.
Take into account power waste: 41.66A/.65 = 64.10A

As you can notice, you’ll need a pretty big power supply unit in order to run your amplifier at full power. However, you won’t need such power for the most part.

How to Power a Car Amplifier with a Computer Power Supply Unit

A power supply unit (PSU) is a computer component that looks like a small box with multiple wires sticking out from it and a cooling fan inside. Its main purpose is to convert mains AC to low-voltage regulated DC power for the internal components of a computer. It’s a simple and cost-​effective way to run a car amplifier at home.

In order to use a power supply unit to drive a car amplifier, you need to make sure it outputs 12V DC and 15 Amps at the very least.

Step 1: Turn the Power Supply On

Computer power supply units come in two pin/connectors combinations. There’s the 20-pin connector which belongs to older ATX standard, and there’s the 24-pin connector which follows newer ATX standard. The 24-pin connector is just the 20-pin cable with 4 extra wires to provide extra current.

Wires coming out of an ATX PSU are color-coded according to their voltage making it easy to tell which to use.

To turn a power supply unit on, all you need to do is to use a male to male jumper wire (or make your own wire) and connect the “PS_ON” wire (green wire) to a black ground wire.

The PS-ON wire controls the power supply and allows it to stay on when it’s plugged in. For the old 20 pin connectors, this should be the wire at pin #14. For the newer 24 pin connectors, this should be the wire at pin #16 as shown in the image above.

Now, plug the power supply into the outlet and turn the switch to the On position to make sure the fan runs. If the cooling fan inside the unit is spinning, then your power supply works properly. If it doesn’t spin or if the LED inside the unit doesn’t light up, check which pins you connected with the wire to ensure you placed it correctly.

Step 2: Connect Power & Ground Wire to the Amplifier

Locate 12 V+ wires (Refer to the power supply’s chart to find out the color of the 12 V+ wire) and remove around 1/2 inch of insulation from each end of the wires with your wire strippers. Twist the wires together tightly or use a crimp connector (ring terminal, spade terminal, etc).

Repeat the process with two of the GROUND wires (usually Black).

P.S: Make sure to unplug the power supply plug from the wall outlet before you cut any wires, or else you could get shocked.

 

Next, get a screwdriver and loosen the power terminals of the amplifier, marked “+” and “-. Loosen the REM terminal of the amplifier as well.

Now, slide the ends of your “12 V+” wires into the “+12V” amp terminal, and tighten down the screw to clamp the wires.

Repeat the same process for the “GND/GROUND” wires; Slide them into the “GND” amp terminal and tighten the screw to secure the connection.

Now that the power supply unit running and the amplifier has good power and ground connections, will it turn on?

The answer is a resounding “NO”. The amp lacks the remote turn on wire which is responsible for turning the amp on and off. So, let’s hook it up.

Step 3: Connect the Remote Turn on Wire

On a car, the remote wire receives a 12v DC signal from the factory electrical system of the vehicle when the ignition is in “ON” position. This signal is transferred through the remote turn on wire to the amplifier turn on circuit; when the amplifier senses this voltage, it turns on. Likewise, when there’s no voltage in the wire (meaning the ignition of the vehicle is turned off), the amp shuts off.

1. Use a jumper wire

There are many different ways to turn an amplifier on and off without a remote wire. The easiest of which is to run a jumper wire from the power terminal to the remote turn on terminal (as shown in the image below).

The downside to this technique is that the amplifier will keep receiving constant voltage. Therefore, it’ll keep running and will never turn off until you unplug or switch the power supply off.

The jumper wire should be something like this:

2. Use a jumper wire with a switch

If you’d like to be able to manually turn the amplifier on and off by the flip of a switch, then you can run jumper a wire (between the power terminal to the remote turn on terminal) with a toggle switch. This way, the amplifier won’t draw any power when it’s turned off even if the power supply unit is turned on.

3. Use a line output converter

Using a line output converter with a built-in remote wire is one of the best ways to avoid worrying about turning your amp on and off.

A line output converter, or LOC for short, is a device that converts a speaker-level output signal into an RCA preamp-level signal.

Basically, what this device does is that as soon as radio/stereo turns on, it’ll sense that and gives you a remote output that will trigger your amplifier to turn on. Likewise, when you turn the radio off, it’ll see no signal from the speaker level wires it’s hooked up to and kills that trigger.

How to Hook Up a Car Amp to a House Stereo

There are several different ways to hook up a car amplifier to a home stereo. Each of which depends on your amplifier’s features and whether your home stereo has RCA jacks or only speaker level outputs.

1. Home Stereo with no RCA Jacks + Amp With Speaker Level Inputs

If your home stereo is lacking RCA jacks and your amplifier only comes with speaker level inputs, then you can hook up the amp’s speaker level inputs to the stereo’s speaker outputs.

In this case, the amp’s speaker level inputs will scale down the speaker signal to a low level signal the amp needs.

2. Home Stereo With No RCA Jacks + Amp With RCA Inputs

The only way to hook up a home stereo with no RCA jacks to a car amplifier with RCA inputs is to use a line output converter.

3. Home Stereo With RCA Jacks + Amp With RCA Inputs

The easiest way to hook up a home stereo to a car amplifier directly is when the home stereo has full-range RCA output jacks.

Alex Brown

Hey There, my name is Alex Brown, I'm an LA-based sound engineer with over 10 years experience installing, troubleshooting, and repairing commercial, automotive, and household sound equipment. I've installed highly competitive car audio systems, and everything from navigation systems to full car stereo systems, remote starters, alarms and beyond. I enjoy creating solutions and simplifying everyday needs. I also love helping people get great sounding gear, thereby, saving the world from bad sound one customer at a time.

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