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This article explains how to install an amp in a car with a factory radio. Contrary to popular belief and opinion, you do not need to invest in an expensive head unit before you can add or install an amplifier to your vehicle.

On the other hand, adding an amplifier to a factory radio seems like a lot of work when you consider the process involved.

Without a clear understanding of how this process works, this task may appear difficult or impossible for vehicle owners taking part in this project for the first time.

As you read along, we will share tips on how to hook up amp to factory radio effortlessly.

In the end, you will have the adequate knowledge needed to independently install an amplifier on your car and achieve outstanding results without breaking the bank.

What does an amp do to factory radio?

The function of an amplifier in a vehicle is to take a weak audio signal and then amplify it. Usually, factory radios or CD players come with built-in amplifiers.

However, these amplifiers are not powerful enough to drive the speakers. Hence, the need for a separate amplifier to enhance or boost your vehicle’s audio system.

Installing an amplifier on your vehicle improves the sound emanating from the audio system.

This device ensures your factory speakers or sub-woofers receive additional power that they need to produce clearer (distortion-free) and louder sounds.

Suppose you always experience noise or distortion whenever you increase your audio system’s volume to the desired level. In that case, you should consider installing an amplifier.

Benefits of installing amp to aftermarket radio?

You stand to gain several advantages when you install a new or separate amplifier device to an aftermarket audio system.

  • Improved sound quality: A top-quality amplifier guarantees louder and distortion-free sound. Hence, you can increase volume without affecting sound clarity.
  • Enhances subwoofer’s power significantly: If you decide to connect a subwoofer to your audio system, you need to install an amplifier to power the subwoofer for outstanding performance
  • Gives more power to upgraded/new speakers: Are you also planning to upgrade your speakers? You will need a sufficient amount of power to get the best out of your new speakers. Relying on a built-in amplifier or receiver will hinder your new speakers from attaining optimum performance.

How do you test what amp is best for your car factory radio?

The most common feature or attribute that differentiates amplifiers from one another is the number of channels. This number extends from one (1) to six (6).

Each configuration is best suited for different speaker applications or setups. For best performance, every amplifier must be compatible with the system that it will be connected to.

Usually, for each speaker, you need at least one channel.

For instance, if you plan to install 4 coaxial speakers on your vehicle, you will need a 4-channel amplifier for optimum and uninterrupted performance.

You will also need a separate 1-channel amp, also known as a mono amp, to power your subwoofer.

When you connect your car factory radio with a suitable amplifier. You will have a decent audio system that can deliver excellently on your desired performance

How to Install an Amp in a Car With Factory Radio


  • Amp installation kit
  • Speaker wire
  • Wirecutter/stripper
  • Bojo trim panel tools
  • Electrical tape
  • Universal back straps
  • Flashlight
  • Torx driver
  • A clean rag
  • Small plastic bowl for screws storage


With the necessary tools and adequate understanding of the project, it takes between 1-4 hours on average to complete the amp installation on your vehicle.

How fast you complete the installation depends majorly on your level of experience. If you don’t have enough time to spare or do not understand how to hook up amp to factory radio.

It’s safer and faster to hire an expert.


DIY cost

Your amplifier doesn’t come with the installation wiring. While investing in an amplifier of your choice, do not forget to also pick up an amplifier wiring kit.

The kit includes the necessary wiring (power and ground wires), and it also comes with the fuses you need to complete the installation.

On average, a mono amplifier (1-channel) costs between $80 to $300.

If you are interested in a multi-channel amplifier, on average, you can get a top-performance design between $100 and $500.

You can get a quality amp wiring kit for as low as $50.

Professional cost

For car owners who will like to consult an expert to get the job done, on average, you will spend between $120 and $140 as labor cost.

Installing an amp in a car with a factory radio (Step by step process)

01. Purchase the appropriate installation materials

If you haven’t gotten your amplifier yet, ensure you only invest in a model from a credible and famous brand.

The speaker-level inputs/terminals are important additions or features that must be available on your choice of amplifier.

These inputs are labeled accordingly and are similar to the standard speaker wire terminals.

Also, you will need to pick up an amplifier installation kit. Just as we advised earlier, choose a kit from a known brand.

02. Get the materials and tools in place

Before you begin the installation process, ensure you have all the materials and tools you need for the project in place. Arrange them very close to you for easy reach.

03. Adhere to necessary safety precautions

Before you start working on the audio system, you need to disconnect the vehicle’s battery negative terminal.

04. Place the amp securely in the trunk: The best place to store your amp is your car’s trunk. The amplifier can be placed/mounted at any point or position of your choice.

You may choose between the trunk’s sidewall and floor.

Once you have picked an installation position of your choice, you can then mount your amp.

Attach the recommended screws, to the four pre-drilled holes on the four sides of your amplifier for easy and secure installation.

05. Prep the power and ground wires

The amplifier installation kit comes with all the wires you need. When you open the kit, there is the power wire (red) in there.

Pull out the wire, connect it to the positive battery terminal through your vehicle’s cabin, and extend it to where the amp is positioned or mounted.

The next step is to get the ground wire connected accordingly. The ground wire comes with the amp installation kit.

Not too far from the amp, find a nut or bolt on your vehicle’s chassis and attach the ground wire to it.

When you check the sidewall, right behind the fitted carpet, there is a nut somewhere there.

Ensure you get rid of any material (dirt or paint) that could prevent the ground wire from connecting firmly to your vehicle’s chassis.

You can use the Bojo trim panel tools since they do not damage the bolt’s finish or surface. If you don’t have these tools, a screwdriver or paint scraper can be used instead.

If the ground wire doesn’t touch the metal as advised, this minor issue will alter the amp’s performance.

06. Locate the rear speaker wires

Locate the rear speakers (one speaker on the right and the other on the left). Carefully identify the wires that run through these speakers and use a wire cutter or stripper to open up the positive wire and negative wire.

Run a line of speaker wire to each of the stripped wires, and use electrical tape to hold them together.

Then, connect these wires to the speaker-level terminals on the amp. Ensure each wire is connected rightly.

For instance, the speaker wire extending from the left rear speaker positive wire should be connected into the positive speaker-level terminal/input that is allocated for the left rear speaker.

Also, the left rear speaker negative wire should be connected into the left rear negative speaker-level input.

The exact process should be followed until all the four (4) new speaker wires are appropriately linked to the speaker-level inputs.

07. Connect wires to the speaker outputs

After the successful connection of the amplifier to your vehicle’s audio system.

It is time to connect or link the speaker wires you’re your amplifier’s speaker outputs and connects them to speakers or subwoofer that you want to power. Ensure these wires are connected rightly.

08. Connect the power and ground wires to the amplifier

Pick up the power and ground wires you have prepped at the start of this project.

Next, connect these wires to the appropriate inputs on the amplifier.

Ensure all the connections are firmly secured with the aid of a screwdriver.

09. Reconnect the battery & test run the audio system:

The battery terminal should be reconnected to check if the connection is successful.

In case the amp fails to deliver on the expected performance or doesn’t work properly, disconnect the battery and recheck the wires for possible disconnection or damage.

BOSS Audio Systems R1100M



Are you looking for an amplifier that enhances the audio quality of your radio or adds bass to your audio system at a pocket-friendly price?

The Boss audio system R1108M is an excellent design that you can rely on.

This 1-channel amplifier is built to provide your subwoofer with enough power (1100W maximum power output) to perform optimally.

Also, the wired remote allows easy control of various output functions so that you can achieve excellent sound quality.

Another impressive feature is the variable low pass filter, which allows you to regulate the frequencies that enter the subwoofer.

Highlighted Features

  • 13 x 10.44 x 2.25 inches in dimension
  • 1100 Watts maximum power output at 2-Ohms
  • The BOSS logo illuminates
  • Remote bass knob/control
  • 4 pounds in weight

FAQ’s of How to Connect Amp to Factory Radio

What are the benefits of installing an aftermarket radio?

Investing in a new radio before installing an amplifier may be a bit expensive. However, you will definitely have an excellent result to show for it.

An aftermarket head unit makes it easier to choose the perfect amplifier for your audio system.

You will also have several speaker options or designs to choose from. This allows you to build your audio system from scratch and decide on your desired level of performance.

How important is the power rating in a car audio amplifier?

An amplifier’s power indicates the wattage it can send to your audio speakers.  Before you invest in an amplifier, you must consider the output power.

Basically, you must match the speakers’ power requirements with the amplifier’s output power.

There are important factors you should consider to determine how much power you will need.

These factors include the type (features and design) of speakers you intend to connect to the amplifier, the size of your vehicle, and the sound quality you desire.

What is RMS, and how does it affect audio performance?

RSM (root mean square) indicates the amount of uninterrupted power that is within the speaker’s capacity (what it can withstand or handle).

For instance, a coaxial speaker with a 30 watt RMS power rating means such a speaker can operate with 30 Watt power uninterruptedly or continuously.

Ensure you only install an amplifier with a peak RMS power output similar to or equal to your speakers’ peak RMS power rating.

When you supply more power output than your speakers need, or when you overpower them.

This could affect the speakers’ performance or even damage them.

Why do I need to install an amplifier in my vehicle?

If you are a lover of great sound, installing an amplifier in your vehicle is a great idea.

A top-quality 4-channel amplifier guarantees powerful and undiluted sound for an extended period.

What happens if my head unit doesn’t have the preamp outputs?

An absence of the preamp outputs in your radio or head unit is not an issue. There are alternatives or other methods that you can adopt.

You may decide to invest in an amplifier that has the speaker-level inputs feature. Alternatively, you can make use of a speaker to line level converter.

However, these methods are not flawless as they tend to introduce interruption (noise or distortion). A better approach is to invest in a new head unit that comes with preamp outputs.

What does a preamp output do?

The preamp output actually bypasses the built-in amplifier in your vehicle, ensuring a clean signal is sent to an external amp.


Irrespective of the radio or stereo (factory or aftermarket) you have installed on your vehicle, adding an amp is a great decision you can make.

If you follow the tips we have discussed on how to install an amp in a car with factory radio. Especially if you make use of a top-quality amp and wires.

Asides from getting professional outcomes on a budget, you will also enjoy powerful and distortion-free sound in your vehicle for an extended period.

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