What Does a Car Amplifier Do

What Does a Car Amplifier Do? A Detailed Guide

An amplifier is an essential component of a car’s audio system. You can find an amplifier built into a car’s audio system, though some models come with a dedicated amplifier.

You might be wondering what a car amplifier does and what makes this piece of equipment so important.

In this article, you will learn exactly what a car amplifier is and how it works. You will also learn why it’s important and how to pick one that suits your needs.

What Is the Function of a Car Amplifier?

A car amplifier is used to boost a car’s audio performance. Car amplifiers come in various shapes and sizes, but they all do the same thing: strengthen an audio signal.

When an amplifier receives a signal that is too weak, it amplifies that signal to ensure it comes out louder. The power of the amp determines the loudness and level of sound distortion.

As mentioned earlier, most car sound systems come with a built-in amplifier. While they might be enough to support your car’s speakers, they are not sufficient for an upgrade. This is because the amplifiers are inside the radio, so they are tiny and not so strong.

The sounds these built-in amps provide are basic and are acceptable for those who simply want to listen regardless of the output, but they do not produce the best performance. So, even if you get the best sounding speakers, you won’t enjoy quality sounds using this basic amp.

This is where a separate amplifier comes into play to increase the sound quality and reduce the distortion. It will also allow you to add subwoofers as it will support the built-in amplifier to handle the new load.

How Does a Car Amplifier Work?

Now that you know what a car amplifier does, you need to learn how it works.

Power Connection and Supply

It might come as a surprise that an amp that utilizes 12v can strengthen signals. Well, the answer lies inside the amp where the voltage is increased, thereby creating more power.

Inside the amplifier, you’ll find a switched-mode power supply (SMPS). This circuitry is in charge of producing the extra power your speakers need for optimal sound quality.

It converts alternating current (AC) to direct current (DC) by switching the input voltage on and off. It boosts the 12V power to about 28V.

Load Resistance

As the name states, speaker resistance load describes the resistance a speaker possesses. It can also be called impedance and it’s measured in Ohms. Smaller speakers have higher resistance, and they have greater ohms.

Larger and more powerful speakers need more current than small ones. Due to the increased current, there is a higher load on the amplifier, so it needs to pull more amps. For this reason, make sure to use the right power cable to prevent overheating and burning.

Audio Input

Another major component is the audio input stages. This is in charge of receiving and processing the signal sent from the stereo. The input stages perform four tasks:

  • They connect the amplifier to the stereos
  • They eliminate unnecessary sounds
  • They possess a crossover that prevents speaker damage and distortion
  • They optimize sound clarity

Amplifier Output

After going through the input stages, the processed signal is sent to the amplifier section to be boosted and then to the speakers.

Amplification Phases and Output

This is the part of the amplifier that increases the signal’s power, which is then converted to sound by the speaker.

The amplifier of a car has output transistors capable of taking on higher currents. These transistors receive volts from the SMPS, then send the final powered signal to the speakers.

Classes of Car Amplifiers

There are four main classes of car amplifiers: A, B, AB, and D.

Each class has different advantages and disadvantages.

What Does a Car Amplifier Do

Class A Amplifiers

This is the most efficient class of amplifiers. They consume the most power, but they produce the least amount of sound. They produce the least distortion and the cleanest sound.

Class B Amplifiers

Class B amplifiers are not as inefficient as Class A, but they do create a noticeable amount of distortion. They provide decent sound quality at an affordable price.

Class AB Amplifiers

Class AB amplifiers are better than Class B in terms of efficiency and sound quality. They also create less distortion. They use more power than Class A amplifiers.

Class D Amplifiers

These are the most efficient and expensive class of amplifiers. They produce no distortion and create the purest sound output.

Channels On An Amplifier

Channels are the pathways audio signals follow to create the output signal. Each channel is an individual pathway that leads to the output of a speaker.

In stereo systems, the channels are in charge of whether the sound comes out of the left or right speakers.

Another feature to consider is the crossover feature, which comes with most amplifiers. With this feature, you can split sending the audio signal between the woofer and tweeter.

The crossover sends low frequencies like the sound from a bass guitar to speakers capable of playing them. Also, it sends high-frequency sounds like cymbals and violins to the tweeters.

The varying types of amplifiers have different numbers of channels ranging from mono to 6. The most popular amps are 2-channel and 4-channel amps. They have different uses, so you need to understand the differences if you are looking to buy an amplifier.

2-Channel Amplifiers

2-channel amplifiers are the most used because they power speakers and provide a decent stereo sound.

They are small, light, easy to install, and quite affordable. These amplifiers are perfect for basic speakers, but if you have more powerful models, they may not be able to handle them.

4-Channel Amplifiers

4-channel amplifiers are more dynamic than 2-channel amplifiers. They are excellent for controlling all the speakers of your car, and you can connect them individually to the speakers.

Conversely, you can bridge the 4-channel amp to power stereo speakers using a subwoofer. In this case, you would use two channels for the subwoofer.

If you decide to upgrade your sound system further, you could simply use the two channels for the extra pair of speakers and buy a different amp for the subwoofer.

4-channel amplifiers are more expensive but can handle more power than 2-channel models.

Benefits of Having a Separate Amplifier

Using a standard built-in amplifier is fine for most listeners, but having a separate amplifier makes the entire listening experience that much greater. Here are a few ways having a separate amplifier in your car is a great idea.

Low distortion

A built-in amplifier does a decent job at reducing distortion when increasing the volume with new speakers. A good separate amplifier can significantly minimize distortion even at the highest volume, so if you hear some distortion at your preferred listening volume, it’s a sign you need an additional amplifier.

Ability to Install a Subwoofer

A subwoofer creates bass waves, which require more power, especially if you want to enjoy the bass. Unfortunately, a car’s built-in amp cannot produce power like that. You can add a subwoofer amp if your car radio cannot connect to a subwoofer.

Best Audio Quality

If you purchased new speakers and want to enjoy them fully, you need a separate amplifier.

Without a separate amplifier connected to your new speakers, you could damage them or hear unwanted sounds.


If your car has a weak sound system, you won’t be able to enjoy your playlist to the fullest. Car amplifiers are electronic tools that boost a car’s audio signals to ensure the output of the speakers is loud and enjoyable.

A lot goes on within an audio amplifier, from the power supply to the output section. Plus, they come in different classes and channels. Adding a separate amplifier goes a long way in improving your listening experience.

Hopefully, now you don’t have to ask yourself what does a car amplifier do?

If you are ready to buy one, here are some of the best car amplifiers for bass.