What Does A Car Amplifier Do? The Ultimate Guide

What Does A Car Amplifier Do For Car Audio

Car sound systems are incomplete without amplifiers. Take a look around, every audiophile has them. 

They’re one of the three main components of a car’s audio setup: subwoofers, an equalizer, and an amplifier. These three are considered the holy trinity of car audio systems. 

But suppose you’re not an audiophile, and you’re wondering what’s the function of an amplifier and how they work. Here we’ll explain, what an amplifier does to your car’s audio system, how it does that, and the benefits of having one in your car. Here it goes!


What Does a Car Amplifier Do?

What Does a Car Amplifier Do

This is the first question you’d get asked by someone who doesn’t know anything about car amps. Before we get all technical with how a car amp works, let me just break down what the car amplifier actually does. 

To put it simply, a car amp boosts small electrical signals that are emitted from your car’s head unit and magnifies them to higher voltage audio signals. 

The stereos incorporated in cars are typically designed to deliver just 15 to 18 watts of power and still tend to sound very badly distorted when performing at their maximum level. 

A car amp drives the loudspeakers that are connected to the speaker wire with more power, resulting in an increased volume and better sound clarity.

For those of you who like music with loud thumping bass, you must have subwoofers. 

Subwoofers require massive power. Your stereo won’t be able to provide that. The same problem also occurs when you try speakers with a capacity of 4 ohms and 20 ohms (the aftermarket ones) which also require a huge amount of power. 

Most of the time, your car’s stereo falls short of providing that on its own. 

That’s when a car amp comes in handy. Not only does it provide a solution to the power shortage, but it also offers a better sound quality. You’ll have low noise and practically no distortion because it has a state-of-the-art system incorporated. These are dedicated solely to this task.


What Do the Power Ratings on An Amp Mean?

Power Ratings on An Amp

You might notice some numbers and figures on the labels of an amp and wonder what they mean. Well, those are power ratings. The performance of an amp is measured by a unit called an RMS watt rating. RMS stands for ”Root Mean Square” and it’s a term that belongs to electrical engineering. 

It’s used to denote “Alternating Current” or AC signals. These types of signals are prevalent in sound-based electronics. Since AC signals are different from DC (Direct Current) signals, their units are calculated a bit differently. The RMS measurement takes this difference into account. 

Just a fair reminder: The RMS measurement described on the labels of an amp is more of a technicality than fact. The amount of maximum output is never the same in actual use as it is described on the label.

But this whole thing still left some room for confusion. So in 2006, the Consumer Electronics Association (CEA) 2006 standard was created. This meant to fall under the listing of the CEA-2006, manufacturers now actually have to deliver what they advertise on the specifications on the labels. 

This encouraged them to provide more accurate specifications to get a CEA-2006 certification.


How Do Car Amplifiers Function to be Exact?

There are 5 main stages inside a car amp that an audio signal goes through upon entering. They are:
1. A power supply device to step up the power (DC to DC).

2. Especially designed circuitry to prevent noise, AKA “Ground Loop Circuitry.”

3. A well-designed circuitry for speaker crossovers.

4. Again, a circuitry to bridge different parts.

5. Bass boost or any other convenient functions that you want.

Each of these plays its part, and they make the amp work together. Let’s see what they do individually:

The Power Supply

How Does a Car Amp Work - Power Supply

The first thing you must be wondering is how an amp actually amplifies the audio signals after knowing that it only uses about 12 volts of power, just like the car stereo.

Well, there’s no magic behind it. It’s pure science. Or, to be more precise, electrical engineering at work. See, the voltage is increased inside the amp to deliver more power to the speakers.

There’s a special circuitry inside the amp called a switched-mode power supply, or just a power supply for short, which increases the voltage so that the speakers can boost the audio signals that they get from the head unit with more power.

The real magic is that this hidden secret power supply acts as your backup ammunition. Especially when you try to boost your 12V power supply to a higher level. Let’s say, 28V. Two things are at work here to get the job done; resistance load (impedance) and Switched Mode Power Supply (SMPS).

Impedance, or speaker resistance load is what defines how much resistance your speaker has, and it’s measured in ohms. Here, the ratio goes like this, the smaller the speaker, the higher the resistance load, which means a higher ohms rating.

Speakers that are big and have low resistance require a lot of current as opposed to small tweeters.

This puts more load on the amplifier, which means it will draw more power. This also means that it’s crucial to use a power cable that’s got the correct rating for your amp. If the cable is too thin, it can get overheated and burn.

The Switched Mode Power Supply (or SMPS) is what amps use to get a larger amount of power from a 12V power source like your stereo. This is considered the most important part of an amp.

It’s capable of increasing electrical efficiency. It works by switching input voltage on and off at a rapid pace. Yeah, it might sound weird, but that’s actually how it works.

An SMPS can draw more power out of a 12V power source in comparison to a standard or ‘linear’ power supply, increasing the performance of your amplifier in the process.


Noise Prevention Circuits

The circuitry used for blocking out noises, also known as the crossover circuits or the audio input and amp output, is the part where the signal from the stereo is received and processed. Then the circuitry sends the audio signal to the amplifier section to boost it up.

The section of an amplifier dedicated to delivering output is then at work. This section holds the final steps between the original audio input and the amplified audio output.


Speaker Crossover Circuitry

How Does a Car Amp Work - Speaker Crossover Circuitry

Car amps are equipped with larger output transistors that are capable of delivering the higher current required for the extra power you’ll need for a good audio output. Powered by the SMPS, the transistors can transmit a much higher power output signal to your speaker than the original audio input.

They also come with the option of tweaking and controlling the frequency range that they send to the car speakers. For instance, a low pass filter incorporated in a subwoofer blocks out everything except bass to enhance the bass sound of the output.

But that often creates a distorted sound due to the low capacity of door speakers or tweeters. Then a high pass filter prevents the bass from distorting.


Bridging Circuitry

The main sections of a power amp are dedicated to modifying or manipulating the audio signals received from the head unit along with delivering an increased amount of current and power. The first sections consist of small components like little transistors that divide the audio signals that they receive into two equal parts.

Once the signals have passed through all the stages, then they are directed towards larger transistors with high current and higher volts produced by the SMPS.


Extra Convenience Functions

How Does a Car Amp Work - Bass Boost

This stage varies from amp to amp, and they are there to further enhance your audio experience after the amp does its main job.  For example, the different stages of speaker level inputs and bass boost.

When your car’s stereo does not have low-level (RCA) inputs, but you still want to connect your amp to it, then you use speaker-level inputs. It allows you to use the signal coming from the speaker outputs as an input source for the amplifier.

Bass boost is a hugely popular effect used in car amps, and to your surprise, rarely done correctly. The main purpose of the bass boost is to get a more enhanced bass performance out of your subwoofers. Here’s how to do it.

First, set your gain levels to zero. Then toggle the button/switch/dial for controlling the bass. Play the music you want to hear and keep turning the gain up until the sound distorts.

Then turn it down again until it sounds clear again. Then adjust the low-pass filter. Do the same for the low-pass and the gain until the woofers feel just right.

Long story short, if you want to boost your bass up, you need to make sure that the gain is set down. That’s the magic trick to get a kicking bass without any distortion.


Why Should I Get Amplifiers in My Car?

Reasons to get car amps

The main benefits of getting an amplifier are pretty much known by everyone. An amp enhances the audio quality of the music that your head unit plays. But, that’s not all. There are a handful of other benefits of getting a car amplifier. Here they are:

Canceling Out Noises and Distortion

An amplifier enhances the sound delivered by your speakers by blocking out the noise and clearing the distortion created by the machinery of the sound system.

Then, there are the noises emitted by the different components inside the car and the road itself. A car amp blocks out all these noises so that you get a crisp and clear audio output.

An amplifier also comes with increased headroom for your audio system. The ability of an audio system to play sudden blasts of music effortlessly and with seamless power is known as headroom.

When you add an amp to your head unit, naturally, it increases the power of the speakers and this increases the total power count of your audio system.


It Improves Power Efficiency

An external amplifier improves the power efficiency of your car’s head unit, which in turn cuts down the fuel usage of your car.

The more high-end the amp is, the better it will be at delivering more power by using less fuel. It might cost more at first, but soon the saved amount of fuel will make up for the extra money you paid to get yourself a quality amp.


My Last Two Cents on the Topic

A car amp increases the lifetime of your car’s audio system by putting less stress on the head unit to draw more power. It enhances the audio quality of your car’s sound system.

Also, it helps you save fuel, money, and well, the planet by using up less fuel. Getting a quality amplifier for your car can be a great investment if you do your research and give it enough thought. We hope this article helps with the process.