Car audio systems are complex electronic systems that play over-the-air radio, CDs, iPods and other digital music sources. They consist of three main components: the head unit, amplifier and speakers.
The head unit’s preamp takes an audio signal and preps it for the power amplifier. The amp then boosts the signal to drive the speakers, producing sound.
Head Unit
If you’re looking to upgrade your car audio system, replacing the head unit is a great place to start. Also known as a stereo, dash stereo, deck, or in-dash radio, the head unit is the central piece of hardware that provides a unified interface with screens and buttons for numerous integrated information and entertainment functions.
The head unit receives audio signals from a variety of sources, including FM/AM radio, auxiliary inputs, and even a mobile phone using Bluetooth technology for hands-free calling. The head unit also controls a speaker array to create stereo sound. It often features an advanced touch screen to navigate the various menus and controls, as well as an integrated GPS navigation system.
A head unit is sometimes confused with a receiver, although they are two different pieces of equipment. A receiver typically includes a built-in amplifier to power the speakers, which is a significant difference in terms of sound quality. A basic head unit may also include a radio tuner, but most modern models are capable of playing CDs, MP3 files, and other digital music data. Some even control remotely mounted CD changers to increase the number of available songs.
Amplifiers enhance the audio signal from the head unit and drive the speakers to produce the sound we hear when listening to our favorite tunes. Many factory-installed systems combine the head unit and amp into a single, all-in-one component to save space, but there are also many standalone amps to choose from.
Speakers are the final component of a basic car audio system and are responsible for reproducing the music we listen to. They convert the electrical audio signal from the head unit into mechanical movement, which causes the paper cones to vibrate and displace air in the cabin to generate sound waves that we hear.
Speakers vary in size, shape and form factor to cover the entire range of sound frequencies that can be heard in a vehicle’s cabin. Most systems use “full-range” speakers that combine the duties of woofers, tweeters and midrange in order to save on cost and space, but upgrades are quite common to replace these with discrete components that cover each frequency range separately. In addition, it’s important to ensure that the cabin of a vehicle is properly sound-deadened in order to maximize clarity.
Amplifier
The amplifier is the heart of a car audio system. It takes the low-level signal coming from a factory or aftermarket head unit and boosts it to a higher level that can power speakers and create sound. This is also the key to getting that loud sound most people crave.
Factory in-dash receivers typically have no more than 10 watts of maximum output per channel, and they tend to distort very quickly at high volume. A separate amplifier will provide more power and significantly improve the quality of the sound produced by the speaker system.
A standard head unit can have up to six channels, and there are several different amp configurations available that work best with various speaker setups. Some have features like built-in crossover functions, variable filters and bass boost that are designed to take your music to the next level.
The first thing most people notice when they upgrade their car audio system with a new amp is the improvement in overall sound clarity and quality. A good amp can make even a set of stock or aftermarket speakers sound much better, and it is the main way to get the loud, full-range sound most listeners want from their stereos.
A good amplifier can make a huge difference in your listening enjoyment, and it’s easy to choose the right one for your system with some simple research. When choosing an amp, look for the CEA (Consumer Electronics Association) rating on the product label. This is a voluntary standard that ensures that the product meets a minimum performance level and won’t cause excessive distortion at high volumes.
Amplifiers can also help prevent a common but annoying installation problem known as ground loop noise. This occurs when the ground wires from the amplifier touch each other, creating a low-frequency rumble that sounds terrible and can be distracting at high volume levels. Using an amp with the proper grounding can eliminate this issue, and it is important to install a good quality one if you plan to install an aftermarket system in your vehicle.
Speakers
As the name implies, speakers are the final element that turns an electronic audio signal into something we can hear. Speakers vibrate and push air molecules back and forth to create sound waves. These waveforms contain all the information necessary to reproduce a particular tone.
Car stereos can play many different frequencies, but to hear them at their best, we need speakers with the right frequency response. The most common type of factory-installed speakers are coaxial, which have a woofer and a tweeter mounted on the same axis. Higher-end systems often include component speakers that are physically separated, allowing for more precise tuning and a better sound quality.
The first component in a car audio system is the head unit, sometimes also referred to as a radio or stereo, although those are inaccurate terms that don’t tell the whole story. The head unit produces an audio signal from one of many data carriers — 8-tracks, cassette tapes, CDs, digital music files, or even your smartphone’s Bluetooth connection — and sends it to the amplifier and speakers.
A head unit’s most important function is to provide a clear, undistorted audio signal. But without an amp, that signal would be too weak to physically move the speakers and create sound. That’s why the simplest car audio systems have both an amp and a head unit.
An amp’s job is to increase the strength of the signal, allowing it to drive speakers and reproduce sounds at higher volumes. Amps also have features that can help improve sound quality, such as a high-pass filter that removes low bass frequencies from the output of your speakers.
When your car’s original speakers are too full of bass, it can distort the music you’re listening to, making it less crisp and clear. It’s easy to solve this problem by installing a high-pass filter that filters out low-frequency frequencies before they reach the speakers. Experimenting with the gain control on your car’s amplifier can also make a big difference. Most people think the gain control adjusts the volume, but it actually changes how much signal the amplifier passes to the speakers.
Wiring
While the head unit and amplifier are the most important parts of any car audio system, the wiring in a vehicle is equally as vital. Choosing and connecting wires correctly is the key to achieving great-sounding music that will last for years.
Most cars come with a factory-installed head unit that provides an audio signal for the radio, CD player or other source. This component is commonly referred to as a “radio” or “stereo,” but the term is misleading as it does not include the fact that these units can play many types of audio sources, including 8-tracks, compact cassettes and digital media.
The first component in a car audio system is a preamp, which takes the low-level audio signal from a head unit and prepares it for the power amplifier. This process includes slightly boosting the signal to make it compatible with the amp, which will then significantly increase its strength to move the speakers and create sound.
Because space is limited in a car, most factory head units have their own low-power amplifier built into them. However, this limits the number and size of speakers that can be run with the system, as well as its potential volume. Upgrading the head unit with a newer model can improve the quality of the sound, but replacing the factory-installed speakers will offer a significant improvement in the overall listening experience.
The last component of any car audio system is the speaker, which turns electrical energy into mechanical energy that vibrates a speaker cone back and forth. This motion displaces air and creates sound waves that we hear. The speaker’s design determines the frequency range of sounds it can produce, and many systems will include a subwoofer to deliver the lowest tones, known as bass.
When choosing an amp and speakers for your car audio system, it is essential to know the voltage rating of your source unit and battery. Voltage ratings will affect how much current is drawn from the battery and what the maximum power output of your amplifier can be. Understanding how watts, volts and ohms work will help you understand how the components in your system interact to create the best sound possible.