Car Audio 101

So you like music.  And you have a car.  And you think you would like to upgrade the stereo in your vehicle to make it more enjoyable.  But you really don't have any understanding of how car stereos work, or what you could do to make yours better.

Sound like you?  If so, you've come to the right place.

The goal of this part of the website is to educate our customers and help them learn the basics so that they can make educated decisions when it comes time to purchase.  In car audio 101, nothing is assumed.  We will be starting with the very basics.  So without further delay, let class begin.

The parts of a stereo

Car stereos can generally be split up into three different parts.  First we have the head unit, which is where the music signal originates.  This could be a CD player, an FM radio, or a long list of other possible sources. 

The second part of a stereo system is the amplifier.  The amplifier(s) take the music signal coming from the source unit and amplify it, boosting its power.  In a basic stereo system, this can often occur inside of the head unit, but does not necessarily have to.  In a larger, higher quality stereo system the amplifiers are a seperate unit. 

The final piece of a car audio system is the speakers.  There are many types of speakers, ranging widely in both function and size.  The speakers in the stereo system take the electrical power coming from the amplifier and turn it into sound.

It can be accurately said that your stereo system is only as strong as the weakest link.  If you have an amazing amplifier but your speakers are poor quality, the overall sound is going to be bad.  Or say you have a great source unit and top notch speakers, the end result can still be very poor if your amplifier is not up to par. 

With this in mind, lets dig in to each component a little deeper and learn more about what they do, and how they do it.

The Head Unit

The head unit is where it all starts.  This is  the component that allows the driver to select what type of music they would like to listen to, and also how loud they would like to listen to it.  Adjustments to the sound (such as turning up the treble, or adjusting the bass) are typically, but not always, done here also.  This unit is almost always installed in the dash of the vehicle, within easy reach of the driver.  They typically have a display screen that tells you basic information such as the track number of the CD you are listening to, or the frequency of the radio station you are currently tuned in to.  On more advanced head units the display is able to give even more information, such as the name of the song or artist.  Units are even available that, in conjunction with a GPS signal, can give you driving directions, your rate of speed, elevation, and more.

In the past few years the options and features on head units have expanded immensely.  Not long ago you could choose between your CD collection, or AM/FM radio, and that was about it.  Now, options include sattelite radio, aux or USB inputs that you can plug your iPod into, and Bluetooth audio that allows you to wirelessly stream music or talk on the phone.  In addition, features that were once only found on aftermarket replacement radios are now becoming available as standard equipment in new vehicles.  This is causing an increasing number of people to choose to retain their factory radio, as opposed to replacing it with an aftermarket unit.  More on that later.  For now, lets focus more on what features you should be looking for, what matters, and what doesn't.

When it comes to picking what head unit (or any other component of your audio system) is right for you, don't let someone try and tell you what you want.  Its your vehicle, and only you know for certain what you really want out of it.  I get asked all the time "which one would you get?".  My answer to this question is always the same.  It doesn't matter what I would want at all, lets focus on what YOU want.  What is your budget?  Do you own an Ipod?  If so, would you like to be able to charge it while listening to music in your car?  Do you plan on adding additional amplifiers to the system?  Do you want a unit where the display changes colors, or is a single color fine for you?  Would you like to be able to do hands free calling in your vehicle, allowing your to talk on your cell phone while you drive?  What other components do you hope to add to your stereo now, or in the future?  What kind of goals do you have in regards to sound quality, and overall output?  These are all questions that need to be answered before you can really determine the best head unit for you. 

The Amplifier

The music originates in the head unit and the audio signal is then sent to the amplifier.  In most basic stereo systems this entire process occurrs inside of the head unit itself.  Most head units have small amplifiers inside of them, producing anywhere between 5 to 15 watts per channel.  This is how many factory and aftermarket head units work.  However, in a more advanced stereo system, the amplifier inside of the head unit is not used.  Instead, the audio signal is sent to a larger, more powerful external amplifier, usually (but now always) installed in the trunk or rear of the vehicle.

Adding an external amplifier has many advantages.  The largest advantage is the fact that an external amplifier is going to produce significantly more power.  With more power coming from the amplifier, the speakers are going to be able to play much louder.  As stated previously, an average head unit usually puts out somewhere between 5 and 15 watts per channel.  Some external amplifiers on the other hand are capable of producing literally thousands of watts.  This is obviously a massive difference.  Even an amplifier that produces 50 or 100 watts is going to allow the speakers to play much louder.

Another advantage of adding an external amplifier is that they are typically able to generate a much cleaner, clearer electrical signal going to the speakers.  This gives the stereo system a significant improvement in sound quality.  The sound coming from the speakers is going to be more accurate, and more closely resemble the sound that was originally recorded onto the CD (or iPod, or Radio, etc.).  Typically the amplifier inside of a head unit is designed with cost in mind, and as such the quality suffers greatly.  In a head unit, once the amplifier reaches its maximum capable output it begins distorting quickly.  When this happens, the sound quality of the system degrades significantly.  With an external amplifier, this distortion point is not reached as quickly, allowing you to turn up the volume further without ill effect.  The final advantage of adding an external amplifier is being able to use a crossover, which splits up the different audio frequencies going to each speaker.  This is a more advanced topic, and will be discussed further in Car Audio 201.

The Speakers

The speakers are the component that takes the electrical signal from the amplifier and turn it into sound.

Did you know?

We are typically taught that electrical current flows from positive to negative.  In fact, this is what Benjamin Franklin first postulated in the 1750s when he did his famous "kite experiment".  However, a Physicist in the late 1800s discovered that electricity is actually caused by the flow of electrons, and that electrons have a negative charge.  What does this mean?  Essentially, good 'ol Mr. Franklin guessed, and he guessed wrong.  Electrical current (electrons) actually flows from negative to positive.