Car audio systems have come a long way since Galvin manufacturing introduced the "Motorola" in 1930 and revolutionized the industry. Since that time companies and hobbyists alike have continued to push boundaries for motorists listening pleasure.
We have seen tube transistor radios, 8-tracks, cassette decks, cd players, mp3 players, and now Bluetooth. Despite these innovations and leaps forward in decibel level and clarity, the fact remains that any car audio system consists of 3 main components. Strip away all the bells and whistles and you are left with 3 fairly simple parts.
The head unit is essentially the brain of the entire system. If we were talking about a car it would be the driver. The head controls audio input, volume and parametric values such as panning and EQ. When you fire up your Backstreet Boys playlist on Spotify, the head is what receives your signal then sends it to the other components and tells them what to do with it.
Some head units have settings that can control lighting and visuals on screen as well as many other bells and whistles. Much like a car without a driver, a stereo without a head simply won't get you very far.
Going back to our car analogy, the amplifier would be the engine. The amplifier takes a previously inaudible signal and puts more power behind it. This is achieved using what is called a step-up power supply.
A series of capacitors and resistors make the audio signal stronger so that it can vibrate the cones of the speakers. When you crank the volume on your head, it is much like stepping on the gas. You're telling your engine to give you more power, which in turn makes the speakers vibrate more which makes the signal louder.
If the head is the driver and the amplifier is the engine, then the speakers must be the wheels. This is where you can see (or hear in this instance)the whole thing in motion. The speakers work by taking this amplified electrical signal and run it through what is called a voice coil that is attached to the sound cone.
A magnet fixed in place behind the coil causes the coil to either attract or repel. This creates the vibration then the vibration puts the sweet, sweet sounds of Britney Spears in your ear. Stock systems typically come with three types of speaker drivers. Tweeters for high frequency (shredding guitar solos), Mid-range (for them soulful vocals) and woofer (all about that bass). Of course, you can add super tweeters and subwoofers to achieve an even further depth of sound and that bone-rattling bass.
Pro audio in cars has come a long way and will continue to innovate in the years to come. But no matter what some slick-talking salesman has to say, you are now equipped with the fundamentals of a car audio system. Now go forth, and share your newfound knowledge with the world.