Car music and entertainment has come a long way since 1930, when Motorola introduced the first commercially successful car radio, the Model 5T71. Today from just being radio car music systems they match up to any full fledged music system with plenty of options like radio, CD, portable music players like the iPod, USB flash drives, SD cards, Bluetooth audio and hard-disk drives.
However no matter what the technological advancements are, every car music and entertainment still has the same basic structure of three main components. The first is the radio or also known as the 'head unit' that controls the entire system and generates the audio signal. The second is an amplifier that controls the level of music and finally the output which is the speakers that reproduce the sound.
The Head Unit
Unlike other normal music players, car music and entertainment systems have to fit in a tight space and sometimes double up as the overall system volume and also amplify the various audio sources in a vehicle. Today Head units allow you to control the iPod or navigate the content of a USB flash drive. You also have the option of Bluetooth audio that allows you to listen to stuff from a compatible mobile phone. You can also choose from a wide range of music options like bass, treble ambience setting etc.
Amplifier is to increase the power of an audio signal and make sure that it gives you the required buzz to keep you entertained. The preamp is usually housed inside the head unit and takes data from a radio, CD player or other audio source and prepares it for the power amplifier. The pre amp ensures that it is resistant to noise and other external interferences. The power amplifier then takes the signals from the preamp and boosts it to the speakers to give you the sound effect.
Speakers receive the amplified electrical signal and convert it into mechanical energy that moves the speaker cone back and forth to create sound. Sound is nothing but vibrations in the air and a speaker cone creates these vibrations. So any vibrations in the human hearing range of 20 hertz to 20,000 Hz can start to enjoy the music.
The most basic automotive speakers are designed to be 'full range' to cover the entire frequency range. However with one speaker it is not possible to get the entire effect. You can get the exact sound effect like bass, treble, surround, echo with an assortment of speakers dedicated to reproducing a smaller range of sound.