Vehicle audio
Vehicle audio is equipment installed in a car or other vehicle to provide in-car entertainment and information for the occupants. Until the 1950s, it consisted of a simple AM radio. Additions since then have included FM radio (1952), 8-track tape players, cassette players, record players, CD players, DVD players, Blu-ray players, navigation systems, Bluetooth telephone integration, and smartphone controllers like CarPlay and Android Auto. Once controlled from the dashboard with a few buttons, they can be controlled by steering wheel controls and voice commands.
"Car radio" redirects here. For the Twenty One Pilots song, see Car Radio (song).Initially implemented for listening to music and radio, vehicle audio is now part of car telematics, telecommunication, in-vehicle security, handsfree calling, navigation, and remote diagnostics systems. The same loudspeakers may also be used to minimize road and engine noise with active noise control, or they may be used to augment engine sounds, for example, making a small engine sound bigger.
The stock system is the OEM application that the vehicle's manufacturer specified to be installed when the car was built.
Aftermarket components can also be used.
Amplifiers increase the power level of audio signals. Some head units have built-in stereo amplifiers. Other car audio systems use a separate stand-alone amplifier. Every amplifier has a rated power level sometimes noted on the head unit with the built-in amplifier, or on the label of a stand-alone unit.
Legality[edit]
Excessively loud sound systems in automobiles violate the noise ordinance of municipalities, some of which have outlawed them.[35] In 2002, the U.S. Department of Justice issued a guide to police officers on how to deal with problems associated with loud audio systems in cars.[36]
A 1950s Philips car radio using both transistor and valves. This model used a range of valves that only required 12 volts for their plate (anode) voltage.[37]
![A 1950s Philips car radio using both transistor and valves. This model used a range of valves that only required 12 volts for their plate (anode) voltage.[37]](http://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Autoradio_Roehre.jpg/120px-Autoradio_Roehre.jpg)
GM Delco Transistorized "Hybrid" (vacuum tubes and transistors), first offered as an option on the 1956 Chevrolet Corvette car models
A car stereo head unit in a dashboard
1942 Lincoln Continental Cabriolet radio
Dashboard of VW Hebmüller with Telefunken Radio (1949/50)
Blaupunkt Köln Radio - German 1958 Ford Taunus 17M P2 deLuxe
1990 Ford Sierra CLX Radio-Cassette head unit in a dashboard with cassette storage
A set of speaker drivers removed from a passenger vehicle
A car audio amplifier
Two 10-inch subwoofers in the trunk of a car
As technology keeps evolving, head units are now paired with the climate control system and other functions
An example of the evolution: 2010's Volkswagen has a smart panel both with buttons and a touch screen to play radio.
