Senin, 11 Agustus 2008

what is car audio ??

CAR AUDIO

Car audio/video is a term used to describe the sound and video system fitted in an automobile.

A stock car audio system refers to one that was specified by the manufacturer when the car was built. A custom car audio installation can involve anything from the upgrade of the radio to a full-blown customization of a car based around its audio equipment. Events are held where entrants compete for the loudest or most innovative systems.

The most common and familiar piece of audio equipment is the radio/tape player/CD player/DVD Player which is generically described as a Head unit, which also can be called a head deck, after older tape decks. It is also the most likely component to be upgraded with an after market item. A recent development in head unit technology has been the addition of CD players with MP3, Ogg, WMA, AAC, and USB, Bluetooth and Wi-Fi support. Even with the rampant ubiquity of solid state MP3 players, car audio systems with line-in jacks and other standards are only in their infancy, and that since tape adaptors are often used with tape players, people are now viewing car radios with built-in CD players as "misfeatures" of the audio system since people now often "rip" their CDs onto their computers.Other types include the video touch screen capable of controlling; navigation, dvd movies, mp3 players back up camera and other accessories.

Most modern cars include at least a CD player/ CD recorder, and some have the option for a CD changer, which holds multiple discs either in the head unit itself or in a separate unit usually located in a trunk or console.

More recent is the addition of DVD players and LCD screens. Depending on the head unit, the LCD screen is either integrated such that it slides out and folds up, or integrated into the instrument console. Otherwise, the DVD head unit feeds video output into separately mounted displays, either folding down from the roof, or mounted into the headrest for viewing by rear seat passengers.

The video screen may also show video output of an integrated component such as a navigation system, 3G cell phone or parking cameras that could be automatically activated when the car is put into reverse.
A set of speaker drivers removed from a passenger vehicle.
A set of speaker drivers removed from a passenger vehicle.

Car speakers are generally located in doors and rear parcel shelves of a sedan in modern cars. High-end or competition stereo systems often have speakers mounted in "kick panel" enclosures, allowing for larger drivers and better driver placement. Before stereo radio was introduced, the most common speaker location was in the middle of the dashboard pointing through perforations towards the front windshield.

High-end audio systems include Component Speakers that consist of a matched tweeter (small, high frequency), midrange (medium, medium frequency) and woofer (large, low frequency) set. These component pairs are available in two speaker and three speaker combinations, and include an audio crossover which limits the frequency range that each component speaker must handle. This allows each cone to produce its optimal frequency for maximum sound quality and volume. In addition subwoofer(s) are provided for bass and sub bass (ultra low frequency), which is felt more than heard depending on the sub frequency, the lower the frequency the less the human ear picks it up, however the chance of "feeling" the vibration becomes greater. Sub bass is omni-directional, meaning that the human ear cannot distinguish where the sound is coming from. Humans can not hear subsonic frequencies (below the frequency of 20hz), we are however able to feel it (eg. An air rush when closing a door cannot be heard, it can be felt however). Crossover systems can be active or passive crossover networks. Active electronic crossovers divide the signals before they are sent to the amplifiers giving a dedicated amplifier channel to each individual driver in the component system. Passive crossover networks divide the signal after amplification, making it possible to run multiple speaker component sets using just one channel.

5.1 and even 7.1 channel surround sound systems, as well as THX II Certified, are now being integrated into some cars by both aftermarket enthusiasts and car manufacturers themselves. These systems include the full complement of front left, right and center speakers along with rear right and left surround speakers (7.1 systems include left and right side surround speakers) along with digital surround sound processors. They can allow you to turn your car into a virtual rolling theater. This is becoming increasingly popular with the advent of SACD and DVD Audio which contain music encoded in 5.1.

4Ω is the most commonly used impedance in car loudspeakers.

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