Most people use the term car audio to describe the sound system in an automobile, though the term also refers more broadly to the field of mobile entertainment and is becoming a sport at large. A stock car audio system refers to exactly what was specified by the manufacturer when the car was built. A custom car audio installation could mean anything from the upgrade of the radio to a full-blown customization of a car based around delivering exceptional sound quality or volume from audio equipment.

The most common and familiar piece of audio equipment is the radio/tape player/CD player which is generically described as a Head unit, which also can be called a 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, WMA, AAC, and USB support.

Many cars include at least a CD player some have the option for a CD changer which holds multiple disks either in the head unit itself or in a separate unit usually located in a trunk or console. Our horizons have been broadend even further-even newer technology is the addition of DVD players. The position of the LCD screen differs for different DVD players - certain DVD players require the screen to be mounted on the roof of the car (just above the front windscreen), while others require the screen to be attached to the back of the headrests of the front seats and some DVD players have the screens come out of the head unit.

Speakers are generally located in doors and rear parcel shelves of a sedan in modern cars. 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, rather than heard.

Amplifiers provide the necessary music power, measured in watts to drive the speakers. High Power amplifiers require a large gauge cable to provide adequate voltage and current to the amplifier. The amlifier is a very important component of a loud speaker system. Connecting too many speakers to the head unit alone. (Make sure that the total power of the speakers connected to the amplifier or even the head unit for that matter is less than or equal to the power handling capacity of the amplifier/head unit)

Sound deadening is often used in the door cavities and boot/trunk area to provide less rattling of the metal in the car, especially the boot/trunk, and to help produce a cleaner sound by absorbing instead of reflecting sound waves. It is a rubber or asphalt-like substance that can be sprayed on or glued on in sheets.

Alternators may be upgraded from the stock unit to increase the current capability of the vehicle's electrical system, often required of high-power audio system components. An additional Deep Cycle battery (or, for very large systems, banks of batteries) can be deployed (often charged via a Split charge relay) to limit voltage drop and allow the system to be played for long periods without the vehicle's engine being run. Installing a capacitor is another option when trying to provide substancial power to the audio system.

Other components that make up high end car audio installations may include:

• amplifiers
• audio processors
• cables
• crossovers
• equalizers
• mobile video (VCRs, television, DVD and navigation)
• stiffening capacitors

Common modifications in high end car audio installations:

• amp racks
• speaker pods
• subwoofer enclosures

History

The introduction of the car stereo came in the 1930s from the Galvin Manufacturing Corporation. Galvin Manufacturing was owned and operated by Paul V. Galvin and his brother Joseph E. Galvin. The Galvin brothers purchased a battery eliminator business in 1928 and the corporation’s first product was a battery eliminator that allowed battery-powered radios to run on standard household electric current. In 1930, the Galvin Corporation introduced the first commercial car radio, the Motorola model 5T71, which sold for between $110 and $130 and could be installed in most popular automobiles. The name Motorola was created by Paul Galvin combining the term “motor” for motion and “ola” for sound [1].

The movement to add more than just a basic radio to a car largely originated on the west coast of the United States in the late 1970s. Several early manufacturers and enthusiasts began building audio amplifiers to run on twelve volts (the standard voltage in automotive electrical systems). Jim Fosgate, later to become the founder of Rockford Fosgate, was one such pioneer. The company a/d/s also brought an amplifier to market in 1978.

At first, speakers from the home audio and professional markets were simply installed into vehicles. However, they were not well suited to the extremes of temperature and vibration which are a normal part of the environment of an automobile. Modified drivers were developed to cope with these factors.

Today, advances in acoustic technology mean that even two 10-inch speakers in a well-designed efficient enclosure can produce more than 160 decibels SPL (sound pressure level) within the cabin.

Car audio competitions started in the early 1980s in a quest to find the loudest and/or most outrageous installations. For example, in 1985, Wayne Harris famously modified a 1960 Cadillac Hearse to feature several 24-inch subwoofers. Little consideration was given to sound quality early on, but in the early 1990s, several organizations, including IASCA, began car audio competitions focusing on sound quality. The two styles -- SPL vs. sound quality -- have become almost mutually exclusive.

Notable Installation Schools

• Mobile Dynamics
• Mobile Technical Training
• RITOP Installation School

See also

• DB drag racing

Notable Installations

• The SpeakerWorks/USD Audio Buick
• Wayne Harris' Hearse
• Steve Brown's M3
• Steve Cornell's Impala SS
• Earl Zausmer's BMW
• Gary Bigg's Buick Regal
• Mark Eldridge's 4Runner

Manufacturers and brands

• a/d/s
• Adire
• Alpine
• Arc Audio
• Ascendant Audio
• Audiobahn
• Blaupunkt
• Bose
• Boston Acoustics
• CDT audio
• Celestra
• Clarion
• Coral Electronic
• Diablo Audio
• Diamond Audio
• Digital Designs
• DLS
• Eclipse
• Elemental Designs
• Focal
• Fusion
• Genesis Amplifiers
• Harman Kardon
• Infinity
• JBL
• JL Audio
• Kenwood
• Kicker
• Ma Audio
• Magnat
• McIntosh
• Memphis Car Audio
• Milbert Amplifiers
• Morel
• MTX Audio
• Nakamichi
• Pear Cable Audio Cables
• PHD Audiophile
• Pioneer
• Power Acoustik
• Precision Power
• Resonant Engineering
• Rockford Fosgate
• RS Audio
• Seas
• Sony
• Soundstream
• Sound Splinter
• Target Audio
• Treo Engineering
• Tru Technology
• Us Amps
• Zapco
• Zed Audio

Car Audio Links

• CarStereo.com, The online community for car audio beginners, enthusiasts and professionals.
• View some of the hottest Car Audio systems in the world.
• Elite Car Audio: An online forum offering discussion of all aspects of car audio
• Car Audio Installation Forums, Links, FAQ's, Articles
• History & Photographs of Audio Dynamics Design's enclosure factory, the first developer of exterior subwoofer enclosures.