Head unit

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A head unit is a component of a stereo system either in a vehicle or home cinema system used to tie together and provide a unified interface system for the various components of a system, ranging from audio players such as a remote-mounted CD changer, to the speakers or audio amplifiers. An antiquated name for a head unit is a receiver.

In vehicle applications the "headunit" is widely considered the center piece of the vehicle's sound system. With the wide array of options from one manufacturer to another it's hard to list every available feature. Most commonly "headunits" give the user control over the vehicle's media such as; CD's, Mini Discs, Cassette Tapes, Mp3's, AM/FM, Satellite, Navigation, etc. They may also give the user control over functions such as Volume, Band, Frequency, Speaker Balance, Speaker fade, EQ functions and many more depending on the manufacturer. Several OEM manufacturers such as General Motors are integrating computer systems into vehicle's "headunits" these "headunits" control functions such as door chimes and offer vehicle data such as trouble warnings and odometer information. Now more than ever the "headunit" is as much an aesthetic addition to a vehicle as it is Functional. Many consumer's look for a "headunit" with great looks as well as great features. With the addition of Satellite radio and Mobile Navigation it is increasingly common to see "Headunits" with video monitors built in to them.

The most standard sizes in vehicles are Single DIN ISO 7735 (178x53mm) in Europe, South America and Australasia and Double DIN (178x106mm) in Japan and North America.

[edit] Connecting to the electrical system

ISO 10487 connector in car, fits into head unit

The 8-pin ISO 10487 connector typically used in head units contains pins for power-supply, off/on (typically controlled by ignition key), speakers and optionally motorised antenna.

Pinouts viewed from the cable side of the female connector: