What Is a Head Unit Versus a Car Stereo, Receiver or Tuner?

driver using the car audio stereo system

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Audio, in general, is a complex and convoluted subject. The same is true when it applies to your car. One such topic of confusion is the difference between car radios, car stereos, head units, and receivers.

Here’s a basic rundown of the most common terms and definitions associated with car audio:

  • Head unit: Any in-dash car stereo control unit.
  • Car stereo: The entire sound system in a vehicle—includes both head units and speaker systems.
  • Receiver: A specific type of head unit that features a built-in amplifier.
  • Tuner: Another term for a head unit—usually one without a built-in amplifier, and usually referencing the radio.
  • Car radio: Catch-all term that refers to both receivers and tuners.
  • Controller: A type of head unit that does not include a radio tuner.
  • Mechless: A digital media receiver or head unit, i.e. one that does not have mechanized controls.

Car Stereos and Head Units

A head unit is essentially the brain of your car's sound system, and it may refer to or include a range of different devices, including radio tuners, CD players, auxiliary inputs, and built-in components like amplifiers and equalizers.

A car stereo is more general, as it includes the head unit as well as the speaker system, including amplifiers, equalizers, crossovers, speakers, and subwoofers. The term "car stereo" is often used synonymously with "head unit."

Receivers, Tuners, and Car Radios

Two closely related types of head units are receivers and tuners. Both include a built-in AM/FM radio tuner. For that reason, receivers and tuners are also often referred to as car radios. Many receivers and tuners may also include CD players, auxiliary inputs, Bluetooth connectivity, and USB ports, but that varies from one model to the next.

Where receivers include built-in amps, tuners do not. Most factory head units are receivers because it is more expensive to build a system with an external amplifier, although there are some exceptions. The majority of aftermarket head units are also receivers, although tuners are also available for people who are interested in adding an external amp and getting the best sound quality possible.

Some receivers include preamp outputs. That means that although the head unit has a built-in amp it also has audio outputs that bypass the amp. These head units are great for anyone who is building their system piece by piece; you can rely on the built-in amp until you get around to installing an external one.

Controllers

Head units that do not have radio functionality are usually called controllers. These head units may or may not have built-in amplifiers, and they may feature a range of components, including:

Choosing the Right Head Unit

If you’re concerned about choosing the right head unit, then it will be helpful to understand these terms. If you’re taking a piecemeal approach to building your car stereo, for example, you may want a receiver that includes built-in preamp outputs. This will allow you to keep your options open until you decide whether to install an external amplifier.

In any case, it’s important to remember that these terms sometimes overlap or are used interchangeably. Nonetheless, understanding the differences between them can help provide a blueprint for your car's sound system.