Terms and Definitions
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. It 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 doesn’t include a radio tuner.Mechless: A digital media receiver or head unit—one that does not have mechanized controls.
Car Stereos and Head Units
A head unit is the brain of your car’s sound system. It may refer to or include various devices, including radio tuners, CD players, auxiliary inputs, and built-in components such as amplifiers and equalizers. A car stereo is more general, as it includes the head unit and 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. Some receivers and tuners 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 don’t. 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 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 a 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:
CD players DVD players Digital music players and DACs USB inputs Bluetooth connectivity Video screens
Choosing the Right Head Unit
If you’re concerned about choosing the right head unit, it will be helpful to understand these terms. For example, if you’re taking a piecemeal approach to building your car stereo, you may want a receiver that includes built-in preamp outputs. This allows you to keep your options open until you decide whether to install an external amplifier. In any case, remember that these terms sometimes overlap or are used interchangeably. Understanding the differences between them can provide a blueprint for your car’s sound system.
