Car Stereo Glossary
Click on a letter below to jump to that section of the glossary.
- Detachable Face — Lets you remove the control panel of your receiver easily, and take it with you when you leave the car. The stereo is useless to thieves without the faceplate, so the temptation to break in your car is greatly reduced. All but a handful of the receivers we offer come with a detachable face.
- Security Code Some stereos give you the option of setting up a security code. This is usually in addition to having a detachable faceplate. The security code is a three or four button combination, usually using the radio preset buttons, that has to be entered before the stereo will function.
An input on the face or rear of the receiver that enables you to connect a plug-and-play satellite radio tuner or portable music player (CD, MP3, or cassette) to the receiver. The input jack can be either Mini or RCA.
On May 28, 2003, the Consumer Electronics Association published standard CEA-2006, "Testing & Measurement Methods for Mobile Audio Amplifiers." This "voluntary" standard advocates a uniform method for determining an amplifier's RMS power and signal-to-noise ratio.
Using 14.4 volts, RMS watts are measured into a 4-ohm impedance load at 1 percent Total Harmonic Distortion (THD) plus noise, at a frequency range (for general purpose amplifiers) of 20 Hz to 20,000 Hz. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. This applies to both external amplifiers and the amplifiers within in-dash receivers.
CEA-2006 allows consumers to be able to compare car amplifiers and receivers on an equal basis. Manufacturers who choose to abide by the new standard are able to stamp their products with the CEA-2006 logo that reads: "Amplifier Power Standard CEA-2006 Compliant."
Originally, changer controls referred to a receiver's ability to control a same-brand CD changer. These days, the changer control connection on a receiver can be used to add one of any number of peripheral devices. Most stereo brands let you choose from a CD changer, satellite radio, iPod® adapter, USB adapter, Bluetooth™ adapter, and more.
A codec is a method of compressing and decompressing digitized sound. MP3 and WMA are examples of different codecs. In the standard CD audio format, one minute of music takes up roughly 10 megabytes. When converted to MP3, that same minute of music takes up only about 1 megabyte.
Digital-to-Analog (D/A) Converter
Your CD receiver uses a D/A converter to convert digital 1s and 0s back into analog audio signals. CDs store audio data in binary, digital form. This digital data is an accurate, noise-free reproduction of recorded signals, but in digital form it doesn't sound like music to your ears. The D/A converter translates the digital info back into music — that's why it's so important to your CD receiver's performance.
Digital Media Files
Music which has been subjected to data compression — allowing users to store many hours of music as computer files. A growing number of in-dash CD receivers have the ability to decode and play recordable CDs (CD-Rs and CD-RWs) loaded with MP3, WMA, AAC, or WAV files. A single disc can hold up to ten hours of music.
Digital Media Receiver
Digital media receivers are in-dash receivers that do not have CD players built in. Instead, they feature multiple inputs for devices like iPods, USB drives, SD cards, and so on.
- DIN A "Euro DIN" receiver (or "E" fit) is the most common size of receiver for automotive applications. It has a rectangular chassis that measures about 7" wide by 2" tall (depths vary), and loads into the mounting surface from the front. DIN-size receivers slide into a metal or plastic sleeve that attaches to the front of the mounting location.
- ISO-DIN The "I" and "J" fits are essentially the same dimensions as the DIN receivers, but they do not mount through the mounting sleeve. Instead, they attach directly to the side support system of the factory receiver location.
- Double DIN So-called "double DIN" receivers are two times the height of DIN-size receivers,which typically works out to 4" tall. These receivers are also shallower in depth and slightly wider. In many cases, these receivers re also equipped with DVD players and navigation systems.
- Fold-down Face — Slot-faced receivers are convenient, but their displays are smaller out of necessity. A fold-down face, on the other hand, hides the CD slot behind the control panel, and allows the receiver to include a larger display for greater legibility. Hiding the slot also increases the unit's reliability by reducing internal exposure to dust and dirt.
- Multicolor Display — A multicolor display improves readability and reduces the amount of time your eyes spend away from the road. Monochrome displays cannot represent different functions with unique colors, so you spend more time trying to decipher the readout.
- Backlight — A backlit display significantly improves visibility under adverse conditions. For example, if the sun is shining on your faceplate, a backlit display is easier to see.
These versatile receivers can play DVD movies, and may play DVD audio discs. Some models send the video signal to an outboard backseat monitor for on-the-go viewing, while other models include a built-in screen for stationary viewing. These receivers have digital-to-analog converters that are superior to those found in most regular CD receivers, so your CDs will usually sound better on a DVD receiver.
A built-in EQ lets you tailor the sound to your listening tastes and to your vehicle's acoustics. Receivers with built-in EQs will have one or more equalizer "bands" in addition to standard bass and treble controls. These equalizer "bands" usually have fixed center frequencies and bandwidths (although some may be adjustable).
More sophisticated built-in EQs offer parametric equalization, which allows you to set the amount (in dB) by which a certain frequency band is boosted or cut — and determine the width and/or center frequency of this band. This gives you extremely precise control of the tonal balance in your vehicle.
Preset EQ curves are stored tone settings — boosting and cutting different frequencies can make big changes in the way your music sounds. Preset EQ curves are stored in memory, and are easily activated. If you listen to a wide variety of music, these presets are useful for making dramatic tonal changes instantly. (For example, you could use one EQ preset with heavy bass boost for rap or reggae, and a second preset with flat bass and a slight midrange/treble boost for jazz. This saves you from constant readjustment of the tone controls.)
The European tuning interval of .05 MHz is different from the US tuning interval of .2 MHz. If a CD receiver also has European tuning, it is compatible with the European scale and can be used in many European countries.
FM Mono Sensitivity
This figure tells you how well a CD receiver can pick up FM radio signals. The smaller the number, the greater the ability to pick up weaker stations. Expressed in decibel femtowatts (dBf).
The range of sounds, from bass to treble, a stereo component can reproduce. It's measured in Hertz (Hz), and a wider range is better — the bass will be lower and the treble will be higher. Humans can perceive sounds from 20 to 20,000 Hz. The lowest note on a bass guitar is about 41 Hz. Most male vocalists have a range between 100 and 500 Hz. Cymbals hit at about 15,000 Hz.
GPS, which stands for Global Positioning System, is a navigational system designed and operated by the U. S. Department of Defense (DOD). If you have a navigation-equipped receiver, it processes coded satellite signals from three or more GPS satellites every second, and then calculates the vehicle's velocity and geographical location.
A ground loop occurs when any piece of equipment or any incoming wire is connected to a different ground or grounds. If your in-dash receiver and amplifier are grounded to different locations, for example, a ground loop may occur. In this situation, the multiple ground paths can, in effect, act as an antenna for interference. The interference is turned into noise, and you hear it in your system.
The term "HD Radio" is iBiquity Digital Corporation's trademarked name for their digital audio broadcasting technology, which has become the IBOC standard adopted for the United States. Because they're digital, HD Radio signals aren't subject to atmospheric interference the way current FM and AM signals are. Background crackle and hiss are eliminated. The effect is similar to the difference between CDs and vinyl records. The digital CD signal is free of the surface noise that's always present on LP playback. Like current FM and AM radio, HD Radio broadcasts are free to the public. Your only expense is the purchase of an HD Radio tuner.
Lets you hear the first few seconds of each track on a CD. Hit the button again when you hear the song you're looking for. The scanning feature will stop, and that track will continue playing.
The Crutchfield MasterSheet, a Crutchfield exclusive, is a vehicle-specific set of instructions that shows you how to remove your factory receiver (and speakers) and install a new one. Your MasterSheet is included free with your Crutchfield receiver or speaker purchase.
MP3 encoding compresses musical data, enabling users to store many hours of music as computer files. A growing number of in-dash CD receivers have the ability to decode and play recordable CDs (CD-Rs and/or CD-RWs) loaded with MP3 files. Also, portable MP3 players can be used to play these files through a car receiver's auxilary inputs. For more information about all types of file formats, visit our File Formats Glossary.
Multi-path interference affects FM radio reception. FM waves travel in a straight line, so anything between you and the FM transmitter can cause multi-path interference. When FM signals bounce off buildings and other large objects , the tuner picks up the same signal more than once, at different times. This create "echoes" that confuse the tuner by mixing with the original signal.
A typical in-dash navigation system consists of a car stereo with a built-in monitor (ranging from 6-1/2" to 7"), an external GPS antenna, and sometimes a hideaway connection box that contains the A/V inputs and outputs. The stereo mounts in the factory stereo slot in your dash. The hideaway box is usually mounted behind the dash or under a front seat. In addition to CD playback and AM/FM reception, most in-dash systems include DVD playback, so you can watch a movie on the built-in screen when the car is parked. Installation of an in-dash system can be complex, as they require connection to power, ground, the vehicle speed sensor, and the parking brake. If your car has a single-DIN or even an old-school shaft style receiver opening, you can always use a portable GPS navigation system.
For more information on nav systems, see our Navigation Glossary.
Outfit My Carsm
Crutchfield's Research Team has compiled the world's largest car audio fit database, with over 17,000 entries. Identify your vehicle, and you'll see:
- your customized shopping homepage
- audio/video gear that's right for your vehicle
- the installation accessories you'll need
For more information about the Outfit My Car tool, check out this informative video. In it, you'll learn how you can create a custom homepage for your car on Crutchfield's website and use it to put together a complete car audio system.
Peak power is measured during a brief musical burst, such as a sudden drum accent. Some manufacturers display peak power ratings on the face of their products. The RMS power rating is more significant, and we recommend using it for comparison purposes.
Preamp outputs are jacks on the rear of a CD receiver that allow you to use a standard RCA patch cable to add an external amp. Some receivers have two sets, which help if you plan to add a 4-channel amp or a second amp. Some receivers have three sets, one of which is usually intended to be used for a subwoofer amp.
Some receivers offer a "non-fading" set of preamp outputs. Hook your subwoofer amp to the non-fading outputs, and you can fade the regular speakers front to rear without affecting the sound of the subwoofer.
Radio Data System
RDS stands for Radio Data System. RDS tuners can automatically tune in stations according to the style of music (or talk) they broadcast. Some RDS tuners can even break in with traffic alerts or emergency broadcasts when you're listening to a CD. RDS enables your receiver to display text messages (usually call letters and format info) that many FM stations include on a subcarrier signal within their normal broadcast signal.
Besides playing your musical sources (CD, radio, streaming audio, etc), the receiver has another big job: sending the audio signal to your speakers. Most receivers have built-in amplifiers, and can power speakers directly. Many receivers have pre-amp outputs, too — these send signals to an external amplifier, which boosts the signal before sending it to the speakers. For more information, see our extensive collection of receiver articles.
Here at Crutchfield, we have a vast and amazingly detailed database of information for more than 17,000 vehicles on the road today. When we research a vehicle, it’s crazy how many measurements and photos we take. We routinely use this knowledge and our expertise to help you find what fits your car when you shop with us.
But we wanted to do more, so we created the Crutchfield Research Garage. In it, we profile some of the most popular (and interesting) vehicles that visitors look up on our website. Even if your vehicle isn't on this ever-expanding list (yet), our advisors have this kind of info available when they make expert recommendations about adding car A/V gear to your specific vehicle.
Also known as shuffle play. Mixes up the order of songs during playback. Some CD players offer a "Random Play with Delete" feature that prevents a song from being repeated once it has been played.
Satellite Radio Controls
CD receivers with satellite radio controls operate SiriusXM external satellite radio tuners. A specialized antenna and service subscription are also required (in addition to the tuner) to receive the satellite radio signal.
- Preset Scan lets you push a button and automatically hear a brief sample of what's on each of your preset stations.
- Station Scan lets you sample each strong station (regardless of whether it's one of your presets) — the sampling continues until you hit the station scan button again.
- Seek tuning moves to the next strong station and stops there — you must hit the "Seek" button again to repeat the process.
This three-hole mounting system is found mainly on cars built until the early ‘80s, but can be used in almost any dash opening (mounting kit may be required). These can mount from the front or the rear.
A thumb drive, also known as a flash drive, is a small (roughly pinkie-sized) data storage device that plugs into a USB port. These tiny drives can hold a remarkable amount of information these days, which means they can also hold a remarkable number of music files. If your receiver has a USB port, you can plug it in and enjoy your tunes non-stop on a long road trip.
A processing circuit found in some receivers that compensates for the uneven distances between left and right car speakers and listeners' ears. Time correction delays signals from the closest speaker(s), so that all the sound arrives at your off-center listening position at the same time. You'll get a more accurate, lifelike stereo image.
Travel Presets or Best Tuning Memory
Engage this feature and the CD receiver automatically loads a bank of your presets with the strongest available signals. It makes finding stations easier when you're driving through unfamiliar territory. It also makes loading presets a snap when you first install the receiver or any time your battery runs down or gets disconnected (which wipes out the tuner's preset memory). Some receivers use a bank or two of your regular station presets for storage; others have dedicated travel presets plus station presets for manual storage.
WMA (Windows Media Audio)
Developed by Microsoft, Windows Media Audio is one of today's most pervasive Internet audio formats. Though not as popular as MP3, proponents of lossy WMA claim that it can outperform MP3 in the area of sound quality, particularly with files encoded at lower bitrates such as 64 or 96 Kbps. This performance advantage makes it handy for applications like portable digital audio players, where total play time is limited by a finite amount of internal memory. The Windows Media Audio format features built-in copy protection abilities, unlike MP3. For more information about all types of file formats, visit our File Formats Glossary.
Some CD receivers feature a circuit that detects periods of no audio signal (a series of zeros in the digital bit stream) and mutes the audio output. You'll hear dead silence until an audio signal is detected again.