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An audio/video receiver (AVR) is a
consumer electronics Consumer electronics or home electronics are electronic (analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usually r ...
component used in a home theater. Its purpose is to receive audio and video signals from a number of sources, and to process them and provide
power amplifier An audio power amplifier (or power amp) is an electronic amplifier that amplifies low-power electronic audio signals, such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspea ...
s to drive loudspeakers and route the video to displays such as a
television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
,
monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West ...
or
video projector A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. Video projectors use a very bright ultra-high-performance lamp (a special mercury arc lamp), X ...
. Inputs may come from a
satellite receiver A satellite dish is a dish-shaped type of parabolic antenna designed to receive or transmit information by radio waves to or from a communication satellite. The term most commonly means a dish which receives direct-broadcast satellite television ...
,
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
,
DVD players A DVD player is a device that plays DVDs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. Some DVD players will also play audio CDs. DVD players are connected to a television to wa ...
, Blu-ray Disc players,
VCRs A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette, and can play back the recordin ...
or
video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can be played with a game controller. These may be home video game console, home consoles, which are generally placed i ...
s, among others. The AVR source selection and settings such as volume, are typically set by a
remote controller In electronics, a remote control (also known as a remote or clicker) is an electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operate devices such as ...
.


Usage

The term "receiver" basically refers to an
amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the v ...
, typically at least a two-channel stereo model, that has a built-in radio tuner. With A/V receivers, the basic functionality is to receive an audio signal, amplify the audio signal to drive multiple speakers, and allow pass-through of the corresponding video signal to a display device such as a projector or a television. The receiver performs tasks that would otherwise require numerous separate pieces of equipment, such as preamplifiers, equalizers, multiple power amplifiers, and so on. As home entertainment options expanded in the 1980s and 1990s, so did the role of the receiver. The ability to handle a variety of digital audio signals was added. More amplifiers were added for surround-sound playback. Video switching was added to simplify changing from one device to another, though this role diminished again once TVs began supporting multiples of the same type of input connector. The term audio/video receiver (AVR) or Home Theater Receiver is used to distinguish the multi-channel audio/video receiver (home theater receiver) from the simpler stereo receiver, though the primary function of both is amplification. AV receivers may also be known as ''digital audio-video receivers'' or ''digital media renderers''. The AV receiver is classified as an audio frequency electronic amplifier. But with the addition of several features in the 2000s, AV receivers in the 2010s generally have significant additional functionality.


Features


Channels

Stereo receivers have two channels of amplification (thus two separate amplifiers), while AV receivers may have more than two. The standard for AV receivers is five channels of amplification (thus five separate amplifiers), usually referred to as 5.1 receivers. This provides for a left, right, center, left
surround sound Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround the listener ( surround channels). Its first application was in movie theaters. Prior to sur ...
and right surround sound speaker to be powered by the receiver. In the 2010s, 7.1 receivers became more common and provide for two additional surround channels, left rear surround and right rear surround. The ".1" refers to the LFE (low-frequency effects/bass) channel, the signal of which is usually sent to an amplified
subwoofer A subwoofer (or sub) is a loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be (optimally) generated by a woofer. The typical frequency range for a subwoofer i ...
unit. 5.1 and 7.1 receivers do not usually provide amplification for this channel. Instead, they provide a
line level Line level is the specified strength of an audio signal used to transmit analog audio between components such as CD and DVD players, television sets, audio amplifiers, and mixing consoles. Line level sits between other levels of audio signal ...
output. The user then either buys a separate monophonic power amp for their subwoofer or obtains a powered subwoofer cabinet, which contains an integrated power amplifier.


Amplifier power

Audio amplifier power, normally specified in watts, is not always as significant as it may seem from the specification. Due to the logarithmic nature of human hearing, audio power or sound pressure level (SPL), must be increased by ten times to sound twice as loud. This is why SPL is measured on a logarithmic scale in decibels (dBs). An increase of 10dBs results in a perceived doubling of loudness. Another complication with human hearing is that as the SPL decreases the perceived volume of the low and high frequencies decreases faster than the central frequencies around 2 kHz. There are different standards for rating amplifier power depending on country, manufacturer, and model. Other factors also come into play: distortion, headroom, speaker efficiency. As well, some lower-price point manufacturers advertise the peak power of an amplifier, rather than its root mean square (RMS) power. Thus, it is possible for an amplifier with a specified lower power to sound louder than an amplifier with a specified higher power. Because of these factors, it is not easy to compare the perceived loudness of amplifiers solely from their specified power in watts.


Decoders

AV receivers usually provide one or more decoders for sources with more than two channels of audio information. This is most common with movie soundtracks, which use one of a variety of different types of encoding formats. The first common soundtrack format was Dolby Pro Logic, a surround sound processing technology. This format contains a center channel and a surround channel mixed into the left and right channels using a process called matrixing, providing a total of four channels. Receivers with Dolby Pro Logic decoders can separate out the center and surround channels from the left and right channels. With the introduction of the
DVD The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
, the
Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is lossy ...
format became a standard. Dolby Digital ready receivers included inputs and amplifiers for the additional channels. Most current AV receivers provide a
Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is lossy ...
decoder and at least one digital
S/PDIF S/PDIF (Sony/Philips Digital Interface) is a type of digital audio interface used in consumer audio equipment to output audio over relatively short distances. The signal is transmitted over either a coaxial cable (using RCA or BNC connectors) ...
input which can be connected to a source which provides a
Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is lossy ...
output. A somewhat less common surround sound decoder called DTS is standard on current AV receivers. When Dolby Labs and DTS introduced technologies to add a rear center surround channel, these technologies found their way into AV Receivers. Receivers with six amplifiers (known as 6.1 receivers) will typically have both Dolby and DTS's technologies. These are
Dolby Digital EX Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression (data), audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995 in film, ...
and
DTS ES DTS, Inc. (originally Digital Theater Systems) is an American company that makes multichannel audio technologies for film and video. Based in Calabasas, California, the company introduced its DTS technology in 1993 as a competitor to Dolby Labor ...
. Dolby introduced
Dolby Pro Logic II Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround. Dolby Stereo (also known as ''Dolby MP'' or ''Dolby SVA'') was developed by Dolby in 1976 f ...
to allow stereo sources to play back as if they were encoded in surround sound. DTS introduced a similar technology, Neo:6. These decoders have become common on most current receivers. As the number of playback channels was increased on receivers, other decoders have been added to some receivers. For example, Dolby Labs created
Dolby Pro Logic IIx Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround. Dolby Stereo (also known as ''Dolby MP'' or ''Dolby SVA'') was developed by Dolby in 1976 f ...
to take advantage of receivers with more than five channels of playback. With the introduction of high definition players (e.g.
Blu-ray Disc The Blu-ray Disc (BD), often known simply as Blu-ray, is a Digital media, digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and c ...
and
HD DVD HD DVD (short for High Definition Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to th ...
), yet more decoders have been added to some receivers. Lossless
Dolby TrueHD Dolby TrueHD is a lossless, multi-channel audio codec developed by Dolby Laboratories for home video, used principally in Blu-ray Disc and compatible hardware. Dolby TrueHD, along with Dolby Digital Plus (E-AC-3) and Dolby AC-4, is one of the i ...
and
DTS-HD Master Audio DTS-HD Master Audio (DTS-HD MA; known as DTS++ before 2004) is a multi-channel, lossless audio codec developed by DTS as an extension of the lossy DTS Coherent Acoustics codec (DTS CA; usually itself referred to as just DTS). Rather than being ...
decoders are available on many receivers. While Dolby Digital has been the standard for television and video games, Dolby Digital Plus has been adopted for online streaming services such as Netflix, and adds a much higher bit rate and can support more channels.
Dolby Atmos Dolby Atmos is a surround sound technology developed by Dolby Laboratories. It expands on existing surround sound systems by adding height channels, allowing sounds to be interpreted as three-dimensional objects with neither horizontal, nor verti ...
and DTS:X adds in ceiling height channels.


DSP effects

Most receivers offer specialized
digital signal processor A digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on MOS integrated circuit chips. They are widely used in audio si ...
s (DSP) made for handling various presets and audio effects. Some may offer simple equalizers and balance adjustments to complex DSP audio field simulations such as "Hall", "Arena", "Opera", etc. that simulate or attempt to replicate the reverb as if the audio were being played in the places through use of surround sound and echo effects.


AV inputs/outputs

There are a variety of possible connections on an AV receiver. Standard connectors include: * Analog audio (
RCA connector The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name ''RCA'' derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connectors male plug and ...
, or occasionally
XLR connector The XLR connector is a type of electrical connector primarily used in professional audio, video, and stage lighting equipment. XLR connectors are cylindical in design, and have three to seven connector pins, and are often employed for analog b ...
) * Digital audio (
S/PDIF S/PDIF (Sony/Philips Digital Interface) is a type of digital audio interface used in consumer audio equipment to output audio over relatively short distances. The signal is transmitted over either a coaxial cable (using RCA or BNC connectors) ...
;
TOSLINK TOSLINK (from ''Toshiba Link'') is a standardized optical fiber connector system. Also known generically as optical audio, its most common use is in consumer audio equipment (via a "digital optical" socket), where it carries a digital audio st ...
or RCA terminated
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...
) *
Composite video Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
(RCA connector) *
S-Video S-Video (also known as separate video, Y/C, and erroneously Super-Video ) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate channe ...
*
SCART SCART (also known as or , especially in France, 21-pin EuroSCART in marketing by Sharp in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard and associated 21- ...
video (primarily used in Europe and very uncommon in many other parts of the world) *
Component video Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Compon ...
*
HDMI High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, ...
*
USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
(usually involves special computer circuitry to read video formats from a file system) Analog audio connections usually use RCA plugs in stereo pairs. Inputs and outputs are both common. Outputs are provided mainly for cassette tape decks. Analog audio connections using XLR (Balanced) connectors are uncommon, and are usually found on more expensive receivers. Some receivers are also equipped with phono inputs, for connecting a turntable with a magnetic cartridge, although many receivers are lacking this input. In the last years, since vinyl players are gaining popularity, there are some manufacturers of A/V receivers which are offering a phono input on some models. Some receivers also have a selector for either MM/MC cartridge type, or even an impedance selector for cartridge, or some May have more than one Phono input. This feature is mainly offered to allow people owning a turntable to connect it and listen to their vinyl collection. Most receivers will only play in stereo, either front or main speakers, but some receivers may play on all speakers depending on the manufacturer and model. Digital connections allow for the transmission of PCM,
Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is lossy ...
or DTS audio. Common devices include CD players, DVD players, or satellite receivers. Composite video connections use a single RCA plug on each end. Composite video is standard on all AV receivers allowing for the switching of video devices such as VHS players, cable boxes, and game consoles. DVD players may be connected via composite video connectors although a higher bandwidth connection is recommended. S-Video connections offer better quality than composite video. It uses a DIN jack. SCART connections generally offer the best quality video at standard-definition, due to the use of pure RGB signalling (although composite and S-Video may alternatively be offered over a SCART connector). SCART provides video and audio in one connection. Component video has become the best connection for analog video as higher definitions such as
720p 720p (1280×720 px; also called HD ready, standard HD or just HD) is a progressive HDTV signal format with 720 horizontal lines/1280 columns and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcast ...
have become common. The
YPbPr YPbPr or Y'PbPr, also written as , is a color space used in video electronics, in particular in reference to component video cables. YPBPR is gamma corrected YCBCR color space (it is not analog YUV that was used for analog TV, though component ...
signalling provides a good compromise between resolution and colour definition.
HDMI High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, ...
has become the de facto standard for passing video and audio on AV receivers. Features supported through HDMI may include pass-through of 4K, 8K, and HDR video, audio return channel (ARC), enhanced audio return channel (eARC), variable refresh rate (VRR), and pass-through of object-based audio formats such as
Dolby Atmos Dolby Atmos is a surround sound technology developed by Dolby Laboratories. It expands on existing surround sound systems by adding height channels, allowing sounds to be interpreted as three-dimensional objects with neither horizontal, nor verti ...
and DTS:X.


Video conversion and upscaling

Some AV Receivers can convert from one video format to another. This is commonly called upconversion or
transcoding Transcoding is the direct digital-to-digital conversion of one encoding to another, such as for video data files, audio files (e.g., MP3, WAV), or character encoding (e.g., UTF-8, ISO/IEC 8859). This is usually done in cases where a target devic ...
. A smaller number of receivers provide for de-interlacing of video signals. For example, a receiver with upconversion, deinterlacing and upscaling can take an interlaced composite signal at
480i 480i is the video mode used for standard-definition digital television in the Caribbean, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay, and Uruguay). The ''480 ...
(480 lines per frame sent as a field of 240 even numbered lines 0,2,4,8...478 followed by a field of 240 odd numbered lines 1,3,5,...479) and convert it to component video while also deinterlacing and upscaling it to a higher resolution such as
720p 720p (1280×720 px; also called HD ready, standard HD or just HD) is a progressive HDTV signal format with 720 horizontal lines/1280 columns and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcast ...
(720 lines per frame with all lines in normal sequence 0,1,2...719).


Radio on AVRs

AV receivers though primarily used for amplification may or may not have an inbuilt AM/FM radio tuner among other features such as LAN connectivity for various Internet applications and some with multi-room audio solutions. Even though some AVRs may have an AM/FM tuner it is not a primary or mandatory function as an AVR still remains an amplifier. Some models have
HD Radio HD Radio (HDR) is a trademark for an in-band on-channel (IBOC) digital radio broadcast technology. It generally simulcasts an existing analog radio station in digital format with less noise and with additional text information. HD Radio is used ...
tuner. Also some models May have a digital Radio, DAB/DAB+, for some markets. Some models have
Internet radio Online radio (also web radio, net radio, streaming radio, e-radio, IP radio, Internet radio) is a digital audio service transmitted via the Internet. Broadcasting on the Internet is usually referred to as webcasting since it is not transmitted ...
and PC streaming access capabilities with an Ethernet port.


See also

*
Amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the v ...
*
THX THX Ltd. is an American company that develops the eponymous high fidelity audio/visual reproduction standards for movie theaters, screening rooms, home theaters, computer speakers, gaming consoles, car audio systems, and video games. Founded ...
* Digital media player *
Home cinema Home cinema, also called home theaters or theater rooms, are home entertainment audio-visual systems that seek to reproduce a movie theater experience and mood using consumer electronics-grade video and audio equipment that is set up in a room ...
*
Home theater PC A home theater PC (HTPC) or media center computer is a technological convergence, convergent device that combines some or all the capabilities of a personal computer with a software application that focuses on video, photo, audio playback, and ...
(HTPC)


References

{{Reflist


External links


Block Diagram of a typical Receiver


Consumer electronics Home video Set-top box