AV receiver

The history of the receiver begins with the end of the 20s of the 20th century , at which the heyday of broadcasting occurred, when systems from a radio receiver and an amplifier combined in a single package spread around the world. This hybrid was called RECEIVER, which means "receiver". Having existed in this form for more than a decade, recently the receiver has started a new life.

Thanks to the developers of home sound systems, first, the simplest processors of surround effects , operating on the principle of delay and phase shift of the stereo channel signal, were built into it. It was an echo effect in the large hall, when at first the viewer heard the sound coming from the screen, and then after a short but noticeable audible time, the sound reflected from the back and side walls reached him.

Later on, the principle of multi-channel soundtrack recording for the film became widespread. It took more channels of amplification.

Engineers from Dolby Laboratories (USA) suggested using four and then five channels of surround sound first. The principle of recording phonograms on home media, which at that time were mainly video tapes, was also changed. Sound was recorded according to the principle of a mathematical matrix , information for four channels was encoded into two stereo tracks .

For its correct reading and distribution of the received audio data, a decoder was built into the appropriate channels in the receivers. With it, the unit received a slightly longer name - the AV-receiver.

With the development of home cinema and multichannel sound systems for Dolby Digital and DTS films, the number of channels rose first to 6 (later to 8), and audio (and then video) was transmitted via digital interfaces (for example, HDMI ).

Radio

The receiver tuner receives analog signals of two (CB / VHF) or three (DV / CB / VHF) bands. The tuner of the most recent generation of receivers is compatible with RDS . There may also be the possibility of receiving digital radio DAB (can be implemented as a separate or built-in module).

The latest top models of receivers are equipped with the XM-satellite satellite radio module . Some models have an HD Radio tuner, an Ethernet port for receiving streaming Internet radio and connecting to a computer .

Decoders

AV receivers are usually equipped with one or more decoders for sources that have more than two channels of audio data. In most cases, this soundtracks movies. With the advent of DVD , Dolby Digital has become the standard. Most AV receivers have Dolby Digital decoders and at least one S / PDIF digital input for connecting digital output sources.

Later came the DTS format, offering better sound (with less compression). It has also become the standard for multi-channel audio, and DTS decoders are also present on most AV receiver models.

The emergence of higher-density Blu-ray Disc and HD DVD recording media , a high-speed HDMI digital signal transmission interface and lossless compressed multi-channel video formats ( Dolby TrueHD and DTS-HD Master Audio ) have significantly raised the bar for approximating playback sound to the original. .

Effects processor

Most receivers assume the presence of an effects processor that allows you to manipulate various settings and sound effects. In some cases, this is a simple equalizer , sometimes it can be a whole complex to simulate the sound field of a concert hall or stadium (depending on the settings). It is also possible to adjust the delay of the sound through the channels to provide the optimal sound picture (on some models, a measuring microphone is attached for this).

THX is a certificate of special signal processing and compliance of a product with the THX standards. For receivers, this is a processor that reduces the aggressiveness of high-frequency components, making the sound more like the sound in a movie. Amplifier (receiver) with the THX logo has an output power on all channels equal to 100 watts with a rather low level of distortion and can work with speakers of almost any complexity.

Gain

The stereo receiver has two channels of amplification, while the AV receiver has more than two channels. The most common AV-receivers with five channels of amplification. Such receivers are usually called 5.1 receivers . They provide for the connection of loudspeakers of the right, center, left channels, as well as the right and left channels of the environment. 7.1 also implies the presence of additional left and right surround surround channels. The designation “.1” is used to indicate the channel of low-frequency effects, the signal of which is usually fed to the built-in subwoofer amplifier. 5.1 and 7.1 receivers usually do not have an amplifier for this channel.
The signal is output to the line level .

Most receivers use class AB amplifiers. Some manufacturers produce receivers using class D amplifiers; Class D amplifiers are more energy efficient, may be smaller and lighter than equivalent class AB amplifiers.

AV inputs / outputs

AV-receivers have various possibilities for connecting equipment. Standard connectors include:

• analog sound ( RCA connectors and less often XLR ),
• digital sound ( S / PDIF ; TOSLINK or RCA-connector with coaxial cable),
• composite video signal (RCA-connector),
• S-Video analog video,
• Scart analog audio-video signal
• component video (RCA-connectors and less BNC )
• HDMI digital audio video signal.

To connect analog audio sources, RCA connectors are usually used, analog audio outputs are usually used to connect to a VCR or audio deck.

XLR connectors are used less frequently in more expensive models of AV-receivers.

Digital connectivity is used to transfer PCM , Dolby Digital and DTS audio data. These are usually CD and DVD players or satellite receivers. It is also possible to connect the digital output of the computer sound card .

RCA connectors are used for composite connections. Composite video connection is standard for all AV receivers and allows connection of devices such as VHS video recorders, digital television receivers and game consoles. DVD players can also be connected to composite inputs, however, it is preferable to connect them with a wideband connection.

An S-video connection provides higher quality video than a composite signal.

SCART connection contains signals of RGB component video, s-video and composite video with stereo sound. Depending on the type of signal used, the image quality may vary.

The component connection provides the best quality when transferring analog video.

HDMI is used in most modern AV receivers. Through HDMI, it is possible to transmit both sound and video in a digital representation. Different models of AV-receivers support different versions of the standard. Some can only transmit video and do not support multi-channel audio. Some do not support uncompressed PCM multi-channel audio, which is used in Blu-ray Disc and HD DVD players to deliver the best quality sound.

Sources connected via HDMI to the AV receiver can be not only DVD, Blu-ray Disc and HD DVD players, but also a video card of a computer with DVI output. For such a connection, you need a DVI-HDMI adapter. Also, via HDMI it is possible to transfer video from the AV receiver to the LCD display , projector and other modern video display devices that have this connector.

Video Conversion

Some AV receivers can convert video from one format to another. This is called transcoding . A small number of receivers can also deinterlace video signals. For example, a receiver with a set of these functions can convert a composite signal with interlaced 576 lines ( 576i ) to a progressive 720 line ( 720p ) video signal, thus greatly improving its quality when viewed on modern HD Ready or Full HD TVs.

• Dolby Digital (AC-3)
• Thx
• DTS

• The Lord of the Air Waves // Stereo & Video, October 2005

Add illustrations .