AV receiver

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AV receivers or audio-video receivers are one of the many consumer electronics components typically found within a home theatre system. Their primary purpose is to amplify sound from a multitude of possible audio sources as well as route video signals to your TV from various sources. Typically you may program and configure a unit to take inputs from devices such as DVD players VCRs etc. and easily select which source you want to route to your TV and have sound output for.

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[edit] Usage

These AV receivers may be known simply as stereos (although most receivers now-days offer more than two channels or stereophonic sound), receivers, or "Head Units". They are usually at the heart of a typical home theatre setup or may simply be used stand-alone for audio amplification purposes. They offer a broad range of inputs and features that increase with price. Some units such as Denon receivers may cost upwards of many thousands of dollars. They are often drivers for surround sound speaker systems that may be used with anything from MiniDisc players, computers or CD players.

[edit] Features

[edit] Radio reception

Receivers usually have a built in tuner for Amplitude Modulation (AM) and FM radio reception. Satellite radio tuners are also found in many modern receivers, allowing reception with just an external antenna (and a satellite radio subscription, if necessary).

[edit] DSP Effects

Most receivers offer specialized DSP's 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 the audio being played in the places through use of surround sound and echo effects.

[edit] Amplification

There are two types of amplifiers found in receivers "Digital Amplifiers" and "Analog Amplifiers". The analog amplifiers (Class AB Amplifiers) are usually found in higher end units and provide cleaner sound as a result of overcoming quantizing noise by not using manipulation of digitized binary audio streams, which results in less distortion. Although because of the relatively low efficiency of these amplifiers it is more expensive to produce high power units. Class D amplifiers, sometimes misnomered as "digital amplifiers" because of their use of Pulse-width modulation, are more common and a cheap solution for audio amplification. They have more distortion though but better efficiency resulting in more power for less money. Class T amplifiers, which are very similar to Class D amplifiers, correct this by using signal processing. See Amplifiers for more information. Some extremely expensive units may resort to vacuum tube amplification as well.

[edit] AV Inputs/Outputs

As mentioned before there are a wide range of AV inputs available in the back of the receivers making integration of your home theatre components easier. This however often leads to cable spaghetti unless you use optical cables, which use a single thin cable instead of the usual 5 separate channels for surround sound or buy a simple cable management system which are usually just round plastic conduits with a slit for inserting and bunching cables. Typical types of connectors are the RCA connector which is used for both video and audio inputs/outputs, the S/PDIF optical ports and RCA Digital audio connectors which may pass Dolby Pro Logic, Digital Theatre System (DTS) or stereo signals. Also found on the back are the terminal blocks for speaker wires. They typically have impedance values of either 4 Ohms or 8 Ohms. Ensure to match the impedance values for both your speakers and receiver or damage to either portion of the system may occur. Now, modern devices have USB ports for MP3 players or USB flash drives.

[edit] Video conversion and upscaling

Some of the most expensive AV receivers are capable of converting video to some other mode, like composite video to S-video or vice versa. Nowadays there are also some receivers in sub-thousand dollar class, which can convert the video to component or even HDMI-signal, like the Philips DFR9000 or JVC RX-701 (Europe) or RX-702 (America). Upscaling is a bit different thing, it means "inventing" more details to video signal, for example upscaling the 576i (interlaced) video format (720 x 576 pixels) to 720p (progressive, 1280 x 720 pixels). While converting the video from interlaced to progressive, the receivers use some kind of chip to make the conversion, like DCDi system developed by Faroudja.

[edit] External links

  • A block Diagram of a typical Receiver[1]

[edit] See also

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