The A/V receiver is the centerpiece of any home-theater system. Its main function is to route sound and picture from different sources--DVD, cable TV, CD, turntable, etc.--to your speakers and television. The receiver doubles as an AM/FM tuner and typically controls everything from surround-sound decoding (such as Dolby Pro Logic, Dolby Digital, Dolby Digital TRUEHD Digital Theater Sound-High Definition (DTS-HD) and Digital Theater Sound (DTS)) to tone controls (bass and treble), as well as master volume.  Modern A/V receivers have High Definition Multimedia Interface (HDMI) inputs and outputs.  It allows for seamless video switching through the receivers to the television.  Since it's useful for stereo audio and standard TV, an A/V receiver is usually the best place to start building a home-theater system, even if you don't yet own a DVD or Blu-ray player.

Surround Sound: Dolby Pro Logic, Dolby Digital Dolby TRUEHD, and DTS-HD Master Audio
At the heart of a modern A/V receiver is the surround-sound processor. The most basic surround processors use a Dolby Pro Logic decoder. Pro Logic is a "matrix" system that takes an encoded two-channel stereo signal and converts it to four channels: left, center, right, and monophonic, frequency-limited surround. Many television shows and most commercials are encoded in Dolby Pro Logic.

The introduction of DVD has seen state-of-the-art, movie-theater-quality, 5.1-channel Dolby Digital as the new surround-sound standard. With five channels of discrete, full-frequency sound plus a low frequency “effects” channel (the ".1"), Dolby Digital--formerly called AC-3--has revolutionized home-theater sound.

High definition Blu-ray players surround sound codecs have increased the overall sound quality over standard DVD players.  Dolby Digital TRUEHD and DTS-HD Master Audio provides stunning, uncompressed, audio playback of a movie soundtracks.  Standard DVD players have the surround soundtracks compressed onto the disc mush like MP3 Music playback on your portable music device.  Connecting your Blu-ray player to your receiver via HDMI, allow surround sound formats to transmit directly to your receiver from a single cable.  The receiver processes the movie soundtrack using Dolby Digital TRUEHD and DTS-HD Master Audio processor formats.

In addition to Dolby Digital, many A/V receivers now include DTS decoding, which is another 5.1-channel system. DTS uses a lower digital-compression rate than Dolby Digital (1:4 for DTS vs. 1:12 for Dolby Digital), and it tends to sound better. DTS requires three times more disc space, limiting the length of movie soundtracks and special features such as a film's additional language tracks. There are only a few DTS-encoded movies on DVD right now, but a large and growing collection of surround-sound audio music already exists in this format, including many popular rock and classical recordings spanning the last 30 years. If you're interested in surround-sound music, make sure your receiver includes DTS capabilities.

Digital Signal Processing
Many A/V receivers include powerful digital signal processing (DSP) programs that can synthesize surround-sound emulations of churches, stadiums, nightclubs, and other venues. Depending on your program material, these copies amount to little more than novelty effects, but they can enhance your listening experience.

While Dolby Digital, DTS, and DSP surround processing all occur in the digital domain, the final sound output must come from your analog speakers. Receivers use a multi-channel digital-to-analog converter (DAC) to create the final analog signal passed on to your speakers. These DACs vary greatly in sound quality.

Inputs
Most new A/V receivers include HDMI inputs to accept both audio and video from your sources. Sources may include satellite receivers, cable boxes, Blu-ray players, and video game systems. The audio signal from a single HDMI cable is processed internally using the Dolby Digital and DTS processors. The majority of the receivers will auto detect the soundtrack and playback the appropriate version. The receiver sends the video signal to the TV or projector via the HDMI output jack.

Receivers still have input sources such as analog audio and component video (legacy input sources). Analog audio sources can be tape decks, turntables, and portable music players. Component video sources consist of standard DVD players and video game systems.

If you frequently use your camcorder with your home theater setup, be sure your receiver includes a set of convenient front-panel A/V jacks. If you max out on video sources, outboard video source selectors can also come in handy.

Outputs
Receivers have speaker level and line level outputs. Most importantly, a receiver should directly connect to the television or projector by an HDMI cable. The video that comes into the receiver from the inputs is output via the HDMI cable. Standard DVD player’s images are scaled through the HDMI output to display on your television at a higher resolution when connected by component video connections (red, blue, and green cables).

Speaker outputs on modern receivers consist of 5.1 or 7.1 channel outputs. Basic surround sound set-up is five speakers and a sub-woofer, usually three front and two back speakers. The 7.1 channel set up consists of two additional side speakers.

Amplifier Power
For the best performance, when it comes to power, we recommend a minimum of 100 watts per channel, 20-20,000 Hz, all channels driven. Power is the most skewed specification in home theater. For example, a manufacturer might give their two-channel receiver a rating of 100 watts at 20-20,000 Hz. A five-channel playback rating might seem similar to a two-channel, but it actually means something very different: 100 watts at 1000 Hz, for example. It’s given for one frequency, not the entire range, the second spec probably means there is a significant power drop-off at the frequency extremes when all five channels are in use. The bottom line is when looking at power ratings, try to get a rating that covers the full audio spectrum, not just one frequency.

Price Range
Receivers have a wide price range, they run somewhere between $199 to $2499.

Revised 06/02/10