The Basics: Receivers

The receiver market has gone through some pretty radical changes following the dramatic shift from VHS to DVD in the home video market. In this revolution is the inclusion of video switching into what used to be the audio receiver. The most significant is the evolution from Dolby Pro Logic surround to 5.1 surround (which has evolved to 6.1 and 7.1 surround sound), which can be produced on DVD from either a Dolby Digital or DTS track. The main difference between the old Pro Logic and the 5.1 or higher formats is simple. Pro Logic is a matrixed signal carried through a stereo signal that requires four speakers--left, center, right and surround. Dolby Digital 5.1 and DTS use six discrete tracks of audio, and require six speakers--left, center, right, left surround, right surround and a subwoofer, allowing for a full-bandwidth signal with extremely precise placement and separation. These six speakers also require six channels of amplification.

DVD-Video uses Dolby Digital 5.1 or DTS to produce the spectacular sound that the format is known for--even satellite TV signals can carry a 5.1 Dolby Digital signal. Dolby Digital is an encoded signal that must be decoded back into six discrete audio tracks. DTS, a competing format isn't quite as popular, is not required to be carried on a DVD-Video. All DVD must contain a Dolby Digital track, although it is not necessary for the Dolby Digital track to be full surround--it can even be a stereo track that is encoded in the Dolby Digital format. Originally, the decoding could be done either in the DVD player or in a Dolby Digital receiver. These days, most DVD players pass the signal, via a digital connection, to an A/V receiver. While these were initially labeled "Dolby Digital receivers," they are now equipped with Dolby Digital, DTS and Dolby Pro Logic II, (a new format that is a significant upgrade from the old Pro Logic format) so they are generically referred to as audio/video (A/V) or home theater receivers.

Due to copyright and piracy concerns, neither DVD-Audio nor SACD will output a digital signal. These players use internal decoders to read the discs and output six channels of analog audio to go to an amplifier. Many of today's amplifiers have six inputs reserved just for this purpose.

While the home theater market has exceeded every manufacturer's wildest dream, the need for two-channel stereo receivers remains strong. Many people still spend plenty of time listening to music, and as long as CD are around, stereo receivers will be a valuable addition, if not a necessity, to the home audio enthusiast. Even a movie-watching fan might consider spending the theater budget on a better-quality stereo receiver that can still deliver two channels of audio rather than a low-price surround receiver. One thing to remember: stereo receivers will only switch audio sources. An A/V receiver is necessary to handle video switching.

How to Shop

While separate Dolby Digital or DTS decoders, preamps, tuners and amplifiers are available, getting them all in one unit saves money and is usually a lot simpler to set up and operate. An A/V receiver is capable of decoding the audio signals, handling switching responsibility for the signal to feed your television set and providing the amplification for all the speakers. Stereo receivers rate their power as "watts per channel," but A/V receivers usually list them as total wattage available for all channels. Most subwoofers are self-powered (with an internal amplifier) which means the receiver does not need to provide it amplification. In addition to decoding Dolby Digital signals, most receivers can decode the older Pro Logic signal and DTS, which is another discrete surround format. These receivers are considered A/V receivers, which means they handle audio switching as well as video.

Since these handle digital audio signals, you'll want to look for a receiver with all the inputs you'll need. A DVD player and a Dolby Digital-equipped satellite receiver could end up fighting for the one optical or coaxial digital audio input. Also, make sure you have enough video inputs -- DVD, satellite, cable, and VCR. If your television is capable of taking a high quality input signal, such as a component video signal or even an HDMI or DVI signal, you'll want to make sure your receiver can switch in these formats.