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Home Theater Receivers Choosing the receiver for your home theater is one of the most important decisions you'll have to make. To keep up with all of the newest outputs of the newest audio and video formats, you'd probably have to buy a receiver every year. This section will help you to decide which features you really need and which you can do without. Power Output: There are many different amplifier configurations. To reproduce the full 5.1 channels of surround sound, you will need 6 channels of amplification. When shopping for a new receiver, you should realize that not all receivers have the same power (or sometimes no power) for all 6 channels. Many times the 2 rear surround channels have half (or less) the power of the front 3 channels. Some receivers even have reduced power for the center channel which, if you are buying the receiver specifically for home theater, is definitely undesirable. You should also look at the specifications to make sure that the power ratings specify that the power output was measured with all channels driven at the same time. If they measure the power output with only the left and right channels driven, the output power ratings will be higher than the actual power output when all of the channels are driven. Now, I'm not saying that the receivers that specify the power output with only 2 channels driven are not good quality receivers. I just think that you should be aware that different manufacturers measure output power in different ways and when comparing different receivers, you need to note precisely how the the power output was measured. The speaker outputs (from the receiver's internal amplifiers) will all be clearly marked and will simply be connected to the appropriate speakers. Preamp Outputs: Some receiver manufacturers which supply limited or no power amplification for the center or rear surround channels. These receivers may supply a preamp output or a preamp/main amp input loop. The preamp only jack would be used to drive an external amplifier. The preamp out/main amp input loop is a jumper that connects the preamplifier for one of the 6 channels to the built in amplifier for that particular channel. If the built in power amplifier doesn't have sufficient power, the jumper can be removed and the preamp output could be connected to an external amplifier. The output level of all of these preamp outputs are controlled by the volume control. A higher volume setting will produce more preamp level output. A minimum volume setting will produce no output. Tape out/VCR Output: There are some other output connectors that are used for recording to a VCR or cassette tape recorder. These connectors are usually marked as 'tape out' or 'record out'. THese outputs have fixed output levels and are not suitable to drive a power amplifier. The output signal is the signal from the selected source (FM, AM, CD, DVD...) Tape In/VCR Input: This input is used for playback of the audio signal of your tape players and VCRs. When you select one of the tape or VCR sources, the signal that is driven into the corresponding tape/VCR input is played through the system. Video Inputs: Most receivers designated as 'home theater' receivers will have some sort of video switching. The following few sections will cover the basics of each of the most common inputs. Most of these inputs offer switching of sources. There are generally no controls to modify the video signal in any way. Composite Video: This is by_far the most common input on home theater receivers. It uses a RCA type connector and a standard RCA cable to transfer the signal. All of the video information is delivered on a single center conductor. The outer conductor is used as a reference and is generally connected to ground. If you have a 3 conductor RCA interconnect cable, the yellow connector is used for the video signal. S-Video: This type of interconnect uses a 4 pin DIN connector. An S-Video cable delivers 2 signals designated as 'Y' and 'C'. Y is the luminance signal and contains all of the information that would be contained in a black and white signal. C is the chroma signal and contains the color information. The separation of signals provides a better picture than composite video. Component Video: This type of interconnect consists of 3 individually shielded cables with RCA type connectors. They are marked 'Y' (as above), 'Pr' (red information) and 'Pb' (blue information). The cables are color coded yellow, red and blue (respectively). This type of interconnect divides the signal even more than the S-Video signal and is supposed to deliver even better picture quality than S-Video. RGB Video: This type of interconnect also uses 3 individually shielded cables with RCA connectors. This signal has information for the 3 colors that are used to reproduce the video picture (red, green and blue). This is generally available for use on video monitors (especially those that are designed to use as computer monitors). Decoders: Some home theater receivers (HTRs) have built in surround decoders. Most HTRs with decoders can decode Dolby Pro-Logic signals from a stereo signal. Virtually all of the newest HTRs have built in Dolby Digital decoders which can accept a digital signal from a DVD player (or other digital source) and decode it to the necessary 5.1 channels. An ever increasing number of HTRs can also decode the DTS surround signal. At this time, DTS encoded discs are not as common/available as Dolby Digital encoded dscs. Some HTRs are 5.1 channel ready. This means that the receiver can accept the 6 analog signals needed to reproduce the surround sound effects.