Surround Sound - Part III

Amplification

If you buy separate processor, then you will need power amplifiers to go with it. Many companies manufacture power amplifiers that have 3-7 separate channels built into one package. They offer 100 watts - 400 watts per channel or more, and cost upwards from about $1,000.  If you get a receiver with pre-out jacks (these deliver the preamplified sound to a jack so you can connect a separate power amplifier), you can upgrade at any time in the future with these same, more powerful multi-channel amplifiers.

There is no substitute for raw power in home theater sound. Whether receiver or separates, as a general rule, we feel that at least 100 watts are needed for each channel. This is in watts continuous or RMS, not peak power watts, and at 8 ohms speaker impedance. Many integrated packages (surround sound receivers) offer this much power, and we suggest getting as much power as you can afford. Even though you will only be using about 15 - 50 watts per channel at any one time, having the capability of high power output will result in these 15 - 50 watts being on the "linear" portion of the distortion curve, which means it will sound much better than if the amplifier had a capability of only 50 watts per channel, and you were running the amplifier at full output all the time. Also, you will be surprised at how much impact a loud special effect can have when 100 - 200 watts are available to drive it.

Connections - Stereo
Stereo Analog Audio Jacks

Connections Stereo/Video
Stereo Analog Audio Jacks plus Composite and S-Video

Connection Digital
Coax (top) and Optical (bottom) Digital Audio Jacks

Connections - Preouts
7.1 Pre-Out Jacks

Connections - Speakers
Speaker Binding Posts

DVI jack
DVI Jack

Connection - HDMI
HDMI Next-Generation Digital Audio AND Digital Video Connection

Connectors and Other Features

Whether you purchase an integrated A/V Receiver or separate surround sound processor and power amplifiers, you will need a large number of connectors on the back. There should be analog stereo inputs for things like a CD player, DVD player, satellite or cable TV receiver, AM/FM tuner (if a tuner is not built in), phono (important if you still play records), VCRs, audio cassette decks, and so on. There should be digital audio inputs of both the coax and optical variety for DVD, CD, and Satellite tuner.  The unit might also have one or more DVI jacks for switching HDTV video signals, or HDMI digital inputs for switching HDTV audio and video signals (HDMI will also pass digital DVD-A music signals).

The inputs may not all be labeled exactly the same way on every receiver, so you should ask the salesperson about the number of inputs, and ability to connect the above mentioned sources. Capability of dubbing from one audio cassette deck to another, and one VCR to another should be present (you won't be able to copy DVD movies to your VCR since copy protection in the DVD prevents this).

If you are looking at a separate processor, it will have 5, 6, 7, or even 8 line-level audio outputs for connecting to power amplifiers: front left, center, front right, left/right surround (plus left/right rear or center surround for the various Surround EX stuff), and at least one subwoofer out. As we've mentioned, even with A/V Receivers it is nice to have a complete set of pre-out jacks should you decide to upgrade to higher quality power amplifiers later. It is a feature to look for.

If you want to have Dolby Digital with older laserdiscs, then the receiver or processor should have an AC-3 RF input jack. This takes the RF signal from the laserdisc player, containing the DD signal, and demodulates it in preparation for decoding.  DVD players may have a Toslink optical digital output jack, and/or a coaxial digital output jack. Receivers these days tend to have both types of digital input jacks, but you should make sure that the digital output on your DVD player matches the input on your receiver.

The receiver will also have speaker connectors. The best are binding posts that allow you to connect bare wire, spade lugs (they look like small two pronged forks), or banana plugs. Less expensive models will have simple spring clips.

Surround Sound Alternatives

The surround sound processors and receivers these days are very flexible.  You can for example use just two speakers if space or budget is limited.  The surround sound decoder will "downmix" any surround soundtrack into the two channels so you wont miss any of the sound, you'll just be missing the surround effect of it. 

You can go without a center channel, having it sent to the front left and right speakers, but still keep the surround channels.  Some processors even offer "virtual surround" where if you are perfectly seated between the left and right speakers, it fools your brain into thinking some sounds are coming from behind you.

While all this can "get you by", ultimately there is no substitute for full surround sound!  If for example you choose not to use a center speaker and you are seated even slightly off center, dialogue during the movie will appear to come from the speaker closest to you, and not from the video image as it should.