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Surround Sound for your home theater is quite a desirable thing, but it comes at a considerable expense. Cheap surround sound systems with built-in DVD players are affordable, but they are usually a very bad investment because of the poor quality and cheap materials involved in their construction. Good quality audio systems with surround sound capability don't come cheap, and neither do all those little fancy surround sound speakers, should you decide on a system where they are sold separately. It can also be annoying to know you will have to replace your old faithful stereo system, even though it might be in perfect condition.
Wouldn't it be nice if you could just use your existing stereo
receiver (and speakers) as your surround sound system?
Well, you can! (With certain limitations)
The difference between mono sound, surround sound and stereo sound is simple. Suppose you're watching a live concert on TV:
Mono sound produces one distinct "channel" of sound. Ideally, the sound source (speaker position) should be at front center. So as you face the screen to watch, the sound will come from the image on the screen.
Stereo sound produces two distinct "channels" of sound - left and right. So a musician on the left side of the stage will sound like he/she is on the left side of the stage, and one on the right will sound like they are on the right, but one in the center would be blended into the center from both sides (still a nice improvement over mono, but not perfect)
Surround sound produces several "channels" of sound - usually left, right, center (in front of the listener in their respective positions), and rear (which is usually handled by two speakers on the left and right behind the listener). So, as you are watching your concert, sounds would come from the left and right and center of the stage as they should, and you could hear the echo from the back of the concert hall behind you. (pretty close to realism!)
I'll assume you already feed your video signal sound, from a DVD player, stereo TV, dish receiver, or anything with left and right "audio out" jacks into your stereo system, and your left and right speakers are on either side of your TV.
The type of surround sound you can get from a stereo amplifier with this method sounds very similar to the "Phantom Surround" setting on many surround sound systems. Phantom surround does not use a center channel speaker, only front left and right, (which you already have) and two rear speakers (which you don't have.....yet)
You need a pair of small speakers for the rear sound. They don't have to be very high powered because the rear channel does not contain a lot of volume. Place these speakers behind the listening area, on either side.
ConnectionsDo not change the hook up of your existing left and right speakers. All you need to do is add on another pair for the rear. If your amplifier is like most stereo units, then it's probably capable of driving either 2 or 4 speakers. Most people only have 2, leaving the second speaker connections unused. In this case it's easy, just use the "B" speaker connections for the rear surround speakers. If your amplifier doesn't have a spare set of speaker connectors, then you can likely "piggyback" the surround speaker connections with the main speakers if your amplifier is only driving 2 speakers. Trying to run 6 speakers with one amplifier will likely result in amplifier damage for which I will not assume any responsibility.
You will notice that the hook up for the rear surround speakers is rather unusual. For one, there is no common (-) connection, and they appear to be connected out of phase with each other. You may wish to separate some twin lead speaker wire to do the hook up, or run twin lead from the amplifier to both rear speakers, and do all the weird connecting of the rear speakers behind the amplifier. If you do twist leads together behind the amplifier, make sure you tape up any bare wires. This is important.
With this setup, powered by a stereo amplifier, proper functionality of the rear surround channel relies heavily on a very precise adjustment of the balance control. Usually, just being "in the center" is not good enough. To adjust the balance control, play a mono signal through the system, by pushing the receiver's MONO button, or turning the stereo decoder off when tuned to an FM station. AM radio is also mono. Set the volume to a normal level. If you have a speaker switch, and you can turn off the main speakers, leaving only the rear surround speakers on, do it. You will notice that the balance control greatly affects the volume of the rear speakers. Ideally, you want the spot with the least sound (no mono signal), which is close to the center position. When you find it, switch the main speakers back on and try a stereo signal. The effect should be quite dramatic with music, but there won't be much there on dialog portions of a movie, and there shouldn't be because it's mono. Mono dialog only plays through the front center speaker on real surround systems, and it will with this setup as well. Cool, huh? Special effects can sound pretty slick, especially when you consider that this "surround sound" is coming from a plain stereo amplifier with no surround decoder! I have seen it fool owners of real surround sound systems, who couldn't believe an old Marantz 2245 was capable of creating such effects!