“5.1” and “7.1” are popular marketing terms today for modern home theater equipment. What does it all mean? This article will explain the different channel configurations for audio playback and, hopefully, help you make a decision as to which is best for your listening experience.
In the early days of audio, you would wind up your Victrola and listen to an acoustially-recorded shellac disc through a horn speaker. Or, the family would gather around the radio and listen to the latest Big Band hits coming out of a single speaker. This is good old monaural sound–one channel of sound.
In the 50s, engineers felt that a sense of position would help convey more realism in recorded music. And indeed it did: RCA was one of the first to introduce stereophonic sound, which emanated from two speakers, thus launching their still-sought-after Living Stereo recordings. If properly reproduced, you could hear the violin section on the left, or even that minor squeak coming from the bassoonist’s chair somewhere near the center of the orchestra.
The 70s brought us quadraphonic sound. Unfortunately, quad suffered from having three incompatible playback formats on LP, and it never really took off. Quad reel tapes and 8-tracks never really caught on either, but remain popular among quad collectors, including an avid community of enthusiasts who convert these old tapes and LPs to multichannel DTS or DVD-Audio to play back over their modern surround systems. (Be sure to pay a visit to the Quadraphonic Quad website and forum if you’re interested in quad and any other surround format.)
The original Star Wars film introduced moviegoers to surround sound: during the opening scene, the battle cruiser roars overhead from behind, and in properly equipped theaters, you heard it coming from behind!
After several years, surround playback in the home became more feasible, and today we have products that provide as many as seven channels!
Today you see terminology that relates to the number of channels a system is capable of reproducing, and it is given as a number. For instance, the system I have in my den, for DVD playback, consists of a 5.1 channel receiver driving five speakers and a subwoofer. The “5” refers to the number of “directional” channels, where the “.1″ refers to the LFE (low frequency effects) or subwoofer channel, which only reproduces really low bass sounds. Using this terminology:
1.0 is monaural sound;
2.0 is stereo sound, with speakers left and right;
4.0 would be the old quadraphonic system, with a pair of speakers both in frond and behind you;
5.1 is a set of speakers: left front, center, right front, right rear, left rear, plus an LFE channel.
There are now additional channels: you often see systems advertised as having 7.1 channels. Do you need all of those 7.1 channels? Not today. Consider this: all movies mastered to DVD are only encoded with 5.1 channels of sound, so anything using 7.1 channels would have to be “calculated” to fill in those additional two speakers. Don’t let it stop you from buying equipment that supports it, as you have the option of not using the extra channels.
For audio playback, though, you have a choice. Most listeners today use a stereo configuration, with left and right channels. Some dedicated listeners, though, can enjoy surround-sound music, thanks to products like SACD (Super Audio CD), DVD-Audio (DVD-A), DTS CDs (which only play back in DTS-capable DVD players), DualDiscs (which have a CD side and a DVD side), and DVDs that contain a Dolby Digital surround presentation, just like video DVDs have. While the music discs can sometimes be hard to locate, there are still many out there, including classic albums that have been remixed for surround sound.
Whether you like surround music or not is a personal preference. If you like it enough to make the investment, and have room for the additional speakers, surround sound can give you an additional listening experience that stereo can’t provide.