Sound Advice<\/p>\n
By Don Lindich<\/p>\n
Week 7, 2007<\/p>\n
Q: I’m still hanging on to the old school idea that the best speaker set up for music (not movies) is to take two high quality speakers, place them the correct distance apart in a room with adequate acoustics, and listen. But surround sound is overtaking audio and has obvious advantages for video. Does surround sound, assuming Dolby Pro-Logic II and good equipment, produce a better musical experience than my two-speaker arrangement?<\/p>\n
-Al Barton, Excelsior, MN<\/p>\n
A: This is a beauty is in the eye of the beholder kind of question, so it will vary according to personal tastes. There are two schools of thought, the “purist” approach and the “it’s better” approach. Before we discuss them I will describe the different ways music in surround sound is created.<\/p>\n
“Discrete” surround sound means each channel (or speaker) has its own track which is played through it. Stereo, with two channels and two speakers, is a discrete format. Some music on Super Audio CD (SACD) or DVD-Audio (DVD-A) has more than two channels, for example 5.1 or 6.1. The .1 stands for the subwoofer. It is a separate track but is not full-range, only handling bass frequencies, so it is denoted separately. Each channel is different and can play the full range of audio frequencies.<\/p>\n
“Matrix” surround creates surround sound from stereo sources by either decoding or synthesizing surround information on a two channel source. The original Dolby Pro-Logic was a matrix surround system. Its drawbacks are the limited bandwidth of the surround channels, meaning they only played midrange sounds, with no deep bass or high treble. With Pro-Logic both the left rear and right rear speakers play exactly the same sounds- you can switch the speaker wires and the sound would be exactly the same.<\/p>\n
In the mid-1990s a proprietary format called Six-Axis was introduced by Harman\/Kardon’s high-end Citation company. It created full-range stereo surround from Dolby Pro-Logic sources by selectively mixing information from the front right and left speakers into the surround speakers. Though this may sound kind of a sloppy way to do surround sound, as someone who has owned and used this system I can vouch for its effectiveness and great sound. Dolby Pro-Logic II is a further refinement of the Six-Axis concept. If you are not using Pro-Logic II with TV, you should be- the difference compared to Pro-Logic is dramatic, to say the least.<\/p>\n
Most music recordings are two channel, which means that if you listen in surround you will be hearing an “artificially created” performance as you will not be hearing the material in any way the creator intended- the surround process is altering the signal and sending it to the rear speakers, where it was never really intended to go. This brings us to the purist approach- trueness to the source. If it is stereo, you listen with two speakers. If it is a multi-channel surround SACD or DVD-A, you listen in surround. \u00a0 Anything else is less than high fidelity.<\/p>\n
The “it sounds better” camp states the spaciousness and seemingly greater realism of surround. Jim Fosgate is the audio engineer responsible for most of the advances in surround sound systems, having developed both Six-Axis and Dolby Pro-Logic II, and he is very much in this camp, but backs it up with scientificevidence. In manuals for Citation gear he designed, studies were quoted where more than two speakers were deemed necessary for effective stereo imaging- which could be inferred that it is more accurate than simple two-channel.<\/p>\n
So what it comes down to is there is no solid answer and it is all personal preference. Try them both and go with what you like best. You will probably find your preference varies with each individual recording- some will sound better in surround, others in stereo.<\/p>\n