Surrounded By Space
A string quartet or Dixieland combo might fit, physically, but that doesn't mean you'd want to listen to them in your room either. Live instruments heard from that close in a small, confined space are positively deafening. No, the concept of instruments-in-your-living-room is strictly cart-before-horse, and most audiophiles have come to see that. Today, the goal of high fidelity is quite the opposite: to transport the listener into the room where the recording was made. The means exist now for doing that, but no one is taking advantage of them.
Before stereo, audiophiles who thought at all about what they were trying to do thought about high-fidelity reproduction as a window on the original sounds; sort of a hole in the living-room wall, through which the listener eavesdropped on the concert hall. But with only a mono source, it was a very small window. Various expedients were tried to widen the window---using two different, widely spaced speakers, bouncing the sound off a wall surface---but the result was only a broadening of the hole; there was no reproduction of directionality or spaciousness.
Stereo widened the hole in the wall, opening up the field of view enough that a listener could tell whether instruments were to the right, left, or center of the performing stage, and even encompassing some of the hall sound to the sides of the orchestra. Good stereo reproduction can give the impression that the whole listening-room wall behind the loudspeaker has become a picture-window on the concert stage. But it's still only a window. We're not in the concert hall, we're still just looking (or hearing) into it.
The acoustical space---the sound of the performing hall which is as much a part of live-music sound as the instruments themselves---is very audible on a good stereo system, but it's all on the other side of that window. Depth, too, stops at the window. While it is possible to reproduce an illusion of front-to-back perspectives behind the loudspeakers---and we must often cheat by calling on rear-wall reflections to help do it---there are no systems in existence capable of stable imaging in front of the loudspeakers. This is okay if all we ever listen to are conventional classical works in which the musicians all sit on a stage upfront, but if we try to reproduce such things as offstage brass choirs, or antiphonal works in which a choir or a group of instruments or a pipe organ were originally located behind the listening seat, it can't be done (footnote 1). All these will come from up front, inextricably mixed with the onstage sounds. There's only one way of breaking through the window and moving into the performing hall, and that is by using rear speakers to reproduce the ambience and other sound sources which surround and flank us when we sit in a real concert hall. It's called surround sound.
Reproducing ambience from a pair of rear-placed speakers does for depth what stereo does for direction: it draws the soundfield across the space between the pair of speakers---in this case, the front/rear pair. Image positions are no longer limited to the space behind the speakers, but can be located anywhere between the front and the rear wall of the auditorium---or the listening room. The effect is one of being surrounded by the hall; you're right in it. It's the ultimate reproduction of the original performing space.
And four-channel reproduction does more than just enhance the reproduction of space; it also improves the naturalness of musical-instrument sounds. Instead of receding layers of cardboard-cutout instruments, their sounds take on an almost palpable roundness and depth that make conventional stereo seem thin by comparison. So why doesn't every serious audiophile have a four-channel system? Because four-channel, also known as quad, has never lived down its reputation as the biggest marketing disaster in audio history.
Quad---short for quadraphonic---sound was introduced to consumers in 1970, not because its promoters were dedicated to advancing the state of the art, but because selling two more amplifiers and speakers and a new control unit to every stereophile looked like a great way to revitalize what was believed to be a stagnant audio market. But almost immediately, the industry started galloping off in several directions at once. A majority of record companies assumed that consumers didn't know or care about ambience, and used quad to place the listener in the middle of a circle of instruments, like a moose besieged by wolves. And the quad decoders were a disaster; they didn't separate the channels very well, and were loaded with every electrical distortion in the book. Add to that the fact that there were four "standard" quad systems---all incompatible---and quadraphony's demise was assured. Audiophiles learned early on to despise it, and the consumer in the street either didn't give a damn one way or the other, or refused to choose among the warring systems. Buyers stayed away in droves, and quadraphony was a dead issue by 1977. Even today, "that word" is one that few industry people will dare to utter. But the concept did not die; it just changed its name and went to the movies.
Footnote 1: When Decca/London released their landmark Das Rheingold recording in 1958, a judiciously worded press release by producer John Culshaw hinted that the careful listener would be able to hear, at the very end of the opera, the Rhinemaidens singing from below the soundstage. Critics and listeners alike, baffled by the impossibility of such an effect, nonetheless pointed out the phenomenon, asking in awed tones, "How did they do that?" In his 1967 book Ring Resounding, Culshaw revealed the source of the "technique": the self-fulfilling prophecies of well-placed PR.---RL