Originally Posted by DS-21
Let's assume arguendo
your 90% figure is true. It's still the answer to the wrong question.
The relevant and material question is not
"how much content is back there?" Rather, the important question is "how discerning is the human auditory system to differences in spectral balance and location cues in the rearward hemisphere, compared to the front hemisphere?"
The answer to the question that matters is, in short, "not very."
The Absolute Zero may be a bit light for some uses, depending on the size of the room, but it is a speaker with wide and fairly even horizontal dispersion.
Dr. Floyd Toole makes some interesting recommendations for surrounds, too. Here's how he starts 18.4.4, which he titled "The Perfect Surround Loudspeaker"
"A very wide, uniform horizontal directivity pattern is needed to provide the localization cues for directed sound effects and to establish the basis for the perception of envelopment. Conventional forward firing or bidirectional in-phase on-wall loudspeakers are eminently capable of delivering those experiences, but excellence is guaranteed only for the central seating area. As listeners move toward the sides, sounds arriving from the nearer loudspeaker get rapidly louder, and those from the opposite loudspeaker get quieter. The sense of envelopment is progressively diminished, and it eventually disappears, replaced by sound emerging from the nearby loudspeaker. Figure 16.8 explains the cause— propagation loss—and proposes one solution: full-height line-source loudspeakers. However, as good as they may be, for reasons of size and cost they are not practical solutions for the mass market. A target performance for “the perfect surround” loudspeaker was also proposed: a loudspeaker with, in effect, no propagation loss."
Toole, Sound Reproduction,
It's worth noting what is completely absent
here, or elsewhere in the book: any reference to the surrounds "matching" the mains in any way.
I've considered buying a pair of the smaller JBL CBT speakers (the ones with 8 or 16 2-inch drivers) to see if they are indeed an improvement over the standard "concentric driver firing up" approach that I've consistently found to offer the best compromise thus far.
That is also my experience. A while back now (2005 or 2006) I spent a fair bit of money to upgrade my side and rear surrounds. My previous surrounds were KEF Q-Compact speakers, which were solidly in the good-not-great category. On the plus side, they had wide and even dispersion in the midrange, though some audible flaring in the penultimate octave (5-10 kHz). On the minus side, when used as front speakers they sounded nasal, and with just a 5" concentric driver they couldn't go that loud. Their replacements used Tannoy 8" Dual Concentrics and were very similar to the front three speakers. (The front three speakers did use Tannoy's "next level up" 8" concentric driver, in stouter cabinets.)
I eagerly cued up my multichannel SACD's and DVD-A's. (I'm more a music guy than a movie guy - honestly, I'm not sure I've ever intentionally planned to re-watch a movie.) The result was..."really, that's it?"
I was so puzzled that I put two of Q-Compacts up front, turned off all processing, and listened in stereo. Sure enough, they sounded rounded off compared to the Tannoys, and nasal. The highs sounded slightly less natural too. Then I tried the Tannoys I bought to replace them, crudely level-matched (the Tannoys were considerably more efficient), and they were just much much better all around.
Since then, I haven't much cared about surrounds. I do prefer surrounds that are more-or-less similar to the mains, but on aesthetic rather than functional grounds.
"Matching" is a BS marketing conceit with no basis in reality. (Unless one's talking about a cosmetic
In the real world, there is "identical," and there is "not identical." If some marketer says "matched" on its own or paired with some adjective such as "voice" or "timbre," one can intepret that word/phrase simply as "not identical."The front three mains should be identical, if at all possible.
("Identical" here meaning same speaker, same height, same orientation.) Speakers to the sides and rears need not be identical.
To make sure I understand you correctly, you feel that it is marketing hype and NOT a performance consideration as to why people voice match their surrounds?
Let me attempt to use real world, practical example as to why I disagree....
I consider the entire room to be the "stage". The idea of front stage, rear stage, side, etc. is a little strange to me because the idea for a multi-channel system, to me, is to immerse yourself into the film's "stage" in it's entirety, so to speak. Now, I will often refer to the "front stage" as such because it's easier to do when speaking on the front three speakers but, other than that, I refer to multi-channel rigs as complete systems.
I find it incredible to believe that people feel there is a definite, indisputable, difference in interaction between Left, Center, Right to the point where they DEFINITELY must match those three speakers but... the sides and rears... not so much.
Using this image as an example:
For practical purposes, there is similar distance between the seating position and the front left & right, and the left & right surrounds. There is not some gaping chasm of space that is so different (only a few feet for most rooms - and sometimes, not even that) that there is such a separation that the listener cannot tell a difference in voicing.
Does that make sense what I am trying to explain? It definitely would be easier to show in an actual room. If there is (say) 10' between the Front Left and center, and then maybe 15' between the Front Left and the Left Surround, how can one need to be voice matched and the other not? The difference in space and timing is virtually identical, so why does the rule change? Even if the surround was 25', 30', 40' from the mains, this should not be considered very far in comparison at all because of the speed of which sound transfers and is mixed in the content.
There is a tremendous amount of content now that is mixed for multi-channel that uses the rear surrounds heavily. Even ambient sounds like crowed noise, soundtrack overlays, etc. will simultaneously come from front left, right, and surround left, right.
I disagree with the idea of fronts match, surrounds don't because of the reasons I listed above.
But, you don't have to believe me (ask Billy F, I'm just some guy on the internet
)? But, you can definately believe Dolby, they invented the stuff. I will paste the section #15 below, but here is the entire link for people who care to dork out and read it all
: http://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/42_DDFAQ.pdf15. What kind of
speakers should I get for
an all-new Dolby Digital
The ideal Dolby Digital
playback system would use
identical full-range speakers for
the left, center, right, and each
surround channel. If this is
impractical, be sure that the
overall tonal characteristic, or
timbre, of all the speakers is
similar. This is equally important
for both Dolby Surround Pro
Logic and Dolby Digital playback.
I find part of their statement about full range and then what they say in section 16 to be contradictory to another one of their published Dolby AC3 papers I have read through (about 53 pages) that discussed the detriments of having full range speakers crossed over below 80hz. What that paper said completely made sense so, I will have to research this some more.