Why from 5.1 to 6.1 to 7.1 - Where's 8.1?

Discussion in 'Archived Threads 2001-2004' started by Lin Park, Jan 25, 2003.

  1. Lin Park

    Lin Park Second Unit

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    I understand going from 5.1 to 6.1 by adding a rear center, but why was the rear center abandoned when the manufacturers went to 7.1? Wouldn't it have made more sense to go with 8.1 by adding two side speakers to the 6.1 configuration or were they simply trying to keep the upgrade paths coming?

    I know the rear center was a matrixed configuration but I'm guessing that in another few months we'll be seeing these 8.1 upgrades coming out. What does everyone else think about this?

    Lin
     
  2. Michael Reuben

    Michael Reuben Studio Mogul

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    Seven-speaker setups predate the arrival of Dolby Digital EX and DTS-ES by several years. (The magic word is "Lexicon".) Most of the current setups commonly called "7.1" grow out of THX's recommendation for Surround EX that the rear center be sent through two separate speakers. Receiver manufacturers like to call it "7.1", because they think in terms of channels of amplification, but it's not really a meaningful (or accurate) notation.

    Only with Logic7 is there different information sent to the left and right rear back speakers, courtesy of fancy DSP. Otherwise, the configurations labeled 7.1 are really no more than 6.1 at best.

    M.
     
  3. Phil*K

    Phil*K Stunt Coordinator

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    Lin,

    Actually there is 8.1 already, but you have to buy Yamaha. The RX-V1, RX-Z!, and RX-V3300 all have two front effects speakers In addition to their normal 6.1 setup.

    Phil
     
  4. Kevin C Brown

    Kevin C Brown Producer

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    There is a psycho-acoustical effect called "reversal". When the human brain hears a sound directly behind it, it *sometimes* can get confused and localize that sound to the front. It's rare, but it does happen. With 7.1, by using two rear speakers instead of just 1 as for 6.1, the effect is greatly minimized.

    Also, having 2 speakers back there decreases the chance of localization over just 1, just because there are now 2 point sources and not just 1. For example, for 5.1, it is recommended to have dipole surrounds to lower the chance of localization. But, when you go to 6.1 and then 7.1, just the fact that you have more speakers back lowers the chance of localization so much that it is now *some* people's recommendation that you can use monopoles for all 4 speakers. Better imaging is the primary benefit.
     
  5. Philip Brandes

    Philip Brandes Stunt Coordinator

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    And Meridian--they've also supported a 7.1 speaker configuration for years. It's interesting that these two companies, who are at the forefront of surround decoding technologies, both came to the same conclusion about the number of speakers needed for seamless immersion, a conclusion since ratified by THX, Dolby and DTS.

    Cheers,
    Philip Brandes
     
  6. John Garcia

    John Garcia Executive Producer

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    I don't know if you noticed, but 7.1 is an even number of speakers: 6 (sub tecnhically does not count). 7.1 ALREADY has 2 side surrounds and 2 rears...
     
  7. SvenS

    SvenS Second Unit

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  8. AhsanR

    AhsanR Stunt Coordinator

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    Is 7.1, really worth it?

    I really want 5.1, but if 7.1 is really worth it, I will plunk down the extra money.
     
  9. Kevin C Brown

    Kevin C Brown Producer

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    Ahsan- If you have the space and the denaro, I say at least *try* 7.1. If you don't like, you can always go back to 5.1. But I've never actually heard of *anyone* who's tried 7.1 and *not* liked the improvement in the rear soundstage that results. [​IMG]

    Sven- The problem with putting the rear surround speaker up high enough to eliminate reversal, is that now you are *under* the sound field, and not *in* it.

    I found this out when I switched from 5.1 with dipole surrounds the recommended 30" higher than ear level, to towers *at* ear level. For example, instead of feeling like I was *underneath* the action in the 1st 20 min of Saving Private Ryan with the dipoles, I felt like I was *in the middle* of the action with the towers.
     
  10. AhsanR

    AhsanR Stunt Coordinator

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    I'm worried I'm gonna blow my money, and as of right now, I'M ON A BUDGET..... thats why I am very VERY hesitant in purchasing.

    I'm new to HT, so tell me something, how often are the rear channels used?
     
  11. SvenS

    SvenS Second Unit

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  12. Philip Brandes

    Philip Brandes Stunt Coordinator

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    Sven,

    Reversals can occur at any point along the median (center) axis equidistant between the ears; elevating a single rear speaker does not solve the problem. Using more than one rear speaker, however, does--which is why Dolby, THX, and dts all take that approach.

    Cheers,
    Philip Brandes
     
  13. Dave Moritz

    Dave Moritz Producer
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    I could go for 8.1 if it was in the configuration like SDDS is in. I am not a big SDDS fan but the idea of dual center channel is nice. IMHO this would work really nice for projection setups with 110" + screens [​IMG] .
     
  14. Kevin C Brown

    Kevin C Brown Producer

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    Sven- I have had the surrounds up high. I've had them at ear level. I much prefer the sound I got at ear level. The speakers were a little bit more localizeable, but I preferred the greater amount of detail that results. Although now I have them all about 1 ft above ear level. This seems to be the consensus for the best placement for Logic 7 and for THX Ultra2. (The detail is still there, and because the angle to my ears at the best listening position is still less than 15 deg, I don't get much high freq rool off. See below. But helps with localization.)

    I agree, the *old* recommendation for DPL was surrounds up high, because the content in the surrounds was almost exclusively ambient material. But now with DD/DTS/DD EX/DTS-ES where there is now a lot of actual discrete steering within soundtracks, the "recommendations" that I have seen have slowly changed to encompass that, and that is to lower the surrounds.

    Ever see an off-axis freq response from any speaker? The highs get major-league rolled off.

    If you ever have a chance, I recommend you try it. [​IMG]

    Oh yeah, in one of the reviews in the Jan SGHT, I was actually really surprised that one of the reviewers mentioned that *he* thought the best sound in his room was with all monopole surrounds/rears at ear level. And? That is without a doubt the best setup for multichannel music. Kind of neat that it works well for HT too.
     
  15. SvenS

    SvenS Second Unit

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  16. Kevin C Brown

    Kevin C Brown Producer

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  17. SvenS

    SvenS Second Unit

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  18. Martin Rendall

    Martin Rendall Screenwriter

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    AhsanR,

    I'd say not, if you are on a budget. I have 7.1, but I only use the rear two for movies encoded for a rear center. Sure, it sounds better than 5.1, but not the cost of two matching speakers and an amp better. IMHO, 7.1 is *way* into the deminishing returns curve.

    Martin.
     
  19. Kevin C Brown

    Kevin C Brown Producer

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    Hey Sven, let's see if you can understand, one more time:

    1 ft above ear level is still above rear level.

    And, 1 ft above ear level, is still *lower* than the old recommendation of 2 - 3 ft above ear level.

    Got it? That's exactly what I wrote, and that's exactly what I meant, no matter how many times you reference "Dolby Labs" in a sentence with exclamation points.

    I said I had *tried* tower surrounds with the tweeters at ear level, that I preferred the sound vs dipoles way up high. And I mentioned the SGHT review where the reviewer also echoed that same sentiment. I never said that tweeters at ear level were an official recommendation by anyone. Please reread my posts again if you are confused.
     
  20. Sacha_C

    Sacha_C Second Unit

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    "I don't know if you noticed, but 7.1 is an even number of speakers: 6 (sub tecnhically does not count). 7.1 ALREADY has 2 side surrounds and 2 rears..."

    The ".1" is the sub, the "7" is the number of speakers, there are 7 speakers + 1 sub in 7.1
     

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