Speaker type for 7.1 rears?

Discussion in 'Archived Threads 2001-2004' started by Kevin C Brown, Nov 11, 2002.

  1. Kevin C Brown

    Kevin C Brown Producer

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    There's another thread in the receiver/separates section, but it ended up to be more about wiring 2 speakers in series or parallel for 7.1 with 6.1 channels of amplification.
    Anyway... [​IMG]
    I have direct radiators for the front 3, bipolars for the surrounds. What should I do for the rears? Dipoles? Or direct radiators? For a THX Ultra2 or Logic 7 type setup (non-mono rears). I'm kind of limited in that the speakers will sit on a sort of shelf thing that's on top of my desk back there. So there won't be much space between them and the back of the shelf.
    The front L + R and the surround L + R are (more or less) full range towers, but I cross them over anyway. The rears will have to be bookshelf size.
    Thanks!
     
  2. Phil_DC

    Phil_DC Stunt Coordinator

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    Most people seem to be happy with direct radiators for their rears mostly because they produce a sound that their used to hearing. I myself have tripoles for sides and dipoles for rears, my ears like that setup the best. Your best bet is to just listen to both with same material and see for yourself.
     
  3. Kevin C Brown

    Kevin C Brown Producer

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    I have a set of dipoles I can try... But no direct radiators for comparison.

    I was thinking about those Cambridge Soundworks speakers that are selectable, but I want them to sonically match my surrounds, which are Def Tech...
     
  4. LanceJ

    LanceJ Producer

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    Bipolar/dipolar--->I can't remember which is which-sorry!-but I do know this: one of these speakers has what's called a "null zone" (i.e., no sound output) to aid in preventing listeners from identifying where it's located. That null zone is opposite the speaker's mounting surface.
    Soooooo, if a speaker of this variety is used as a back surround, & this null zone is "pointed" at the listening area, the people within, say, a @45 degree angular area will hear little to nothing, negating the entire advantage of having that back channel there in the first place.
    And many dipole/bipole speakers use an asymmetrical driver configuration. In other words, one side will have a woofer & tweeter, the other will use just a single tweeter or mid-tweeter. This would cause really weird & irritating sound effects the movie director never intended!
    Personally, I would stick to a direct radiator with wide sound dispersion characteristics (speakers with ribbon tweeters are very good at this) or a single DefTech bookshelf-sized model, facing into the room normally.
    LJ
     
  5. Kevin C Brown

    Kevin C Brown Producer

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    LJ- Thanks! You're right: it's dipoles that have the "null zone".
    OK, 3 votes for direct radiators, none for dipoles.
    I do think this matches up with what is recommended for L7 and THX Ultra2 anyway. Just took me a little while to remember... [​IMG]
     
  6. Wayne McRae

    Wayne McRae Stunt Coordinator

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    Kevin, I tried a pair of bipolar Def-techs for the rear 2 speakers and got poor results. I have a pair for the sides, which work great, but I found that directs work the best. Cue up Gladiator and go to the chapter: A soldiers death. About a minute in, Crowe throws a sword and if using directs it sounds like the sword flies thru your hair. Using the bipoles it sounded to diffused and not as clear. Hope this helps.
     
  7. Kevin C Brown

    Kevin C Brown Producer

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    Thanks Wayne.
     
  8. Jeff Adams

    Jeff Adams Screenwriter

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    Kevin, I would definately go with direct radiators. Just like Wayne I have a semi bi pole design for my sides and direct radiators for the rear. I can't imagine ever watching a movie again without them. The first scene in Episode II where the ships fly over is amazing. I watch that scene over and over again.
     
  9. Kevin C Brown

    Kevin C Brown Producer

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    Hey, let me ask another question since this thread seems to be surviving:

    timbre matching, or flat freq response?

    Do I get more Def Techs to match the BP-30's I'm using as surrounds now? But I have seen 3 reviews of Def Tech ProMonitors and Studio Monitors and the BP2X, where the freq response graphs have somewhat of a spike around 13-14kHz.

    Or, do I go with something like B&W, Axiom, Paradigm, Phase Technology (among others) where I've seen flatter freq response curves?

    I'm tending towards the latter simply because I don't want to compound any problem the BP-30's might have. (They all have the same 1" Al tweeter.) But I am shooting for at least the same size tweeters and woofers as the BP-30's: 1" and 6.5".
     

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