Listening position against back wall...

Discussion in 'Speakers & Subwoofers' started by David Smith, Jul 16, 2003.

  1. David Smith

    David Smith Stunt Coordinator

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    If my listening position is completely against the back wall of my small room, and I have no way of moving this position out from the wall, is it better to leave the wall alone or to have some acoustic foam or something right behind my head?

    I already have acoustic treatments at the other mirror points, etc.

    Also, I’m talking about mostly music here, and not HT.

    Thanks!
     
  2. Terry Montlick

    Terry Montlick Stunt Coordinator

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    Hi David,

    If you've already treated the other mirror points, and you're close to the back wall, you'd do well to treat that area as well.

    Ordinarily, you wouldn't have to worry too much about the rear wall. That's because the sound bouncing off it would be greatly attenuated compared to the direct sound. It falls off as the square of the distance, as reflected off the wall.

    But the closer you get to a rear wall, the less attenuated it will be. If the direct sound were 10 feet in front of you, and a perfectly reflecting rear wall were one foot behind you, then the reflected sound (12 feet between you and the speaker) would only be around 3 dB down.

    And the closer you are to the wall, the closer the time is between the direct sound and the reflected sound. If you are one foot from the rear wall, and figuring sound traveling at about one millisecond per foot, the reflection would come at around 2 milliseconds. That's well within the 15 millisecond "problem window" which can effect accurate front imaging. And accurate front imaging is the reason for treating the mirror points to begin with!

    Regards,
    Terry
     
  3. David Smith

    David Smith Stunt Coordinator

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    Terry,

    Thanks so much for your reply. As much reading as I've done on acoustics, and as much time as I've spent searching for answers, I just couldn't find anything about this specific circumstance in regards to the rear wall.

    Anyway, thanks again for your reply! David
     
  4. Chris Xolotl

    Chris Xolotl Second Unit

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    absorbers directly behind you on the wall and diffusers to the sides of that on the rear wall as well.

    i moved my RR and RL speakers two feet off the back wall and my listening couch about the same distance off the back wall.

    the results were nothing less than AMAZING. no upgrades, nothing, just moving
     

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