I am a little disturbed that my IB is louder behind the woofers.

Discussion in 'Home Theater Projects' started by James W. Johnson, Jul 5, 2004.

  1. James W. Johnson

    James W. Johnson Screenwriter

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    For those not familiar with my IB , its a dual 18" Blueprint 1804s (avail @ acoustic-visions.com).

    The 2 woofers fire into my HT room and the back of the drivers are facing into my living room/kitchen etc.
    The area behind the drivers is indeed bigger than the the area in front of the drivers.

    Why is it so much louder behind the drivers? Now I really noticed this one day last week when I had the front and back door open but I am not sure if this was related or not.

    Maybe I should just turn the drivers around eh? [​IMG] [​IMG]
     
  2. Cam McFarland

    Cam McFarland Supporting Actor

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    Can't answer your question, but thanks for giving me your address.

    Now, when do you leave for work...??? :wink:

    [​IMG] [​IMG]
     
  3. James W. Johnson

    James W. Johnson Screenwriter

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    Come on over, my friends will keep you company. [​IMG]

    [​IMG]



    ...and when I do get home from work I'll take over from there. I used to shoot about 2000 rounds month thru my pistols to keep my edge. We will have a little target practice in the back yard. [​IMG]
     
  4. Jason Dalton

    Jason Dalton Stunt Coordinator

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    How about switching the phase...
     
  5. ThomasW

    ThomasW Cinematographer

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    James,

    The same amount of sound comes from the front and the back of the drivers. Any differences you're hearing are a function of the room and or the construction.

    Given how loud the output levels were that you posted on HTT I fail to see why this is an issue.
     
  6. James W. Johnson

    James W. Johnson Screenwriter

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    Hi Thomas its definately not an issue , its more the control freak in me that is bothered that the room outside my HT room has more bass...although the bass inside sounds cleaner so I guess I should be happy its not the other way around. [​IMG]

    Well thanks for the explanation though, I was thinking that it might be because the space on either side of the woofers is so different.
     
  7. Cam McFarland

    Cam McFarland Supporting Actor

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    That was just a little "heads up", James.......[​IMG]

    I see its gone now.
     
  8. Geoff L

    Geoff L Screenwriter

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    Dumb question time:

    What would happen if he turned only one aroud and then wired them out of phase with each other?

    I know it's an IB, but would not the same laws apply like in a push pull with output not supposedly affected, just the sound possibly just slightly cleaner...
    The IB box, or house room encloser being so large maybe this might not apply to the extent in would in a coventinaly PP-design.
    Dumb question maybe, but always curious!
    Or for shizt and giggles, turn both around and re-measure the FR at the same approxment spl level and postion..

    Bottom line:
    Given the numbers posted in the major feel it area, my god a house inspection might be called for to make sure the structure is still safe!

    Best I've heard in house, is 14hz at a clean wimmpy 98-99db, can olny imagine 120db plus at 10Hz!

    SICK, but a very cool I want one SICK...~{[​IMG]}~
     
  9. ThomasW

    ThomasW Cinematographer

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    Goeff

    Reversing one driver would slightly decrease the harmonic distortion (probably not audible, but could be measured with good test gear). It would have no impact on the actual output level.
     
  10. Geoff L

    Geoff L Screenwriter

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    I figured that most likely there would be little or no difference doing that due to the size of the encloser. Aside from high tech measuring gear....

    But mounting them back wards (magnet out and wiring both drivers out of phase) might be interesting, and certainly a conversation piece.
    Performance wise, now that would/could/might be a very diffrent thing.
    Good, bad, or indifference..?

    Would have to re-measure SPL/SQ the same exact way he did with the conventional IB-mount he's using now. Might be an interesting test anyway.
    Being he likes to tweek/play around/be sure it's getting/giving all it can, might be worth a the effort if he dose not mind the major weight lifting excercise..!

    Then most likely, they would have to go back as they were, BUT now he knows for sure that front/forward firing into the HT-room is/was right to begin with...[​IMG][​IMG][​IMG]

    Very awsome anyway you look at it, dual 1804's doing IB duty, as my nephew would say, thats neato man....!

    Regards
    Geoff
     

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