sealed Tumult bottoms during matrix

Discussion in 'Home Theater Projects' started by Brad Dixon, Sep 4, 2003.

  1. Brad Dixon

    Brad Dixon Stunt Coordinator

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    It's a 115-120 liter sealed enclosure with the keiga 1000w amp. I set the level using rs spl meter and avia. I don't have a bfd yet or taken any room measurements really. The sub sounds great except on the scene in the Matrix where the helicopter crashes into the building. It makes some noise, a wop/clack sound. It doesn't sound like I remember a car sub bottoming but that's all I can think of. This is the only movie that causes this.

    Is it possible it could be a small air leak? According to Unibox 4 it would take 13hz or lower with 1000w to bottom it. Or could it possibly be the amp clipping even?

    Thanks,
    Brad
     
  2. David Giesbrecht

    David Giesbrecht Second Unit

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    I would say its probably the amp clipping at that point, air leeks usually don't cause enough noise for you to hear it when the SPL's are that loud. Does the sub look like it's working really hard? More power might be the answer here.
     
  3. Kyle Richardson

    Kyle Richardson Screenwriter

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    Sounds like it could be the amp clipping which can sound like the clacking of a bottoming driver. Do you have the 25Hz boost on? If so, you'll run out of headroom a lot quicker than if it was off.
     
  4. Seth_L

    Seth_L Screenwriter

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    Hmm... I have 2400W on tap and haven't been able to bottom the driver yet. I have slightly clipped the amp though.
     
  5. Brad Dixon

    Brad Dixon Stunt Coordinator

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    You guys were right, it appears to have been the amp clipping. I did have the 25hz boost on, when I turned it off I didn't hear the noise during that scene.

    After having this thing a bit now, I'm still undecided if I should have went with 150L with dual PR's for even more impact on movies.

    I don't think I need more output but I enjoyed building this box with my father and am trying to decide on another project we can do.

    Thanks,
    Brad
     
  6. Kyle Richardson

    Kyle Richardson Screenwriter

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    Uh, oh. Another has fallen to the dark side[​IMG]
     
  7. David Giesbrecht

    David Giesbrecht Second Unit

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    MORE POWER!

    Its a good thing[​IMG]
     
  8. David Giesbrecht

    David Giesbrecht Second Unit

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  9. Wayne Ernst

    Wayne Ernst Cinematographer

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  10. Brad Dixon

    Brad Dixon Stunt Coordinator

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    OK this is going to sound dumb but what exactly will more do for me? I'm planning on buying a BFD and getting the response as flat as possible with my current sealed Tumult and matching the levels of my mains. As it is(may change after getting the response flattened out?) my ears reach their limits before the Tumult does.

    When it was making that noise it was at high volume while friends were over wanting to check it out. There is hardly any possibility of it being at that level while actually sitting down and watching a movie with my wife and boy.

    Another project with my father would be fun and I'm just trying to decide if I want it to be another sub enclosure or something else.

    Brad
     

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