Port noise

Discussion in 'Archived Threads 2001-2004' started by Frank Kanyak, May 15, 2002.

  1. Frank Kanyak

    Frank Kanyak Stunt Coordinator

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    Is there any solution to control my port noise at during some intense scenes. I did do a search in the DIY to no avail. It sounds like a chuffing like someelse said. ^' port x 26" length.
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    26" is pretty long, is there a shorter length alternative?

    Are your ports flared? I found that my two 11" flared ports create no noticeable air noise. (Unless I run a test tone and listen close to the ports)
     
  3. Greg Monfort

    Greg Monfort Supporting Actor

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    You can stretch grill cloth (or similar) over the vent, turning it towards Aperiodic. Peak vent output will drop a little. If one layer isn't enough, then try two, but the main thing is getting it tight. Once you have the right amount, make a frame to attach it to, and to the sub.

    BTW, this improves transient response too, though how audible it will be I can't say.

    GM
     
  4. Ron Shaw

    Ron Shaw Stunt Coordinator

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    Port noise is caused by the port area being too small. The velocity in the port should be kept below Mach .2 in order for port noise to be inaudible. Increase the area (diameter) of your port. You will need to increase its length to keep the tuning the same.
     
  5. Dave Poehlman

    Dave Poehlman Producer

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    Is it a DIY sub, Frank?

    Flaring the port may help. Widening or doubling your port will definately help. As stated above.. you would have to rethink the length of your port(s) if you want to keep the same tuning.

    If it is a DIY sub and you are using PVC pipe.. make sure the ends are cut smooth.. sometime a burr or rough cut can cause noise.
     
  6. Patrick Sun

    Patrick Sun Moderator
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    I'm guessing Frank is using 6" wide port. That should be wide enough.
     
  7. Brian Bunge

    Brian Bunge Producer

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    Pat,
    So how was the movie! [​IMG]
    Brian
     
  8. Dave Poehlman

    Dave Poehlman Producer

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  9. Patrick Sun

    Patrick Sun Moderator
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  10. Frank Kanyak

    Frank Kanyak Stunt Coordinator

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  11. Greg Monfort

    Greg Monfort Supporting Actor

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    Well, you can stick a longer 6" tube in, but it'll probably need to be ~45" long to be effective, or you can double up or stick a larger one in, which will make it (them) even longer. Not good plans IMO, so this leaves either my suggestion, a combination of my suggestion and make it a little longer, or seal it up.

    GM
     
  12. Frank Kanyak

    Frank Kanyak Stunt Coordinator

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    If I redo my endcap(meaning not having a port) will it play louder and deeper or just the opposite?
     
  13. Greg Monfort

    Greg Monfort Supporting Actor

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    Just the opposite unless you accept the higher distortion of increased excursion, though frankly it will be low enough in frequency that overall it may sound better.

    GM
     
  14. Patrick Sun

    Patrick Sun Moderator
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    The opposite.
     

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