Port size for my sub?

Discussion in 'Archived Threads 2001-2004' started by Bruce Chang, Jun 14, 2002.

  1. Bruce Chang

    Bruce Chang Second Unit

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    Ok I built a 18W x 24H x 12Depth externally 3 cu ft box made out of 3/4 MDF and put double the MDF on the front of the box, so about 16.5W x 24H x 10.5 internally 2.4 cu ft. This is for my Illusion Audio nd 15 subwoofer and is currently sealed. I need to port it for more bass output, but don't know what size port I need. Here's the specs it's near the bottom
    http://www.solen.ca/ill.htm
     
  2. Jeff Rosz

    Jeff Rosz Second Unit

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    tough build , bruce.
    problem is fitting a port in that size box with those dimensions. unless you have no objections to porting it out the top (whats the depth of that driver?), in which case you could get a decent port to work. if not you are looking at a higher tuning frequency and some port noise.
     
  3. Bruce Chang

    Bruce Chang Second Unit

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    My friend top me to use two 30inch long 3 inch diameter port tubes coming out from the top which would look like rabbit ears. Don't know if he's right or not. I just wanted to hear from others before I do it. Here's the manufacture specs
    http://www.illusionaudio.com/illusion/Technologyx.html
     
  4. Jeff Rosz

    Jeff Rosz Second Unit

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    yikes, when i said "port it out the top" i meant have the port totally inside the box and exit flush with the top.
    how bout one 4"x20" to give an Fb of 26hz?
     
  5. AlexKunec

    AlexKunec Stunt Coordinator

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    How much do those nd15's cost? They seem to have pretty good specs. Also it claims to have 1.5" xmax. Would that be one way?
     
  6. Bruce Chang

    Bruce Chang Second Unit

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    Jeff, won't I get port noise when it's 4x20?

    Alex, I forgot how much I got mine for.
     
  7. Bruce Chang

    Bruce Chang Second Unit

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    Oh Jeff my friend was using winisd, what program where you using?
     
  8. Jeff Rosz

    Jeff Rosz Second Unit

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    i am using bassbox. sure you can get port noise, but looking at the power curve you wont want to apply its full rated 600w in this box. more like 250w is a more reasonable number. at 250w input power the vent velocity never goes over 20m/sec in its BW. you could get a longer port by using an elbow for an L shaped tube with a total length of about 28-30". unless you want the stovepipe look, use any vent you want.
    imo, this box is choking that driver, you arent getting anything near its potential. build a larger box.
     
  9. Bruce Chang

    Bruce Chang Second Unit

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    Well I dual ported my existing sub box and it sounds great in my room. I'm very impressed on the way it sounds eventhough it's kind of ugly. The great thing is that I have no port noise thanks to the 3 dia 30 inch long ports.
    pic here
    http://community.webshots.com/storag...3ibjyKY_ph.jpg
     
  10. Neil Joseph

    Neil Joseph Lead Actor

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    Real Name:
    Neil Joseph
     

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