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Easy question: About port tuning

Discussion in 'Subwoofer Box and Custom Fabrication' started by subkiller, Aug 18, 2008.

  1. subkiller

    subkiller Full Member

    subkiller, Aug 18, 2008
    #1
  2. aznboi3644

    aznboi3644 Full Member

    get a picture up of your enclosure.

    What do you mean what size port??? What kind of enclosure is it??
     
    aznboi3644, Aug 18, 2008
    #2
  3. subkiller

    subkiller Full Member

    I dont have a camera handy right now, but the box design is similar to the one shown here http://kollmanradio.com/images/db212.jpg
    The currnet port is a slide in made of 3/4 inch mdf, rounded edges, the port measures 7" H x 4" W x 9" D
    I am trying to find out the proper port size for a decent sounding tune.
     
    subkiller, Aug 18, 2008
    #3
  4. fstrfvo

    fstrfvo Full Member

    Why dont you contact MMATS and ask them for the specs that go with those speakers.
     
    fstrfvo, Aug 19, 2008
    #4
  5. subkiller

    subkiller Full Member

    Oh, I have the specs for the mmats. Recommended box size is 2.0 cu.ft (per speaker) but the port recommended has me confused. It recommends a port of 20 sq. inches x 15" L
    I don't know how to figure that out. Would it be 5" x 4" and 15" long?

    Could I mix it up and make a port 2" x 10" and 15"L or can I vary the dimensions with the length? The port thats in it now is 7" x 4" x 9"L
     
    subkiller, Aug 19, 2008
    #5
  6. Ranger SVO

    Ranger SVO Full Member

    Yes and no

    The port needs to be 15-inches long, the opening can be 2-inches by 10-inches or 4-inches by 5-inches or any cross sectional area that gives us 20 inches squared.

    Now for the 7" x 4" x 9"L, We need a little more info, what frequency do they recommend the box be tuned to.

    Your box that measures 35 W x 20 H x 13 D is about 4.1 cu. ft. A 6-inch round port tuned to around 36 to 38 Hz would need to be about 9 inches long. So your 7" x 4" x 9"L, (which is similar to my 6-inch) might work if 36 to 38 Hz is the right tuning. Now my estimate assumes that your box is one large box with no divider in it.
     
    Ranger SVO, Aug 20, 2008
    #6
  7. subkiller

    subkiller Full Member

    I should make the port the same size as they recommend. You are right in guessing that the box is a single enclosure, no divider. I forgot that the recommended port would actually need to double in size, because the specs are for one single sub. So, does that mean I need a port 10" x 8" x 30"L ? Or two ports that are 5" x 4" and 15"L. I am a tad confused, my brain just cannot wrap around this. They don't list a recommended tuning frequency for these subwoofers. I have the spec sheet for them, perhaps theres a way to figure out the proper frequency from those figures?
     
    Last edited: Aug 21, 2008
    subkiller, Aug 20, 2008
    #7
  8. tyrant1014

    tyrant1014 Full Member

    Listen to the ranger... he knows his stuff, because he does. :D
     
    tyrant1014, Aug 21, 2008
    #8
  9. subkiller

    subkiller Full Member

    I know I'm a pain in the a**, but I really need the last question answered. Do I build a port thats 30" L, or do I add two ports?:confused:
     
    subkiller, Aug 21, 2008
    #9
  10. Ranger SVO

    Ranger SVO Full Member

    OK, lets do this. Your box that measures 35 W x 20 H x 13 D is perfect for porting. Use NO divider, both woofers should share the same air space. A single 6-inch round port 9-inches long should work. Your 7" x 4" port will also work at 9" long.

    I will post a slightly different box idea in a few minutes
     
    Ranger SVO, Aug 22, 2008
    #10
  11. subkiller

    subkiller Full Member

    thanks ranger, how can I bring the hz down to around 34?
     
    subkiller, Aug 22, 2008
    #11
  12. Ranger SVO

    Ranger SVO Full Member

    I really like 6-inch round ports, it works s well for many applications. The problem is finding PVC that size. Our local Lowes carries 6-inch PVC.

    A slightly smaller box would measure 13"H x 34"W x 18"D. A 6-inch round port around 10-1/2-inches long would work well. Again NO divider, both woofers should share the same space.
     
    Ranger SVO, Aug 22, 2008
    #12
  13. subkiller

    subkiller Full Member

    sweet! time to make a plug for the current port hole, then I'm off to lowes. Thanks Ranger! Preeshiyadit.
     
    subkiller, Aug 22, 2008
    #13
  14. Ranger SVO

    Ranger SVO Full Member

    The box would need to be larger, go with 36"W x 14"H x 18"D, Now the 6-inch diameter port would need to be about 11 to 12 inches long.
     
    Ranger SVO, Aug 22, 2008
    #14
  15. aznboi3644

    aznboi3644 Full Member

    Mmm....I love big ported enclosures
     
    aznboi3644, Aug 23, 2008
    #15