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Need advice on port size and length

Discussion in 'Subwoofer Box and Custom Fabrication' started by dsjacr, Feb 3, 2012.

  1. dsjacr

    dsjacr Member

    Hi,
    I have 3-8" Pionneer TS SW841D's installed in a sealed common enclosure with .744 cubic ft with woofer displacement figured in @ .04 cubic ft each. The box is wedgeshape behind the seat of my 09' double cab Taco. I chose not use dividers due to the limitations behind the seat after the amp is mounted. My question is whether or not it can be ported? At low volumes it sounds ok but gets muddy at higher volumes with or without polyfil. I am running a kicker 500.1 with all the 4 ohm subs wired in parallel. A 2 or 3" diameter port is my best choice with a length up to 25" possible. 34-36 hz would beI great if possible. Thanks for any help.
     
    dsjacr, Feb 3, 2012
    #1
  2. dsjacr

    dsjacr Member

    According to the 12volt.com for 36hz the 2" port would need to be 7.33 inches long. I would think that the speakers actual technical specs would need to be factored in? But what do I know? Lol
     
    dsjacr, Feb 4, 2012
    #2
  3. Ranger SVO

    Ranger SVO Full Member

    Port tuning has nothing to do with the speaker. We only need the box size.

    Also .75 cu ft is way to small for a ported box, a 2-inch port is also to small because at tuning frequency the port makes the majority of the sound.

    Finally, how low we can play has to do with box size more than tuning. For example, a 2-cu ft box tuned to 40 Hz will play much lower and sound MUCH better than a 0.75 cu ft box tuned to 32 Hz. The graph below shows what happens, ignore anything below the -3dB point, its the begining of rolloff.

    The blue line is the 2 cu ft tuned to 40HZ
    The yellow line is a .75 cu ft box tuned to 32Hz

    (for this speaker neither box size or tuning is correct, just examples for you to see)
     

    Attached Files:

    Last edited: Feb 4, 2012
    Ranger SVO, Feb 4, 2012
    #3
  4. dsjacr

    dsjacr Member

    The reason I bought the subs was because they required very limited air space. Sounds like I will be building another box! LOL !Thanks
     
    Last edited: Feb 7, 2012
    dsjacr, Feb 7, 2012
    #4
  5. dsjacr

    dsjacr Member

    Even if the recommended ported box volume is 0.40 cubic ft. from Pioneer with a 2.5" x 6"out port? 0.74 cubic ft. is toothe small? Is this the due to the threelimitations subs sharing; a common chamber? The recommended sealed box volume is 0.15-0.50 cubic ft. Thanks
     
    dsjacr, Feb 7, 2012
    #5
  6. Ranger SVO

    Ranger SVO Full Member

    I should have looked up that woofer, thats the pioneer shallow mount. You WILL be fine using Pioneers recommendation. Those woofers sound really good. I have installed the Pioneer Shallow Mount 10 in a friends car, built a box using the maximum recommended box size and the performance was awesome.
     
    Ranger SVO, Feb 7, 2012
    #6
  7. dsjacr

    dsjacr Member

    So at. 74 cubic ft. shared by all three subs; what would be the best size port for this box? Thanks
     
    dsjacr, Feb 7, 2012
    #7
  8. Ranger SVO

    Ranger SVO Full Member

    I'm looking at Pioneers recommended box size, and for three in the same airspace, you will need 1.2 to 1.5 cu ft. Also, Pioneers recommended tuning for that woofer is much higher than 36 Hz. In fact its closer to 50 Hz.

    For one woofer you need a 2.5-inch port, so for three you'll need at least a single four inch port.

    I would stay sealed until your ready to build a new box.
     
    Ranger SVO, Feb 7, 2012
    #8