/ Register

Need help with new box and port calc.

Discussion in 'Subwoofer Box and Custom Fabrication' started by 2k Z71, Jun 7, 2009.

  1. 2k Z71

    2k Z71 Full Member

    Okay guys i've decided i'm going to build another new box for my truck (2000 Silverado). This time i'm going to be doing some fiberglass work on the truck but basically that will start and end with the face. I want this box to be ported to about 35hz (or close to).

    This is a wedge style box.

    Length-57
    Front Height-10.75
    Back Height- 6.75
    Width-16

    If anyone has done a box under the back of the silverado you know you have the driveline to accomidate for.

    Hopefully this picture will help out....
    [​IMG]

    I'm wanting to do the port just above the driveline the driveline is roughly 6.5" tall and 17.25" wide.

    I'm looking to use a square/slot port if possible. Remember that the front will be fiberglassed so if need be i can move the port forward (toward the face of the box) a few more inches...

    Let me know if you need any more information.

    Also 2 Diamond Audio 12" subwoofers powered by 2 Diamond Audio 600.1 amps
     
    2k Z71, Jun 7, 2009
    #1
  2. 2k Z71

    2k Z71 Full Member

    also, the port does NOT have to be above the driveline
     
    2k Z71, Jun 7, 2009
    #2
  3. Ranger SVO

    Ranger SVO Full Member

    I'm guessing how much room that hump is taking up. I'm estimating that you usable volume is only around 2.6 to 2.7 cu ft. For two 12-inch woofers this is not good. For a ported box this is not good.

    Lets see what we can do. A 12-inch woofer needs a 4-inch round port, two 12-inch woofers need two 4-inch round ports or a single 6-inch round. The problem is that a port this size is too long for your box.

    The biggest port (with a reasonable length) would have a cross sectional area around 20 sq inches. So make the port 2-inches by 10-inches. The length should be 13-inches long. Port velocity will be a little high, but its the best we can do with what we have.
     
    Ranger SVO, Jun 7, 2009
    #3
  4. 2k Z71

    2k Z71 Full Member

    Well i know when it was all wood it was 2.57cu ft. Obviously i will get a little more with the fiberglass, maybe 2.75cu ft tops.

    Would moving the port away from the driveline hump help at all? That way being able to get a port slightly larger than 2" tall? I've been told that it would be better to have the port and woofers on the same face. Is that true? If that's not true i could possibly move the port to the side of the box?

    This is the first box i've ever ported. Normally i build boxes with minimal space so sealed is usually the only way to go, but i'd like something different for my own personal vehicle




    I could possibly raise up the seat a few inches to get a little more space under there i suppose...i've seen it done a few times but never really looked into it....
     
    2k Z71, Jun 7, 2009
    #4
  5. Ranger SVO

    Ranger SVO Full Member

    In a perfect world the port would be on the same face as the woofer. But I don't see it happening on your box. So second best, put the port where the sound can reflect off something. Example put the port on one of the two sides. You'll be suprised how well it will perform that way. Where ever you put it, make sure its opening is unobstructed by atleast 3 or 4 inches.
     
    Ranger SVO, Jun 7, 2009
    #5
  6. 2k Z71

    2k Z71 Full Member

    Yeahhhh if i were to put it on one of the two sides there's only about 1" between the box and the door so i don't think that would work....

    I did however figure out if i raise the backseat a measly 2.5" i would be able to get the box to 3.77 cu ft. + the fiberglass area should get it to right around 4 cu ft. No one really sits in the backseat for longer than a quick run to the store (i don't want to get rid of the backseat because i do put groceries and what not back there) and even with me sitting in the backseat (6ft tall) i would still have room with 2.5 less inches above me.

    What do you think about doing that? So it would still sound good with the port and i'd still be able to fit people back there...
     
    Last edited: Jun 7, 2009
    2k Z71, Jun 7, 2009
    #6
  7. Ranger SVO

    Ranger SVO Full Member

    I've never tried to raise the seat in a GM. But if its possible, then yes it will work.
     
    Ranger SVO, Jun 8, 2009
    #7
  8. 2k Z71

    2k Z71 Full Member

    Yeah, took a look at the seat and spoke with my old boss (owner of car stereo shop locally) and he said he's done it before without any problems. I just need to figure out pricing for the metal needed for it.

    I checked out a port calculator website online and it said at 4cu ft tuned to 38 hz
    height-2.5"
    width-16"
    length-5.44"

    does that sound correct? or do you have any other recomendations on the port length?
     
    2k Z71, Jun 8, 2009
    #8