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Discussion in 'Audio' started by 87chvy4x4, Sep 23, 2000.

  1. 87chvy4x4

    87chvy4x4 Registered Member

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    this guy told me he would sell me his system it consist of: 400 watt majestic amp, 2 12" ultimates in truck boxes , how much is it worth he at first said 125 then he said he might have to have more, yes i know the ultimates arent that good i just want those new boxes and the amp


    CaLeB
    RiVeR cItY oFfRoAd
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  2. DBLAZER

    DBLAZER 1/2 ton status

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    If you get me a model number for the amp, I can find out its true value. As for the boxes, if they are just truck boxes you should be able to buy them new for about 75 bucks. You will want to make sur that the airspace in them will work on other woofers. A lot of the time people buy truck boxes , espacially ones for 12's, that are way to small and wont lett the woofer perform. Just remember, an average a 12" sub wants 1 to 1.2 cubic feet of air inside the box. Hope this helps. HAVE A NICE DAY.

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  3. 87chvy4x4

    87chvy4x4 Registered Member

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  4. DBLAZER

    DBLAZER 1/2 ton status

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    Length X Width X Highth But you want the internal, so you will want to take off for the thickness of the wood. For example, a box that is built w/ 1/2" wood, measures 12x12x12 outside. Internal dimensions would be 11X11X11.
    Once you have that number figured out, you will divide that number by 1728, that will give you the answer in cubic inches.
    ok here you go, it made easy.
    A square box that has the internall dimensions 13"x15"x20".
    13x15x20=3900cubic inches
    3900divided by1728=2.25 cubic feet.
    For an angle box you basically do the same thing. The only differnce is you have to find the averag width. So here is what I do. The length, and th highth are the same. But the depth is 12" on top and 20" on the bottom. So what you do is add 12 and 20 and then dived by 2 and that will give you your width. THEN you take off for the thickness of the wood and use the formula above. I hope this helps. I know that I am not the greatest teacher on paper, so if this to confusing give me the dimensions and I will figure it for you. HAVE A NICE DAY

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  5. 78k5

    78k5 1/2 ton status

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    Ok I know this can get difficult but I need to build a box for 4 rockford 12's and I have the plans for rockford for a square box, but I need to make the box look like an L can you do this by say cutting four inches in and adding four inches elsewhere or does it have to be a straight up square?
     
  6. DBLAZER

    DBLAZER 1/2 ton status

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  7. 80Jimmy

    80Jimmy Registered Member

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    So if I needed four feet of cubic airspace, would 22" long x 25" wide x 25" high be about right.
     
  8. DBLAZER

    DBLAZER 1/2 ton status

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    <font color=purple>OK, 22X25X25=13750 CUBIC INCHES OR 7.9 CUBIC FEET
    <font color=red> THAT IS OUTSIDE DIMENSIONS??? lETS SAY THE BOX IS BUILT OUT OF :
    HALF INCH WOOD= 7 CUBIC FEET
    <font color=blue>3/4 INCH WOOD=6.55 CUBIC FEET
    way to big

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  9. istallion88k5

    istallion88k5 1/2 ton status

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    Actually that's not too big, RF recommends 2 cubic feet for each 12" sub. Cause I have been trying for days to get the look I want in a new box but still get the optimal enclosure size.

    If it aint a Chevy don't raise it up!
     
  10. DBLAZER

    DBLAZER 1/2 ton status

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    Not true at all. When you say "RF" says, for which subs , the punch, the xlc, dvc, hx2, he2 , power???? None of the above work in a 2 cubic foot box. Rockford recomends 1.25 per in a seald encloser, I cant remember off the top of my head for a vented but I am pretty sure that it isnt that big, But I will vheck at my shop in the mornig and tell you. So yes, that box is to big!!!!

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  11. istallion88k5

    istallion88k5 1/2 ton status

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    On RF's page all the 12" speakers show 2.0 cubic feet for the ported version, I thought it was odd that it says that for every 12" sub, the punch hx2 etc. But that is what their page said.

    If it aint a Chevy don't raise it up!
     
  12. 80Jimmy

    80Jimmy Registered Member

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    If I needed two feet of cubic airspace what size of square box would I use with 3/4" wood included in the size?
     
  13. DBLAZER

    DBLAZER 1/2 ton status

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    Tell me the MAX dimensions that you have to work with. Let me know the aproximate width and length you want. I will help

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  14. 80Jimmy

    80Jimmy Registered Member

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    I can go 25" high, 44" long, and 25" wide w/o the wood included
     
  15. DBLAZER

    DBLAZER 1/2 ton status

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    OK. If you want to build an encloser that has two cubic feet of air space per woofer than, and I am assuming you want it for two woofers, than you can build it 15x15x40, that will give you 4.06 cubic feet internal. If it were me building that encloser then I would put a center divider in it and put two or three, 3 or 4 inch holes in it with a hole saw. WHY? Well this will let the woofers share the airspace. By doing this the woofers work together, they "couple" they will hit harder because they are working together. There are people who say this isnt true, but if you talk to anyone who , lets say COMPETES, or builds competition SPL vehicles, they will tell you that they let the wooferes share airspace.
    If you are building this encloser for one woofer then you can use these dimensions,15x15x20.5. This will give you 2 cubic feet internal.
    Now, if you are building this encloser according to the specs quoted above"2 cubic feet vented" I personally wouldnt. I woould build the encolser 1.25 per in a sealed box. And here is why.
    A) A vented encloser is designed by nature to be tuned to a certain frequancy, and at that frequncy it hits the hardest, at frequencies above and below it drops off. A sealed encloser by nature works better across the board, or it has what is called a " flat response.
    B) Size, a vented encloser is usually bigger then a sealed one, so there is more room for other stuff.
    This is how I do my encolsers, sealed. I do 99% of the enclosers that I build for the shop for paying customers. sealed.
    Now, a lot of competitors use ported enclosers, however they are usuallly tuning their enclosers to move the meter. Meaning hit really hard at a certain freq. but not the rest. I hope this helps . let me know otherwise. HAVE A NICE DAY!!!!
    oh yah, if the encloser you are building IS for two woofers and IS going to be vented then DO NOT port the divider in between the woffers. This will change the tuning of the box. The only way you would want the woofers to share is if it a sealed box.

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