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2 sub enclosures with slight diferences in interior volume.is this bad?

Discussion in 'Audio' started by 3car, Jul 10, 2003.

  1. 3car

    3car 1/2 ton status

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    i built two sub enclosures that go in the back corners of my blazer.on the passenger side,i notched the box around the fuel filler panel and fiberglassed around it to minimumize space loss.this results in a diference of volume of about 14% between the boxes.the volume is still within the manufacturers specs for the kenwood excelon subs i plan to use,but i was wondering if this diference will cause an unpleasant sound.i could possibly use poly fill in the smaller of the two boxes to compensate for the reduced volume.tell me what ya'think.i called kenwood tech support,and they said,duh.....i dont know. /forums/images/graemlins/confused.gif
     
  2. AntAZBlaz

    AntAZBlaz 1/2 ton status

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    The most important part is that there is no sound cancelation between the two speakers. If the are the same speakers same power that size difference should not really matter. you should definitly stuff both of those boxes though not just one to compensate. the blazer is not exactly a perfect sound stage so i wouldnt worry about it unless your trying to get ready for some competitions.
    king
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Well, if the boxes are within spec (what IS the spec by the way?) you shouldn't need to use polyfill at all.....

    My take is this:

    If these are sealed boxes, then adding extra interior volume generally allows the speaker to play LOWER since there is less mechanical damping (air resistance) in the box. A smaller box tends to create more resistance, and the speaker can't move as easily, or play the lower notes as effortlessly.

    If your boxes are two different volumes, one will play deeper than the other....instead of playing the polyfill game, why not just reduce the volume of the larger box by building some sort of baffle internally to steal space away from the speaker???? Ultimately, you can still polyfill the boxes.....but at least you'll be working with equivalent volumes from the start....

    BTW -> Don't make any decisions about sound quality until you've gotten the speakers FULLY broken-in. That can take up to 40 hours.....depending on how good your system and ears are, you will HEAR them getting more relaxed and playing deeper as they break-in. It IS something I could totally notice on my own subs.

    Anyway, if after the break-in you want more low-end, you can start stuffing the polyfill in there. There is a practical limit, so if you built the box TOO small for the response you want.....no amount of poly will make it sound BIG! /forums/images/graemlins/grin.gif
     
  4. 3car

    3car 1/2 ton status

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    the subs are kenwood eXcelon kfc-xw10db,and factory specs call for 0.6-1.25 cu ft per sub.im not sure if that is including the sub itself or not.i have .86 in one and .73 in the other,not including space taken up by the sub.
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    the subs are kenwood eXcelon kfc-xw10db,and factory specs call for 0.6-1.25 cu ft per sub.im not sure if that is including the sub itself or not.i have .86 in one and .73 in the other,not including space taken up by the sub.

    [/ QUOTE ]


    .73 is getting a bit on the "small side", especially considering that you haven't subtracted out the driver displacement......which is something that you are supposed to do when calculating box volumes. (You are also supposed to subtract port volume on ported boxes, material thickness of cabinet, and any bracing inside the box)

    If I had to guess, I'd say with the driver displacement factored in you are at the very bottom of the recommended spec from Kenwood. What that means is that the speaker will sound "tight and snappy" but will not reach as LOW as a box that was closer to the 1.25 cu ft size.
     

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