subwoofer box, divider or no divider?

Discussion in 'Subwoofer Box and Custom Fabrication' started by guitarfreak235, Dec 17, 2011.

  1. I have an enclosure behind the seat of my truck with 2 kicker cvt 12s. They are sealed and have a divider inside separating the subs.the low end bass is a bit lacking.... my question is would it be benificial to remove the divider? would this lower the harmonic frequency enough to make the low end good? the link to the subs with enclosure and the specs are below

    your help is much appreciated!
  2. Ranger SVO

    Ranger SVO Full Member

    I always did that with prefab boxes. I would drill a 4 or 6-inch hole in the divider so that the lower bass frequecies would improve. And it always worked.
  3. deepbass

    deepbass Full Member

    So would say a pvc pipe between the two work? As prefab subs have that little lip on the sides.
  4. Ranger SVO

    Ranger SVO Full Member

    I don't see why not. If they can share the airspace there will be some improvement in sound. Just make sure the PVC is atleast 4-inches or more
  5. deepbass

    deepbass Full Member

    well i was thinking, run a router round the inside of both boxes on the sides were they will join, then when i put them together i would screw and glue them together. thus making one box inside, all there would be is a 2" lip all the way round inside.

    think this would be better?
  6. darryle

    darryle Full Member

    What if each sub has an identical mono amp driving each one
  7. deepbass

    deepbass Full Member

    Still varibles. Even same model amps are not born unequal. Then you have the settings to match spot on.
  8. danny_khan

    danny_khan Full Member

    are you still facing the same problem with low end Bass or is it ok now?
  9. deepbass

    deepbass Full Member

    Depends if hes joined both chambers. If its a twin box with a divider. I would router out the middle to leave the outer part left as a mid brace. Then it would be one air space
  10. ok ill put a hole in it, but is a pvc pipe necesarry? or could i just put a hole? and would the size of the hole effect the tuning at all?
  11. deepbass

    deepbass Full Member

    Needs to be at least 4-6"
  12. Ranger SVO

    Ranger SVO Full Member

    I think we are missing something here.

    First, two speakers in the same air space should be treated as one speaker.
    The following properties apply
    a. Fs driver resonance for the two driver will be the same as that of the single driver
    b. Qts of the pair will be the same as that of the single driver
    (above are the reasons we never put two different woofers in the same enclosure and one of the reasons the box size improves low end performance)
    c. Vas (and the associate box volume) will be twice that of the single driver.
    d. Sensitivity will increase +3dB for a parallel connection and -3dB for a series connection when compared to the single woofer.
    e. Cone excursion will be half that when compared to the single driver.

    Because we treat two woofers in the same air space as one woofer, we need to use one amp. Attempting to balance two amps is not going to happen

    Now if we take two seperate boxes with two woofers these properties do not apply.

    If we take two seperate boxes and attach them so that they are one, the connection between the two must be perfect. No air leaks. If we use a PVC pipe to connect them there is NO tuning effect, the PVC pipe should have a diameter of atleast 4 to 6-inches.
  13. deepbass

    deepbass Full Member

    So what doea that all mean if im running two identicals subs. So the 11.tmm xmax is halved on both? So ill get half the excursion as then i would if they were in seprate boxes?

    So if all of what you have said means running one common chamber for both subs decreace thw performence of them together spretly. Are you saying its best to run each sub in there own air. Which then by the above would double the excursion as both subs would be acting on there own air.
    I was told to run them both in one box rather then two. Ie 3.0cuft rather then 2 x 1.5cuft boxes.

    If running them in the same both halfs there excursion. Why would it not be better to run two boxes with one amp running both? I ask because if i can make two boxes rather then one big box and have the same sound and from what your saying. Keep the speced xmax then wouldnt i be better to house each sub in its own box. But run them both from one amp. Both boxes will be identical in volume. As will the subs. So it should sound the same as one box. Or is having one box house 2 subs lower the hz i can get down to?

    Can you clear my doubt up over performence and sound over 1 or 2 seprate boxes.
  14. darryle

    darryle Full Member

    Ah Ranger I'm confused, so two soundstreams D200's bridged mono each driving an identical 10.So coupling the boxes would be a bad idea?
  15. Ranger SVO

    Ranger SVO Full Member

    Its always best to run both woofers in the same enclosure. I knew I should not have posted property e, but what it means is that the woofer doesnt have to work as hard to produce the same frequency at the same volume level. That +3dB gain means its louder and its not working as hard.

    And yes, instead of two 1.5 cu ft boxes you can run just one 3.0 cu ft box. But you can also get away with one 2.25 to 2.5 cu ft box with out a penalty. Remember that the box design equation for size is not linear. Remember your high school math, a linear equation can be written in the form y = mx + b or in the form Ax + By = C. The size equation for a sealed box cannot be written in these forms

    Box Volume Equation.jpg

    Its obvious that this is not a linear equation.

    If your gonna run seperate amps to each woofer, then its best to run each woofer in its own enclosure.
    Last edited: Dec 22, 2011
  16. deepbass

    deepbass Full Member

    Ah right. So both would still have full excursion. (11. 5mm in my case) but the sub would find it easier to produce that much excursion. Which i guess is why you get lower bass. As the subs dont have to work so hard to produce lower bass.
  17. i think he means 1 sub in a 3 cubic ft enclosure will have double the excursion of that of 2 subs in the same enclosure... not 2 subs in a 3ft enclosure vs 2 separate subs in 2 boxes with 1.5ft of volume. but i could be wrong haha but the rest makes sense to me.

    but also... was deepbass thinkin that they were in 2 separate boxes? not 1 box with a divider? cuz of the whole pvc pipe, lip on the box deal
    Last edited: Dec 24, 2011
  18. Ranger SVO

    Ranger SVO Full Member

    I'm not sure I would have explained it that way, but it works so OK
  19. deepbass

    deepbass Full Member

    ok, just to put this in to the mix
  20. last question!!!!

    would multiple small diameter holes i.e. 1 or 2 inches work, given there are enough to have the same area?