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Need some kelp with Box Size.

Discussion in 'Audio' started by Bowtied, Jul 22, 2001.

  1. Bowtied

    Bowtied Registered Member

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    Hey folks, How's it going?
    My question is how big should I build my box for a 12 inch Cerwin-Vega sub? It's currently in a 2 sq. foot box with a 4 inch port and it sounds incredible. The reason I'm screwing with a good thing is because I need the extra space in the back. That's why I'm thinking about going with a 1 sq. foot box sealed with no port.
    ANY info/experiences is appreciated! (ie. how would the sound change, if any?)

    Andy (Bowtied)
     
  2. Prembird

    Prembird 1/2 ton status

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    Look at the paper work that came with the sub.. if you dnot have it look it up on the web.. it will give you the recommended sealed enclosure... stay as close to that number as you can...

    Prembird
    [​IMG] <font color=blue> If it aint</font color=blue><font color=red> LOUD </font color=red><font color=blue> Then turn it </font color=blue><font color=red> UP</font color=red> [​IMG]
     
  3. Bowtied

    Bowtied Registered Member

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    I am right there with ya, only when I checked the web site it did'nt say anything about a sealed enclosure. Another problem is that the sub is at least 4 years old so I have no literature on it and when I go to the web site it has only the info for the new subs. I did notice that for thier new subs they recommend mostly ported enclosures, I can't remember any of thier specs for the new subs that said anything about a sealled box. From what I've seen, I think most popular brands of 12's say 1 cubic foot if sealled, do you think I should give it a shot?
     
  4. Prembird

    Prembird 1/2 ton status

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    a good rule of thumb on 12's is... 1.25 to 1.5 per sub... you can get away with a 1 cube setup but you wont get the most out of the subs.... I have a couple of programs that allow me to put the specs. in and compair them in different boxes and what not.. this way i can see the spl and curves on all of them and figure what will be the best way to go... what is the best type of box for the size i am trying to keep to... What is the model number on your 12's... i will see if i can dig up some specs on them...

    Prembird
    [​IMG] <font color=blue> If it aint</font color=blue><font color=red> LOUD </font color=red><font color=blue> Then turn it </font color=blue><font color=red> UP</font color=red> [​IMG]
     
  5. Greg72

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

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    Bowtied,

    I am assuming you mean that the box is 2 cubic feet total volume. Something like 24"x12"x12".

    My own experience is that a ported box that is setup properly will be 3dB louder than a box that is sealed of similar volume. That is important because a single speaker that plays +3dB louder, is the same as TWO speakers playing in a sealed enclosure!!!

    Let me make sure that is clear: 1 properly set up 12" sub in a ported box will sound just as loud as TWO 12" subs in a sealed box!!!

    Unfortunately, if you reduce the box size AND remove the port, you will be penalizing yourself twice. Removing the port will make the speaker a LOT less capable of the producing LOW bass and high volume, and as you reduce the space in the box in a "sealed design" it tends to create more mechanical resistance for the speaker to overcome (less air, means there is more resistance to motion of the speaker cone) so the speaker will have a harder time playing loud and low....

    If you want the interior space back....it's going to "cost" you, in the way that sub sounds. Hopefully Prem can find some specs to give you that will help you make the best enclosure possible even though it will be smaller.....

    Good luck,

    -Greg72
     
  6. Prembird

    Prembird 1/2 ton status

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    The sub in a ported enclosure will sound more boomie.... but will be more accurate in a seal enclosure... atleast that is what i was taught and i have always heard... that is the trade off... it will sound like less output from the sub but will be more accurate on reproducing the bass note...

    Prembird
    [​IMG] <font color=blue> If it aint</font color=blue><font color=red> LOUD </font color=red><font color=blue> Then turn it </font color=blue><font color=red> UP</font color=red> [​IMG]
     
  7. Greg72

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

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    I think the stereotype (no pun intended! [​IMG]) that ported boxes are "boomy" comes from using boxes that are too small. If you study the response curves that are now posted on the "box builder" section of the JL Audio Website you can see what happens pretty clearly. If you choose a "Normal" or "Purist" design the box is a LOT bigger than if you choose a "dB Monster" (aka BOOM BOX)

    As the speaker box gets smaller, the speaker gets more efficient and louder....BUT over a narrower range of frequencies. Usually, you will find that the frequency range of 60Hz to 80Hz is becoming exaggerated. To some people, that is what they consider BASS. That one booming note that we've all heard coming down the street from 3 blocks away... If you like that, it will be easy to build a box....keep it small and port it. Or build a bandpass enclosure.....even more efficient, over an even narrower frequency range...!

    Trying to get a super-flat and accurate frequency response in a noisy K5 is (in my opinion) probably a waste of effort. It might make more sense to accept the fact that the K5 is a "hostile audio environment" and build a stereo that is punchy &amp; loud enough to be enjoyed there. [​IMG]

    I've decided to go with ported enclosures for my K5....if I ever get them finished, I will be able to spend some time listening to them and determine if my strategy was correct or not...

    -Greg72
     
  8. Bowtied

    Bowtied Registered Member

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    Prembird and Greg72, thanx for the info.
    Prem, I will try to get the sub out soon to take a look at the back of it to see if there is any numbers on there that you'd be able to use.

    At this point, you guys have given me some good info to work with but let me bug you with one more question. I've accepted the fact that if I reduce the size of the box it will reduce the volume and freq band of the sub, but will it (with sufficient power of course) still thump good in a one cubic foot sealled box? I listen to mostly country and occasionally some rock so I'm not after something that'll set off car alarms 3 blocks away or anything. I have a 160w Sherwood driving it now in the 2 cubic foot ported box now and I am totally amayzed with how hard it hits, especially for just one speaker! Again, I'd like to keep it the way it is now but I need the luggage space since we use the blazer for most of our road trips.
    Anyhow, one last thing,
    What if........I went a one cubic foot box WITH a port?
    Let me know what you think,
    Thanks!!!

    Andy
     
  9. Greg72

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

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    I don't know if you've got just a simple box sitting behind the rear seats now....I am guessing that's the setup.

    Have you considered trying to build something into the side panels? I know that at least one other person with a late-model K5 did that....and it saves quite a bit of cargo space. I think this is the URL:

    http://community.webshots.com/user/gblanchette72

    I'd hate to see you throw away good sound just to get some cargo space....if you know that 2 cu ft sounds good with a port, I'd be trying to figure out ways to get the same box volume and port into a different configuration.

    If I had to guess about the performance of a 1 cuft box WITH a port added, I'd say the sound would not be as deep as what you have now....you might get similar volume out of it, but only at the upper frequencies (~80Hz).....more boomy, and one-note'ish I would guess.

    It's a lot of work to build a solid box....personally, if you are going to spend the time to do it again....you'd be safer trying to build a box that you already KNOW you like the sound of.

    Just my $.02 [​IMG]

    -Greg72
     
  10. Prembird

    Prembird 1/2 ton status

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    Personally i think 1 cubed is way to small to port.. but that is me.. As for it if will sound good.. i would say yes on one cubed foot it should be fine considering the type of music you are listening to.. But as Greg72 pointed out.. look into building another enclosure.. into the sides or something.. this way you can keep a good sound and free up more space... But if you wanted to go with a one cubed setup and was worried you would lose all low end... you should be just fine... Since most of the bass notes you will be playing wont be a boommmy type of note.. you should be fine...look into what greg72 said though..

    Prembird
    [​IMG] <font color=blue> If it aint</font color=blue><font color=red> LOUD </font color=red><font color=blue> Then turn it </font color=blue><font color=red> UP</font color=red> [​IMG]
     
  11. Bowtied

    Bowtied Registered Member

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    Greg72 and Prembird,
    Thanks again for the info. I think I figured out what to do. I think I'll just go ahead and build a 1 cubed sealed and try it out. From the way you guys describe it, it sounds like there's ups and downs to both (volume vs accuracy; etc...) so I guess I won't really know until I try.
    Thanks Again for all your help! I'll be sure to let you know how it sounds when I get it done.

    Prembird: I'm hoping to pull the speaker this week. If I do I'll be sure to jot down any numbers I find on the back and maybe that would help us some.

    Greg72, Very innovative enclosures!!! You could make money on those dudes (The wood version of course) :)

    Andy (Bowtied)
     

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