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  1. #1
    dts geek swwdts's Avatar
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    Question Cubic Feet for subwoofer boxes......

    Ok,when I go to buy a sealed Q-LOGIC box & a sub.(sold sep).The box & the subwoofers have a cubic feet needed message.How can they measure (in feet) the cubic air space?The reason I need to know about cubic feet is,for my home I want to use a car subwoofer & box.

  2. #2
    Forum Regular N. Abstentia's Avatar
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    Why would you want to use a car subwoofer in your house? Is your room only 4'x8' or something?

  3. #3
    Loving This kexodusc's Avatar
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    Measure the width, height, and depth of the box in inches, subtract 2 X the thickness of the walls from each dimension, and then divide that total by 1728. That's cubic feet of the box.

    But yeah, sealed car subs probably aren't a good idea for your home unless your room is 10 X 10 or smaller...and even then it might be pushing it.

  4. #4
    dts geek swwdts's Avatar
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    Thanks for the info.! My Keenwood HT came w/ an 8" sub ( no amp / non powered ) & I want to go up to a 10" without spending over $ 350

  5. #5
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    A ported car sub will provide a lot more bass than home sub in it's pricerange. For the most part car subs are of better quality than home subs. In the pricerange he's looking at he'd be lucky to pick up a sub with a driver worth more than $50 in it.

  6. #6
    Loving This kexodusc's Avatar
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    Quote Originally Posted by calegrant
    A ported car sub will provide a lot more bass than home sub in it's pricerange. For the most part car subs are of better quality than home subs. In the pricerange he's looking at he'd be lucky to pick up a sub with a driver worth more than $50 in it.
    This is absolutely false...Not only are car subs generally terribly inefficient compared to home audio subs, thereby requiring alot more power just to play as loud as home subs, but they also generally have much higher frequencies of resonance, making them all but impractical outside a car's cabin. I won't even get into the ridiculous xmax on car subs.

    You do get the odd woofer with T/S parameters suitable for both applications, but then you're compromising, not getting the best for either.

    Car subwoofer drivers suffer from the same level of ridiculous markup as home subwoofers. I have a crappy MTX 10" woofer and an Infinity woofer that both sold for over $140, a $39 Dayton woofer, designed for both car and home application ironically enough, replaced them in both my vehicles...lower Fs, higher sensitivity and better sound quality....with bucking magnet to boot!!!

  7. #7
    Forum Regular N. Abstentia's Avatar
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    Quote Originally Posted by calegrant
    A ported car sub will provide a lot more bass than home sub in it's pricerange. For the most part car subs are of better quality than home subs. In the pricerange he's looking at he'd be lucky to pick up a sub with a driver worth more than $50 in it.
    Please tell me you're not serious. How could anybody in their right mind say something like this?

  8. #8
    dts geek swwdts's Avatar
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    Question

    Quote Originally Posted by kexodusc
    Measure the width, height, and depth of the box in inches, subtract 2 X the thickness of the walls from each dimension, and then divide that total by 1728. That's cubic feet of the box.

    But yeah, sealed car subs probably aren't a good idea for your home unless your room is 10 X 10 or smaller...and even then it might be pushing it.
    If I have done this right ? I keep coming up w/ 67.7 BUT the inside box messurements are ROUGHLY 9.5x.9.5 which =19 but, when I / 1728/19 I get 90.4.There is no way it has 90.4 cubic air space???????

  9. #9
    Loving This kexodusc's Avatar
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    Slow down, dude

    Quote Originally Posted by swwdts
    If I have done this right ? I keep coming up w/ 67.7 BUT the inside box messurements are ROUGHLY 9.5x.9.5 which =19 but, when I / 1728/19 I get 90.4.There is no way it has 90.4 cubic air space???????
    There's so much wrong with what you just typed....

    I assure you 9.5 X 9.5 does not equal 19. You are adding, not multiplying...how big a box are you trying to make?

    I'm sorry, I took for granted that you would know to mulitply the internal dimensions to get volume...length x width x height.

    For example, if your inside measurements are 9.5 x 9.5 x 9.5, your cubic volume is 0.496 cubic feet.

  10. #10
    dts geek swwdts's Avatar
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    Hmm? I remeasured it & it is 11.5 x 11.5 x 11.5. = 1520.875 / 1728 = 0.8801359 Would I hunt for a box w/ 1 cubic foot air space?

  11. #11
    Loving This kexodusc's Avatar
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    Nah, you can use that box, just use a fair amount of damping material and you'll be close...

  12. #12
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    haha I like the "slow down" dude.
    You can get good car subs who do have good xmax. Take a Rockford Fosgate power series sub. They are such monsters! Then again they are designed for high SPL outputs.
    I won't even mention the Pioneer TS-W3002's...

  13. #13
    Loving This kexodusc's Avatar
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    Quote Originally Posted by audio amateur
    haha I like the "slow down" dude.
    You can get good car subs who do have good xmax. Take a Rockford Fosgate power series sub. They are such monsters! Then again they are designed for high SPL outputs.
    I won't even mention the Pioneer TS-W3002's...
    High xmax is great for getting loud volumes and a bit lower bass for not much money, but unfortunately it's destructive to sound quality. Transient response suffers, distortion increases. All things equal, smaller xmax drivers sound better. In a car, where you're fighting the traffic noise and cars own noises, more volume for cheap is good, in a home, not so much.

  14. #14
    dts geek swwdts's Avatar
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    In the mid 90's I had my lowrider w/ nothing but RF.& a h of alot of of dynomat.I was into SQL comp.I never won but,I had fun.As far as RF for the home my Kenwood amp is only 100 x 6 & as of Kex & I where hunting for a replacement sub for my home the RF rms was way to high for my amp.Thanks anyway audio am....for your info.

  15. #15
    Suspended superpanavision70mm's Avatar
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    Those KEENWOODS are awesome! When I play my gangsta rap I love my room to sound like a rumbling truck....brrrrrr brrrrrrrr brrrrrrr ump.

  16. #16
    dts geek swwdts's Avatar
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    Thats how I blew it up.I had it set on - 12db while playing let me ride & it went pow & the spider has a hole in it now making it sound like s. So, I am buying a new subwooferfor my HT.

  17. #17
    Forum Regular audio amateur's Avatar
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    Quote Originally Posted by swwdts
    In the mid 90's I had my lowrider w/ nothing but RF.& a h of alot of of dynomat.I was into SQL comp.I never won but,I had fun.As far as RF for the home my Kenwood amp is only 100 x 6 & as of Kex & I where hunting for a replacement sub for my home the RF rms was way to high for my amp.Thanks anyway audio am....for your info.
    hmmmm, what exactly do you call "SQL" ? I am intrigued. It's hard to believe you've done "competition" and don't know how to calculate the volume of one's box. -don't take me badly here.

  18. #18
    dts geek swwdts's Avatar
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    As far as Comp.Yes I was.I was a member w/ the MECA car audio & SQL is a comp test just like SPL.Anyone w/ a $5 system can have spl as far as air.vol. I used Q-Logic boxes.I did not have to know cubic air vol.A normal person could enter even w/ a factory system.I did comp. in the SQL series of the comp.SQL = SOUND QUALITYT LEAGUE anyone can do spl Most of the cars in any redneck town go thump like they have a trash can in the trunk.To where w/ SQL it dep.on how loud the whole song is w/ out getting distored. MECA stands for Mobile Electronic Corporation of America
    Last edited by swwdts; 05-12-2006 at 05:25 PM.

  19. #19
    Forum Regular audio amateur's Avatar
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    Quote Originally Posted by kexodusc
    High xmax is great for getting loud volumes and a bit lower bass for not much money, but unfortunately it's destructive to sound quality. Transient response suffers, distortion increases. All things equal, smaller xmax drivers sound better. In a car, where you're fighting the traffic noise and cars own noises, more volume for cheap is good, in a home, not so much.
    Aren't ya contradicting yourself here a little? At first you were saying car subs had crappy xmax, and now that I say they don't, you say it has negative effects on SQ haha. Anyway, I do get the point don't worry.

    Home subs are hard to get around where I live, as well as home sub amps, that's why I bought the amp in the states, and bought a car sub.
    -I'll keep you up to date with my project (I'm about to go purchase the wood- been having trouble deciding what dimensions would sound best and look best.)

  20. #20
    Loving This kexodusc's Avatar
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    Quote Originally Posted by audio amateur
    Aren't ya contradicting yourself here a little? At first you were saying car subs had crappy xmax, and now that I say they don't, you say it has negative effects on SQ haha. Anyway, I do get the point don't worry.
    Never said car subs have crappy xmax...they generally have high xmax, which is not great for SQ...it's good for compensating for the fact their generally inefficient. Xmax is cheaper than efficiency for designers to incorporate into a driver...so they have high excursion. It's a shortcut.
    There's a point where a speaker stops behaving like a resonating device that produces music, and more like a piston in machinery that does work...high xmax is all the rage for people looking for SPL bragging rights, but it doesn't do anything for SQ.

  21. #21
    Forum Regular audio amateur's Avatar
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    Quote Originally Posted by kexodusc
    Never said car subs have crappy xmax...they generally have high xmax, which is not great for SQ...it's good for compensating for the fact their generally inefficient. Xmax is cheaper than efficiency for designers to incorporate into a driver...so they have high excursion. It's a shortcut.
    There's a point where a speaker stops behaving like a resonating device that produces music, and more like a piston in machinery that does work...high xmax is all the rage for people looking for SPL bragging rights, but it doesn't do anything for SQ.
    I mis understood the "ridiculous xmax". I though you were saying they had poor xmax in general, but obviously you meant the opposite. Anyway, I just got the wood cut to my specs, I never realised how big a 13*13*13.5 cube would be. It's quite impressive.

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