Firing the Subs

Discussion in 'Car and Home Audio' started by ForistellFord, Nov 5, 2013.

  1. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    I'm going to make the sub box out of drywall; it's much easier to handle and shape. I'll use extra joint compound to reinforce it.

    So how about the head unit? Is it fine for what I plan to use it for or is it a pathetic weakling?
     
  2. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Drywall? You're joking I guess.
     
  3. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    It wouldn't be drywall, right.
     
  4. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Last edited by a moderator: Nov 7, 2013
  5. ribald1

    ribald1 Banned PLATINUM MEMBER

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    The ported VS sealed debate will rage on forever.
    In my opinion, if you don't have enough space for the proper sized box porting is a viable option. If you have the space sealed is better.

    Looks like a decent box.
     
  6. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Hate to keep running down the path of random opinion, but how about one 12 vs dual 10's? Or just one 10? Not looking to bust windows but it is a big van and I want to notice it...
     
  7. Rancherous

    Rancherous Administrator Staff Member

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    A good quality 12 in a ported box with good power would do well in there.

    Yes I told you their boxes are good and you can't build one for their prices.
     
  8. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Ah, ported, non-ported, what gives? Why do you vote for ported?
     
  9. Rancherous

    Rancherous Administrator Staff Member

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    You get more bass output from a ported box and use less equipment, 1 sub instead of 2. In order to get the same bass output from a sealed box you need to drive it with more power to get similar results. A ported box moves air out, a sealed box keeps air confined. A sealed box will be a bit crisper bass but a ported box will be a bit boomier. I have had good results with both, if you look at a home subwoofer most are ported as well. I vote ported because you are using it in a big open space the back of a van.
     
  10. aquartlow

    aquartlow In Maximum Overdrive

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    To properly choose between a sealed or ported enclosure really depends on the chosen driver's Thiele/Small parameters. The T/S parameters include but not limited to FS-Free air resonant frequency of the speaker, QTS- Overall "Q" of the driver, both mechanical and electrical, VAS-The volume of air that has the same compliance(springiness) as the drivers suspension. Usually to find a suitable enclosure you need to look at the EBP(efficiency bandwidth product) of the driver, take the parameters FS and divide by QES(electrical "Q" of the driver), this will give EBP. Generally an EBP of 100 or more suggests a ported enclosure, an EBP of 50 or lower are better suited for a sealed enclosure.
     
  11. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Some of us have a name different name for 'boomier', we call it 'muddy'.
    The human ear hears mostly the pressure side of the sound wave at low frequencies, that is why directionality is lost. In a sealed box the power of the cone receding is stored as static pressure in the box and added to the forward motion. This reduces surface distortion on the cone as it moves forward. The result is a more accurate reproduction of the original sound perceived by the ear.
    Also, a large component of how a low frequency sound is heard is 'bone hearing'. Bone hearing is why sub audible frequencies need to be created in a sound system capable of a reasonable reproduction of the original sound. Bone hearing operates on the pressure side of the sound wave only.
    The best ported system only 'works' at one frequency.
    In my opinion, if you want 'boomier', mount the speaker backward facing a shallow space with insulation in it like the locals around here do. You won't be able to tell which string the bass player hit, but you sure as hell will hear it.:D
    That's just my 2 cents. Between doing sound for rock bands and shooting a lot without hearing protection in my youth, I don't hear much anymore, but I do remember what it was like.
     
  12. burninbush

    burninbush In Maximum Overdrive

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    Go to wikipedia and lookup their article on "bass reflex" -- talks about benefits and costs.

    There is lots of info on the web re speaker (enclosure) design. It's a very complex problem.

    The thing about building the box yourself, you can easily try it with a port and if you don't like the result, glue in a plug and you're back to simple closed box.
     
  13. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    So what I've seen in my cursory search is that ported boxes make for that long, low, car rattling rap style bass, where the enclosed box gives crisper sharper tones. If it's as simple as that, I will go for enclosed because I would rather have a clean pop than a rowrr type splat.
     
  14. aquartlow

    aquartlow In Maximum Overdrive

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    Burninbush,
    I somewhat agree with this but a properly sized ported box is almost guaranteed to be quite a bit larger than a properly sized sealed box using the same subwoofer for enclosure calculations, which if you just simply install a "plug" where the port previously was a too large of sealed enclosure is what you are most likely are going to have resulting in a much less desirable enclosure. Not trying to be too technical, but a sealed box to be properly sized, will have a certain value of "QTC". QTC refers to the sound output quality/response of the subwoofer & enclosure together. A QTC of .707 is generally accepted as a box that has a flat response that allows the subwoofer to have deep extension without a "muddy" or "boomy" sound and a smoother roll-off. A QTC of .85 to 1.2 will have a more "peaky" bass but will have a sharper roll-off, this value is what "boomers" are looking for out of a sealed enclosure. Here is a page that may help with your decision:
    http://www.bcae1.com/spboxad2.htm

    ForistellFord,
    Don't forget about cabin gain/transfer function, enclosure placement and resonant frequency of the vehicle, it will have a definite impact on the output and quality of sound from whatever enclosure you choose.
    I hope this helps and good luck with your build, nothing quite like having some serious low end bass in your ride :D. Todd
     
  15. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Well, since I currently have zero low end bass, I figure I can do well with a pre-fab box (price is tough to beat) without going into too much scientific research. As of now, I'm leaning toward a single 12 in the rear of the van. I may fab a box that fits under the rear bench to hide it completely, but I don't know if I'm quite that ambitious. The prefab box I'm looking at it $33 and change shipped, so that is tough to argue against. Thanks for the replies...
     
  16. Rancherous

    Rancherous Administrator Staff Member

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    A well built well tuned ported box can sound almost as good and accurate as a sealed one. When you look at the boxes just check the subs recommendation for airspace needed and match your box accordingly. Most if not all subs will have these specs online. So buy the subs and match it to a box, you will find lots do different boxes for a 12, 1/2 cu ft, 1 cu ft etc.
     
  17. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Then why pay more for a ported box?
     
  18. aquartlow

    aquartlow In Maximum Overdrive

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    The ported box, if properly sized/tuned, will have 3db or so more output at it's tuning frequency using the same amount of power compared to the db output of the sealed box, though you will lose some of the ultra low deep bass extension. In simple terms, it's generally regarded that a 3db gain is comparable to doubling the wattage of the input power or adding another woofer with the same input power and volume per woofer ='s 3db gain , so you'll definiely hear/feel the difference. The ported box is more complex to design and build(port itself is an added cost), thus a bit more money. Once again, good luck with your install.
     
  19. burninbush

    burninbush In Maximum Overdrive

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    I'll just add a note here -- I suspect that most people don't really know what a pure low frequency tone sounds like. In the real world 'lows' are almost always a complex sound with lots of higher harmonics included.

    http://wykeradio.org/service/dvd/Testgear/Sweepgen/

    (download SweepGen.exe -- doesn't need to be installed, makes no changes to your puter, just click on the file to run it)

    This little app will turn your pc's soundcard into a very fine audio oscillator -- and has many useful additional features. Play it on your puter, or run an extension cable from your pc's speaker output to a line input on your receiver [or other device that has speakers] and see what a low-distortion bass tones really sounds like.
     
  20. Rancherous

    Rancherous Administrator Staff Member

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    Just listen to some pipe organ music :D
     

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