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free air sub

Discussion in 'Car Audio' started by Timmos, Apr 16, 2009.

  1. Timmos

    Timmos New Member

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    G'day all,

    I've got a mate who wants to put a sub and amp in his boot, but isn't willing to sacrafice any boot space for it.

    What are your opinions on this:
    Free-air sub

    keep in mind he's not after anything incredible, just something that makes a bit of bass. Will this work alright?

    Thanks.
     
  2. Fun_Bucket

    Fun_Bucket New Member

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    I don't get it- your mate really wants a sub, but he doesnt want to sacrifice any boot space, well then he shouldn't be after a sub then should he?? Like saying hey i wanna slam my car but i dont want it to ever scrape or bottom out!!
     
  3. Timmos

    Timmos New Member

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    There's no reason why he can't be after a sub. He just wants to know his options as far as saving the most bootspace he can.

    Did you take a look at the link? it can be done. But i wanted to know how well it would work. Using the boot as a enclosure i imagine would be rather difficult, air and sound escaping throughout the boot.
     
  4. delcowizzid

    delcowizzid on holiday

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    I used to run my pioneer 12" free air works great (apart from the rear quarters of the old HQ got soft from flexing all day).just make sure you get a sub that is able to be run free air youll be all good.
     
  5. Timmos

    Timmos New Member

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    Cheers mate,

    It was between free air or a slim line sub box. I think free air is the way to go
     
  6. Fun_Bucket

    Fun_Bucket New Member

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    If you go a free air setup, your gonna need a more powerful setup to achieve the same sort of results as if you were to use a ported/sealed setup. You'll lose both clarity and power going a free air setup. And it will most likely cost more aswell. Yes it can be done, but i don't think you'll find many car audio nuts that would reccomend it-
     
  7. Timmos

    Timmos New Member

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    Yeah i thought the same, would prob need to sound deaden the boot. but with the right gear i can see it being amazing... bigger box, bigger boom. well a boot is a pretty freakin big box
     
  8. Fun_Bucket

    Fun_Bucket New Member

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    Quote: Bigger box, bigger boom, No-It doesent always work like that, the majority of decent subs, will state the ideal build inclosure dimensions, whether it be sealed or ported ect.. That amount of free air in your boot space, will exceed those dimesnsions.
    Sound deadning won't even come into it
     
  9. holdenboy

    holdenboy Custom Car Stereo Systems

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    A bigger box can be a good thing, depending on:
    1) The power given to the sub/s
    2) The quality of the sub - a higher quality sub will usually have "stiff" suspension, and works better in a small-medium sized box. A cheaper sub will usually have a looser suspension and therefore will sound better in a bigger box.

    Generally the free air type subs have a loose suspension as they are designed to be used with "extra large" enclosures (i.e. a boot). Just make sure the boot seals are good and sometimes it pays to put a peice of MDF in between the rear seats and the boot, effectively sealing off the boot from the inside of the car.

    Free air subs arent that great, and some issues mounting the sub on the parcel shelf (assuming thats where it will be mounted): firstly you'll be attracting unwanted attention by would be thieves, and secondly if the windows arent tinted the subs will be eventually damaged by the sun.
    But as you said, he's not after anything incredible. So its definately an option.
    Another option would be a good set of 6x9s. If installed properly and given a decent amount of power (80+wrms) they will have more bass than a single 8-10" free air subwoofer, plus you get the added benefit of full range sound too ;)

    Edit: The write-up youve provided in that link - cutting the metal in between the rear seats and the boot is actually illegal....and you can be defected for it if you come across a cop who has it in for you.
     
    Last edited: Apr 16, 2009
  10. StoneX

    StoneX New Member

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    Free air subs actually have tighter suspension due to the lack of air suspension of a large/inifinite box ;)
     
  11. holdenboy

    holdenboy Custom Car Stereo Systems

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    oh yeah....sorta confused myself in that post haha

    long day ;)
     
  12. Trent1291

    Trent1291 New Member

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    I really dont rate free air subs... unless its a powerful 800 rms at least subbie... not many meet that unless its kicker... dont know many other great subs. Each sub needs a certain amount of air literage in its enclosure/ boot... so the sound quality might be pretty poor and dull... best getting a sub box for it and having it just to one side...
     
  13. trentvy

    trentvy Dodges raindrops

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    maybe try a slimline sub, youll probably get more bang outa your buck. the reviews on free air arent that great, that being said ive never heard one myself.
     
  14. Trent1291

    Trent1291 New Member

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    and to add, free air subs dont always look the best either... personal opinion
     
  15. Not_An_Abba_Fan

    Not_An_Abba_Fan Exhaust Guru

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    Why doesn't he make a panel that fills in one side of the boot and only uses the quarterpanel area? Seal the front and the body of the car will make up the rear of the enclosure.
     
  16. theSeekerr

    theSeekerr New Member

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    Take a look at the specs on the sub - there's four important numbers on there, and one less important one that's usually the biggest.

    The first one is Qts, or System Q. To cut a long story short, for free air mounting you want a Qts between 0.65 and 0.9. Lower and you'll get very little bass, higher and you'll get a one note boom with very little bass below that. Ideal is 0.7ish.

    The second is Fs, or Resonant Frequency. Essentially, in a free air setup, this is the lowest note the sub can play, without resorting to equalisation. Considering that a properly set up sub should only handle the range up to, say, 100hz, you want Fs to be fairly low. No need to get all the way down to 20hz, though, there's very little musical content down there, and you won't be able to tell over the road noise anyway. So something around, say, 30-35hz is sufficient. No higher than about 41hz (the low E string on a bass), though, or you'll lose musical content.

    Which brings us to size. Some way bigger is better, others say that big drivers sound "slow". I tend to find that big drivers have too many compromises in their design to sound terribly musical. I don't like 18", and I've never seen a car audio 15" that I liked, although there are pro-sound drivers that size that sound OK. 12", or, better, twin 12" is a good compromise. Bigger drivers tend to have lower resonant frequencies, but don't buy them just for that.

    Next, consider X-max, which is the distance the driver is designed to "throw" the cone without damaging anything. What it needs to be depends on how loud you need it to go, but basically, I wouldn't bother with anything less than 10mm.

    And finally, power handling. On a lot of cheap subs, this number is basically a lie. Back in reality, realise that, if everything else is done right, you'll get about 86dB from just 1 Watt, 96dB from 10 watts, 106dB from 100 watts, 109dB from 200 watts, and 112dB from 400 watts, 115dB from 800 watts, and 116dB from 1000 watts. Or, to put it another way, get one rated for around 200 watts RMS, and ignore the pure fiction "Peak" figures.
     
  17. TrikkBen

    TrikkBen I'm Back :D

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    AIRBAGS!!! hehe
     

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