free air sub

[holdenboy]

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

long day

 

[Trent1291]

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...

 

[trentvy]

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.

 

[Trent1291]

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

 

[Not_An_Abba_Fan]

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.

 

[theSeekerr]

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.

 

[TrikkBen]

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!!

AIRBAGS!!! hehe