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J

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Discussion Starter #1
So I've heard that a sealed box is good for a pounding, and a ported box is good for a defined bass reproduction. I currently have 2 12" JL W3 D4 subs but no box. I won't be blasting my ears off like I used to a couple of years ago. I am more into the defined sounds now. So the question is, would a ported box do nicely in a wagon or should I still stick to a sealed box? I have no experience with ported yet. Thanks guys,
 
N

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Discussion Starter #2
It really depends on the model of subwoofer you're using. Different subs like different kinds of boxes.

With your W3s, a sealed box is your fastest ticket to quality bass. The sound will be nice, tight, and snappy. Ported boxes put out a lot more low frequency sound (aka BOOM), and the sound can be a bit sloppier than that from a sealed box. Ported CAN sound good, if the box is designed properly and built perfectly, however.
 
O

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actaully thats the other way around. ported will give you a better sound around a certian hertz level. whichever the port is tuned to. the seal is better because it reacts better to quick bass like that in rock music or other types of music. a sealed box is also more forgiving than a ported box if you turn it up too loud.
 
A

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Discussion Starter #4
Originally posted by ophidia31:
ported will give you a better sound around a certian hertz level. whichever the port is tuned to.
Que? Not sure what you are refering to, I assume you are talking about efficency at the tuning frequency? If that is the case, you will get more output, not necessarily better sound, the closer you come to the vent frequency. Both types of enclosures can sound incredible, but ported is less forgiving of miscalculations and construction errors. If ported sound worse than sealed, why do most high-end home theater manufacturers use ported enclosures for mid/midbass enclosures, getting the frequency response down to 50hz typically.
 
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Discussion Starter #6
because high end home theater companies take the time and r and d to get port lengths down to the specs that they want them to and also to make them sound the way they want them to. but were not talking about hometheater systems here. a car is a different ballgame. its hard to get a subwoofer/midrange to sound the way they want it to in a different variety of cars since everything is so close together and many different contours. where as in a house youre sitting farther way from the speakers. yeah, they can be made to sound really good, but overall and ease of installation a sealed box is the way to go.
 
C

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Discussion Starter #7
i'll say go ported, the box will be bigger, but you have a wagon so that shouldn't be a problem. use the specs that jl gives you, and build the box to those exact specs. that should give you the best sound, i've built jl vented boxes to spec before and they sounded great. also make sure you've got a really nice amp aswell, thats going to help alot with your sq that your looking for.
 
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Discussion Starter #8
Originally posted by ophidia31:
but were not talking about hometheater systems here. a car is a different ballgame.
A car is a different ballgame when you talk about how the enclosure reacts with the vehicle, but all standard subwoofer enclosure design theories and practices still apply.
 
J

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Discussion Starter #9
Thanks all you guys. I'll buy that ported box next month.
 
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Discussion Starter #10
FWIW: IMO Sealed boxes are my favorite. I have bought and built every diffrent kind of box (sealed, bandbass, ported, etc) and Every time I have built a new sealed box afterward..

I totally agree it really depends on your subwoofer aplication, but If you can choose from freeair or sealed, I would go sealed..

Thats my 2 cents worth...
 
C

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Discussion Starter #11
sealed boxes are great, but if you have a speaker that can be used in vernted boxes, and you build the box exactly to spec the box will be louder and sounds better then your sealed box. imho i wouldn't go out and buy a prefab ported box, if you are going to do that you might aswell just used sealed. because that prefab isn't going to be build to the right specs most likely and will probably sound like crap. when my ppi pro 12's show up in the mail, i am going to go ported with that box.
 
C

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Discussion Starter #12
A good friend of mine owns a car audio shop, and I have heard this question many a times.....

1. sealed
2. ported
3. bandpass

Go with a sealed box, unless you only listen to one type of music in a certen htz range. a ported will only sound best in the frequency that the port is designed for. same with the bandpass only worse. where as a sealed box is made just for the airspace of the speaker, and not a certian frequency.


BUT if you decide that you absolutly have to have a ported box, go with the 5th dimention box (aka the one you have pictered above). good luck in what ever you decided to go with....

matt
 
J

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Discussion Starter #13
Thanks Matt. I am going to experiment between the box I posted and a sealed box later on down the road. I am not looking into playing it loud like I used to, just want the bass to be more defined. I think I am growing out of the big bass crowd lol but we'll see
 
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Discussion Starter #14
Abe Cohen's book, along with the one by Martin Colloms, shows the tradeoff between the sealed cabinet vs ported cabinet. There are, of course, many others.... probably going back to N.W. McLachlan's book Loud Speakers from 1934.

The ported cabinet uses the backwave from the loudspeaker to excite a Helmholtz resonance of the port-cavity combination, with the cavity being the volume inside the box. The cavity is the spring and the mass of air in the port is the mass, forming a spring-mass system. The resonance is usually designed to beef-up the loudspeaker response below the mechanical resonance frequency of the cone, because the sound level would ordinarily be reduced by the stiffness control of the cone (for you engr/physics types, stiffness control below resonance, mass control above resonance, and damping control at resonance).

The tradeoff in using the ported enclosure is that there is a phase shift between the port resonance and the cone resonance, so that the combined acoustic waves leaving the enclosure in-between these frequencies isn't entirely constructive.... so there is some cancellation of sound.

The upshot for the ported design is that you can get a boosted low-frequency response, but you do so at the cost of losing some smoothness in the system response.... unless the designer is very careful.

That's why it is MUCH easier to make a sealed enclosure -- there isn't much to screw up. With that said, a car interior is a nasty place because it's so darn small, so it's difficult to make smooth audio anyway, nevermind the road & exhaust noise. So there is some merit in not worrying about smoothness, and making a smaller-sized ported enclosure.

Beyond that, it becomes a matter of cosmetics, cleverness of the deisgner in making the box fit within the car, and snob appeal. Which is where I leave this discussion... <g>

Here are a few links for the DIY loudspeaker builder:

http://www.audioxpress.com/magsdirx/ax/index.htm

http://www.audioxpress.com/magsdirx/index.htm

http://www.audioxpress.com/bksprods/bookindexl.htm

HTH, FWIW. - Ken
 
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