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View Full Version : Bigger box, more port area = more SPL?



prochobo
05-01-2006, 07:00 PM
I remember reading something about this somewhere, but I forgot the exacts. In general, does a bigger box and more port area = more SPL?

Reason I want to know is because I'm pushing 2 12" Type-Rs in a 4.7 cube @ 35hz box. It has a crappy slot port, 41.6 ft^2 of port.

If I build a box about, say, 6 cubes with 4 or 6 4" aero's, in general, would there be an increase? Or is it just all car/install dependent?

Keep in mind, I just want the general rule of thumb. Thanks!

Trey803
05-01-2006, 07:28 PM
It will but to a certain point and then once you cross that point it will sound like shizzle. Tcab does a good job of making plans for boxes that will give you the most spl you will ever get out of those subs. I am guessing sq is no deal to you. I would not recomend building a box unless you have used a box calculator or i would recomend talking with tcab.

Insomniac119
05-01-2006, 07:36 PM
I thought that the bigger the box the better it sounded?

lilmaniac2
05-01-2006, 07:39 PM
bigger boxes can make ineffecient subs more effiecient there for making them louder on smaller amounts of power

photocrazy8
05-01-2006, 07:42 PM
I thought that the bigger the box the better it sounded?


much more to it than just that, read the sticky about boxes

prochobo
05-01-2006, 07:42 PM
It will but to a certain point and then once you cross that point it will sound like shizzle. Tcab does a good job of making plans for boxes that will give you the most spl you will ever get out of those subs. I am guessing sq is no deal to you. I would not recomend building a box unless you have used a box calculator or i would recomend talking with tcab.

Hmmm, I will give that a try, but will Mark be willing to give away his secrets? ::GASP::

skadude016
05-01-2006, 07:46 PM
Hmmm, I will give that a try, but will Mark be willing to give away his secrets? ::GASP::
for a price lol I think there around $300

prochobo
05-01-2006, 07:55 PM
for a price lol I think there around $300

Meh, I've been quoted by him already. I say screw that, I'm more of a "Do it yourself" kinda guy. Besides, I take pride in my work and I like saying that I built it rather than bought it. Plus, to everyone who's built boxes, the satisfaction you get after building it = win win win :D

Soooooo, can anyone answer my question? I'm gonna do 6 cubes and 4 4" aeros.

bobo244
05-01-2006, 10:30 PM
download a box building program, like WINisd, and plug in the numbers and it will tell u everything

watts
05-01-2006, 11:09 PM
Minimum cross sectional area for a port is critical. It is based on you sub parameters. If a ports area is to small then you sub has to gasp for air kinda like sucking hard through a straw. If they are large enough then you subs don't have to work as hard and you get more bang for the watt. If you get to large then you get non laminar air flow (Reynolds number greater than 2000) in the vent and your sub has to work harder. Flaring helps reduce this. Its the difference in aerodynamics of a jeep and a corvette. If the box is to large then it is as if the sub is running free air (do they still make them I haven't seen any in years.). If it is to small then it increase the damping of the woofer and in the SPL world this is very bad because it slows down the woofer speed and increase its time it takes to produce a wave (transit response).

PV Audio
05-02-2006, 08:45 AM
Minimum cross sectional area for a port is critical. It is based on you sub parameters. If a ports area is to small then you sub has to gasp for air kinda like sucking hard through a straw. If they are large enough then you subs don't have to work as hard and you get more bang for the watt. If you get to large then you get non laminar air flow (Reynolds number greater than 2000) in the vent and your sub has to work harder. Flaring helps reduce this. Its the difference in aerodynamics of a jeep and a corvette. If the box is to large then it is as if the sub is running free air (do they still make them I haven't seen any in years.). If it is to small then it increase the damping of the woofer and in the SPL world this is very bad because it slows down the woofer speed and increase its time it takes to produce a wave (transit response).
:uhoh: Scientific research to back up this claim?

PV Audio
05-02-2006, 08:46 AM
And by the way, acoustic suspension systems don't make the woofer slower than a ported box, where the hell did you get this bullshit from?

_DjScrew_
05-02-2006, 08:48 AM
yea as said before, you can only make a sub so efficient. once the box gets so big, you get the opposite of what you want.

dkguitarist
05-02-2006, 08:59 AM
yea as said before, you can only make a sub so efficient. once the box gets so big, you get the opposite of what you want.

x2. you're sub will start bottoming out and push itself past it's mechanical limits.

at this point, all you can do is mess with tuning frequency/port area. also be careful about port noise. :fyi: