bigger box = lower bass???

[helotaxi 5,000+ posts]

LOL!!
Mannnn.. I tried that site, and it told me I need a 4.9 cubic feet sealed enclosure, and get this, a 9 cubic feet ported enclosure. lol. The sub's VAS is only 4.2 cubic feet. I think that site needs some repairs. The other calculators I tried were right on though.

Thanx again for the link, there was some helpful stuff on there.

Depending on the alignment of the enclosure, the box size can vary greatly. Mess with the Q for the sealed box. Higher Q means smaller box. Taking the Q from .7 (smoothest response anechoic) to between .9 and 1.0 (prefectly acceptable in the car) can reduce the enclosure size by more than half.

 

[marcus78 10+ year member]

hey go down to your doller store and get some cotten. fill the box all the way up with it.

 

[454Casull 10+ year member]

Tightness doesn't necessarily mean accuracy. One user pointed out that a smaller sealed box was "tighter". I believe what he is referring to is that hump in the midbass that the higher Fb gives. However, true-to-signal accuracy is improved when the box size is increased, as shown here. Qtc goes down with a larger box, and vice versa. I don't know much about vented boxes, but I think with a lower tuning frequency, impulse response is improved (to be fair, some people do enjoy the hump of underdamped tuning).

 

[454Casull 10+ year member]

helotaxi - IIRC sealed boxes exhibit a roll off at the rate of 6dB/octave, whereas reflex designs roll off at 12dB/octave. I could be wrong. Actually, I probably am. :beer;

 

[ImaLegacy 10+ year member]

so lets says.........i have a 2000 watt mono block amp hooked up to 2 12's......would i get a sloppier sound in a ported box then in a enclosure if the demensions are the same and everything

 

[BDIDDY 10+ year member]

so lets says.........i have a 2000 watt mono block amp hooked up to 2 12's......would i get a sloppier sound in a ported box then in a enclosure if the demensions are the same and everything

That would be slightly true but it depends on what subs you use, what you tune the box to, how big the ported box is, etc...

 

[helotaxi 5,000+ posts]

helotaxi - IIRC sealed boxes exhibit a roll off at the rate of 6dB/octave, whereas reflex designs roll off at 12dB/octave.

At optimal alignment, that is ususally correct. B4 alignment for ported and 0.707 Qtc for sealed. As you stray away from that, the roll-off rate changes as well. A larger box with a lower Q will roll off more gradually. A smaller box with a higher Q will drop more quickly.

The link you posted is for a speaker in an anechoic environment. The car is far from that. Because of the small air volume in the car itself, it will affect the alignment and the Q of the sub. You will get some loading from the air in the car, which can have the effect of lowering the Q. That is why you can get away with a higher Q in the car than in a large room environment. I don't know of a program that accounts for the loading of the vehicle but I remember that LEAP was working on it (and they have been for some time). There are just so many variables that you can't really account for when you start working in a small room environment.

 

[pavengmike6 10+ year member]

And who thought you could slap a few pieces of wood together and make a box. LOL

 

[helotaxi 5,000+ posts]

Well if it has six sides and encloses an air space it would be a box //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif...