need some help on cu ft of box

[mjshort18]

i am building a box for each of my 2 12kicker comp vrs and the recomended minimum sealed enclosure for these subs is 1 cu ft. the problem i am having is that i can only get about .7 cu ft the way i am wanting to set these things up and still leave room in the trunk for other things. i was thinking i could use poly fill and make the sub think it was in a 1 cu ft sealed box but i am not sure if that would be good enough. thanks

[EG_Civic]

polyfill throws off the air physics and should be good for your box. Use a pound for each cu. feet of volume. I use it and it works great.

[GSteg]

what's an air physics? lol.



polyfill will work, or it may not. depends on the application.

.7 cubes is really small for the kicker. Kicker gave a box size that would satisfy the average basshead, and the Qtc would be up around the 0.9 area. with the 0.7 cubes, you can expect it to be even more boomy than at 1.0 cubes. Kicker also recommend 1.0 cubes after all displacement i believe.

Wouldn't hurt to try polyfill though.

[mjshort18]

what is qtc? i think i am just going to try to make it at least 1 cu ft. are you saying that only one cubic foot would be boomy or how would it sound. in the manual for the subs it says that when the subs have 1 cu ft in a sealed boc it will let them perform at their maximum rms level. why is this and how will they sound? thanks

[GSteg]

They say that in the manual because they aim for the average customer. 1 cubes may sound ok for the average, but if you like SQ more than SPL, then they are a bit boomy. The inductance of the kicker will be high already, so naturally, its going to be boomy.

[droptop94]

hard to say what they will sound like with out building the box and hooking them up. speakers and amps have two power rateings. peak and rms. you want your rms power on the amp and the subs to be preaty close. you can use the the smaller box but the subs will not handle as much power as they would in the bigger box. the 1cft box will proubly produce the best sounding bass if you have your rms powers matched. i would use poly fill in both boxs. if you want to find the best sound build both boxs and try them out.

[GSteg]

smaller boxes will be able to handle more power (mechanically speaking) than bigger boxes.

[droptop94]

(physically speaking) bigger boxes handle more power. It takes more power to move more air in side the box and less power to move less air in side the small box their for smaller boxes handle less power. ask a install shop

[GSteg]

don't need to ask an install shop.

What you don't realize is that the cone doesn't move air. when the one moves, the air is being compressed. There is a spring action going on. The smaller the box, the more stiffer the air spring is going to be, thus having more force to keep the cone in a rest position.

That's physics. To prove my point further, if you're willing to participate, give me your subwoofer and i will build two boxes. 1.0 cubes and 3.0 cubes. I'll send it ~300w and you can decide for yourself which box makes the cone moves more. I am 99.9% sure that the bigger box will require less power to get to a specific excursion.

Otherwise you're defying the law of physics.

Another reason why SQ competitors only use less than 300w for their infinite baffle setup? Any more than that, most suspension would be slammed to the ground.

[mjshort18]

so 1 cu ft will get me boomier sound and say 3 cu ft will give me more sq. ok, i guess i get it. if the box is smaller and the "air spring" is stiffer then would't the bass produced be less boomy because the sub would move quicker and get back to the resting position faster for the next note of the music? just a thought, i could be totally wrong. thanks for the help guys.

[GSteg]

the acceleration of the cone does not change. What changes is the excursion. The more air spring you have, the less excursion you're going to have, in turns more mechanical power handling power.

the quickness of the driver is dependent on the inductance of the coil. The lower the inductance, the quicker the cone will move. Adire Audio has a tech paper on this issue.

[mjshort18]

ok so will it sound like i have as much power going to them if i make the box smaller?

[Seany B]

OK prolly stupid question but SPL and SQ? what do they mean?

[DeleriousZ]

SPL is a measure of sound pressure in decibles. SQ is a measure of sound quality (how clear the tone sounds, what the responce of the speaker is like, basically the overall pleasing to the ear sound)

[PaulD]

an SQ woofer,that's a good one