# how do u calculate cf for fiberglass box?

diverdown269
Member - Posts: 10
Joined: July 12, 2009
Location: Kentucky, United States
Posted: August 04, 2009 at 1:57 AM / IP Logged
With all the curves, How do you calculate the area of the enclosure on a fiberglass box ?
Some fear the Abyss... Other, chase it into the DEPTHS !!!
ianarian
Copper - Posts: 516
Joined: April 24, 2009
Location: California, United States
Posted: August 04, 2009 at 2:30 AM / IP Logged
I know a guy who will take a large garbage bag, set it in the speaker hole as if it was a trash can. He fills it with water then vacuum's out the water in a shop-vac. Then dumps it in containers to get the volume by liter. Professionals use the ol' "eye ball" method-experience. I rebuild until Im satisfied. Another guy I know uses beach sand then shop-vac, which always was weird to me....the enclosure is done, whats it matter now?
This is what I do for FUN!
i am an idiot
Platinum - Posts: 13,605
Joined: September 21, 2006
Location: Louisiana, United States
Posted: August 04, 2009 at 7:28 AM / IP Logged
Build a box without a top on it.  Make the inside dimensions 12 X 12 X 12.  Find a worn out bean bag chair or some shipping peanuts.  Cut the bean bag chair open and dump the pellets into the sub enclosure..  Or the shipping peanuts into the sub enclosure.  Fill the enclosure with whatever material you can.  Scoop it out and place into the 1 Cu. Ft enclosure you built.  When it is full write a line on the side of the little box and empty it.  Repeat until the sub enclosure has no more material in it.
Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB
vibrationcustum
Copper - Posts: 171
Joined: April 05, 2009
Location: Michigan, United States
Posted: August 05, 2009 at 11:14 AM / IP Logged
i am an idiot wrote:
 Build a box without a top on it.  Make the inside dimensions 12 X 12 X 12.  Find a worn out bean bag chair or some shipping peanuts.  Cut the bean bag chair open and dump the pellets into the sub enclosure..  Or the shipping peanuts into the sub enclosure.  Fill the enclosure with whatever material you can.  Scoop it out and place into the 1 Cu. Ft enclosure you built.  When it is full write a line on the side of the little box and empty it.  Repeat until the sub enclosure has no more material in it.
Great way I am a idiot, Done this many times. Great job
Can't be loud then don't have it.
(power acoustik system)
ovn1-5500d 09 and another one coming soon
4-12" mofos 12ft3 box to 40hz (wall)
2 batterys, 1 power
Copper - Posts: 144
Joined: January 15, 2006
Location: United States
Posted: August 12, 2009 at 7:38 PM / IP Logged

Diverdown, in SO many cases there are way too many curves in an enclosure to actually calculate.  So filling a 12 x 12 x 12 square box with some time of lightweight media is the first and easiest thing to do.  I havent read this thread in a few years so here it is.... https://www.the12volt.com/installbay/forum_posts.asp~TID~41102~PN~1

You ask about calculating though.  Lets say you need to make an enclosure that contains 1.25 cu. ft of volume.

We know 12 in. x 12 in. x 12 in. = 1728 cubic inches (aka...1 cubic foot).  Also 1728 divided by 0.25 is 432 cubic inches...add your 1728 and you have a total of 2160 cubic inches to be 1.25 cu.ft.  Make a mark 3 inches up from the bottom of the box.  When you fill the box full of media you know that you have 1 cu.ft. volume of measuring media...you then empty it into a "semi-fabricated" enclosure...but you need that extra 432 cu.in. of media...so fill your the 12x12x12 box up to the 3 inch mark, thats the additional amount (432 cu.in.) of media you would have to add to total 1.25 cubic ft.  (Make a mark 6 inches high would of coarse be 0.5 cu.ft.  A mark 9 inches from the bottom would be 0.75 cu.ft.....and so on.)

....sorry if you knew all of that, but you asked.  :)

## Sorry, you can NOT post a reply.This topic is closed.

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot delete your posts in this forumYou cannot edit your posts in this forumYou cannot create polls in this forumYou cannot vote in polls in this forum

•
 Search the12volt.com