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3.0 cubic feet sealed

 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 322
Registered: Jan-05
i have finally decided on 3.0 cubic feet sealed for my atlas but i can't get the dimensions right, every time i calculate the size of the box its always too big or too small. so can any1 help me out and just give me the dimensions. or mabey im just calculating it wrong cause this car audio book i have says to times the length/height/width then divide by 1728. is that the correct way?
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8686
Registered: Dec-03
an atlas what? 18"?
3cu ft is good for a sealed 18" sub
if it's a fifteen, you'd be fine with 2.5cu ft after driver displacement.

LxWxH for colume, + driver disp.
 

Bronze Member
Username: Legacyaudio

Post Number: 82
Registered: Feb-05
well considering a cu foot = 1728in then yes once u find the volume of your box to convert it to cu ft u would divide by that
not a very hard concept-- read the manual to your subs and it should tell u the dinesions
 

Silver Member
Username: Scubasteve

Annapolis, MD

Post Number: 282
Registered: May-05
normally when I make boxes, I pick out the critical dimensions first. I'll set any dimensions I can first, and then leave maybe 1 axis to determine using a simple l*w*h forumla. The key is, if you want a 3' cubed box, when you multiply all inside dimensions (in inches), you should get 5184. Most of the boxes I build have atleast one angle so its a little bit more difficult but its all really 8th grade geometry, nothing complicated.
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 323
Registered: Jan-05
ya its a 15, and i haven't taken geometry yet, thats next year, i have heared that you should make the box be a rectangle not a square because it causes cancallation is this true?
 

Silver Member
Username: Scubasteve

Annapolis, MD

Post Number: 296
Registered: May-05
true, it is best to avoid a perfect cube, although standing waves really can't be generated in a relatively small box with a sub thats crossed over at ~100Hz. 3 cubic feet is pretty big though, just don't make it abnormally deep. angling the front or back would also be a good idea, but may require a class in geometry, but idk.
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 325
Registered: Jan-05
ya my school is weired they make you take algebra 1 before geometry, also how much space will the sub take up, i think its called sub displacement, i was thinking .2 or .3 cf. and what if the sides of the box was angled, would this help take out the standing waves thing.
 

Anonymous
 
yur 17 and u havent taken geometry yet...wow...im 17 and im taking AP calculus...
 

Gold Member
Username: Invain

Michigan United States

Post Number: 3310
Registered: Aug-04
You do understand that some schools have their math courses in different order? Even though most schools have Geometry right after Algebra I, some do have it later instead.
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 326
Registered: Jan-05
ya i'm only in the 10th grade, and in our school it goes algbra 1, geometry, algebra 2, pre-calculuss, calculuss. and plus i had to retake pre-algebra so that put me behind even more.
 

Bronze Member
Username: Infinity_addict

Santa Rosa, California USA

Post Number: 41
Registered: Jul-05
watch your backs, people - we have a genius on our hands! anonymous is almost TOO smart!

who brags about their math class?

yes, dividing by 1728 would be correct, and make sure you measure by the inside dimensions of the box. good luck fellow DIYer!
 

Silver Member
Username: Scubasteve

Annapolis, MD

Post Number: 300
Registered: May-05
Dustin, if i remember correctly, you never mentioned what sub this was. Most companies give you the gross recommended volume, which already takes into account the volume of the woofer. Also, this is a gigantic box. You should probably port this. Since its a 15, I'm guessing your not trying to set any records for sq, so you might as well port it. Most people find ported boxes better (aka louder).

Anyway, if you were to make a trapazoid box, what you'll have is a different depth for the box depending on if you measure it at the top or bottom or anywhere in between. For calculating volume, average the depth at the top and the depth at the bottom and pretend that the number you calculated is the same as the depth for a rectangluar box.
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 327
Registered: Jan-05
well would port it but i have 2 subs and space is kinda small, going in the back of a jeep, the sub is a Ascendant audio atlas so i hope it has good sq. and on the site it was recomenneding boxes with 6 cubic feet, but there is no way i can go that big. how deep should i make to box, just enough to clear the magnet, or should i make it deeper so it can cool off a little bit more.
 

Bronze Member
Username: Jechapk

Post Number: 14
Registered: Jun-05
yeah i took ap cal at 15 because the stupid school didnt let me take it until 11th grade ;[
make the box as big as you can...from what i hear unless it is 3 or 4 times over recommended size it doesnt matter....
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 335
Registered: Jan-05
BUMP
 

Silver Member
Username: Scubasteve

Annapolis, MD

Post Number: 309
Registered: May-05
an inch or so of breathing room wouldn't be a bad idea. Plus, if this is your first box, you don't want to leave "just enough to clear the magnet" because undoubtedly, something will be off by a quarter inch and the sub no longer fits.
 

Silver Member
Username: Letto

Milwaukee, WI

Post Number: 105
Registered: Jun-05
What is this world coming to when people start bragging about their Math classes... Especially in a forum with people like myself (an engineering major with a math minor) that have taken more Math than most people care to think about.
 

Bronze Member
Username: Halby

Parsippany, NJ

Post Number: 76
Registered: Jun-05
Word Letto same here, I feel ya.
 

Silver Member
Username: Scubasteve

Annapolis, MD

Post Number: 312
Registered: May-05
anyone else find that ironic? :-)
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 341
Registered: Jan-05
ya just a little bit, but thanks for the advice i'll start building the boxes as soon as i get some mdf board, i'll post some pics when i get done but that may be a while. ohh would i notice a difference if i used 1 inch mdf board or would 3/4 be good enough.
 

Silver Member
Username: Scubasteve

Annapolis, MD

Post Number: 314
Registered: May-05
3/4" might be a little thin for a 3 cubic ft. box but if its well braced you'll be fine.
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 345
Registered: Jan-05
well i'll just go with 1 inch just to be safe.
 

New member
Username: Modder05

Brooklyn, Oh

Post Number: 4
Registered: Jul-05
3/4" MDF properly glued and sealed will do you you plenty of justice....box design of that caliber should be constructed as a wedge.....if you are having a hard time with the measurements then try a program like Probox5....its cheap, downloadable and simple to use.....ebay has a downloadable version for 3.00....if you order it punch in these figures and it will give you a wedge box that has a volumn of 2.98..(W-25", D-24", H-18", Top-8.25", 3/4"mdf board) you can play around with those figures based on clearance in your car or truck! And it will also give you a breakdown of each peice to cut, and what dimensions to cut them at! Good Luck!
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 4329
Registered: May-04
bcae offers a free box tutorial.

http://www.bcae1.com/spboxnew2.htm

Just play around with it until you get the dimensions needed to fit, it's very straightforward.

3/4" would work, but bracing is always a good thing, you could either brace, or you could build from 1", or use 1" and brace (<- best thing).
 

Silver Member
Username: Cenus

Hicksville, Ohio Usa

Post Number: 350
Registered: Jan-05
cool thanks for the site its very helpfull
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