these box calcs seem right?

[wu501 10+ year member]

I got a 15" RE SX coming in tommorow and i want to get started on building a ported enclosure for it.

here is what I came up with:

box dimensions: 30x18x17=5.31 external/4.21 internal.

port:3"(w) x 16.5"(h) x 37.5(l)

=3+.75 x 16.5 x 37.5 = 2320.31/1728=1.3427

box: 4.21-1.347(port) - .18 (sub)=2.683 cubes tuned to 27 hz?

I know i still need to account for a little bracing, but does this sound right?

Click to read more...

 

[OLD_SCHOOL 10+ year member]

no doesn't seem right check port displacement

 

[jellyfish420 10+ year member]

i got (with the same box and port dimentions) port length 41.75inches and about 3 ft^3

 

[wu501 10+ year member]

werd, scratch the above post i made. I realized what i calculated wrong and ended up goin with 4 cubes tuned to 30 hz. This is the new box design:

box dimensions-28"w x 22"d x 18"h= 4.8125

port-3 x 16.5 x 25

Withe the port/sub/bracing dispacement i came out with about 4 cubes tuned to 30 hz.

Is this correct?

 

[jellyfish420 10+ year member]

28*22*18=11088in^3

11088/1728=6.41ft^3

or if these are internal specs=5.187ft^3

your box does come to about 4ft^3 but tuned to 33-34Hz not 30

port length should be 42" long

 

[wu501 10+ year member]

where did that number come from for the port length? im using winisd and after putting in the 5.187 volume tuned to 30hz and the 3" X 16.5" port, it gives me a 22.65" long port. Anyone else?

 

[XTRMEASURES 10+ year member]

winisd sucks, now dont get me wrong its a good program that its free but.... remember its free so you only get what you pay for....

ok this is what i got ....

box external size: 28w X 18h X 22d =5.187

port size: 3h X 16.5w X 42d gives you a tuneing of 35.8hz, now at 60 it gives you 30.5hz

port area: 49.5sqin which is real good for a sub like that

displacement sub/port: sub .18cuft/port 2.63cuft

now that gives you a internal box size of 2.38cuft

for a 15" sub id go alittle bigger if you could, but this box should sound and hit real nice with the right power pushing it....

now i did this kinda fast but i think its right ill checvk again later when i have time.......

i dont usely do this for ppl but heck im bored right now....i have my reasons.......hehehe

good luck

jamie

 

[wu501 10+ year member]

so about 60 inches long? thanks for the help? Seems a bit long, but ive only built one other ported box so who knows. What program did you use anyway?

 

[OLD_SCHOOL 10+ year member]

if your port is in an L shape fashion you port displacement is wrong

displaceemnt is down the middle of the physical port length

 

[jellyfish420 10+ year member]

where did that number come from for the port length? im using winisd and after putting in the 5.187 volume tuned to 30hz and the 3" X 16.5" port, it gives me a 22.65" long port. Anyone else?

i used BBP6

 

[wu501 10+ year member]

so ive gotten a few different answers now. The port is an L shape. How long must the port be?????

 

[OLD_SCHOOL 10+ year member]

http://www.caraudio.com/vb/showthread.php?t=67594&page=1&pp=15

http://www.caraudio.com/vb/showthread.php?t=68332

read these if you don't get it then pay jmac a few bucks and he will draw one up for you

 

[wu501 10+ year member]

well thanks for the help but i was hoping someone could give me a definite answer. You see the box is half built already so i needed this info asap. The first wall of the port is already in and its 3" wide and 16.74 long and now i gotta put in this second port wall. I thought i had the right calculations before i satrted building but now some people are telling me otherwise.

 

[OLD_SCHOOL 10+ year member]

is it to hard to start over ?

you will be much happier with a box that is done right then one that isn't

 

[wu501 10+ year member]

no its not too hard. I just thought i had it right and after building most of the box, i really dont feel like going and spending another 25 bux for a sheet of mdf and i really dont have that much extra time to do it. Im not trying to be lazy, i want it done right. I just want to know what i need to make the port length overall in this box to make it work with it being 3" wide and 16.5" tall. I guess im asking too much. Sorry to trouble anyone....