ported box questions....

[traksta15 10+ year member]

ok, i have a few questions to ask about building a ported box.........

1. when calculating GROSS box volume, isn't i just l x w h?

2. when calculatin NET box volume isn't it l x w x h MINUS the l x w x h of the port MINUS sub displacement? (accounting for wood thickness of course)

3. say ur port has to be 35" long, and ur port is 10"h x 5"w, don't u make it 2.5" shorter physically due to end correction cause the sub can't see the port, it only feels it...correct me if im wrong on this i thought u just subtractedhalf the width from the physical port length....

any help would be greatly appreciated, and thanks again to all the people in this forum who have helped me........TIA

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[traksta15 10+ year member]

bump.......

 

[traksta15 10+ year member]

oh come on, u no u no the answers.....

 

[ANeonRider 10+ year member]

ok, i have a few questions to ask about building a ported box.........
1. when calculating GROSS box volume, isn't i just l x w h?

2. when calculatin NET box volume isn't it l x w x h MINUS the l x w x h of the port MINUS sub displacement? (accounting for wood thickness of course)

3. say ur port has to be 35" long, and ur port is 10"h x 5"w, don't u make it 2.5" shorter physically due to end correction cause the sub can't see the port, it only feels it...correct me if im wrong on this i thought u just subtractedhalf the width from the physical port length....

any help would be greatly appreciated, and thanks again to all the people in this forum who have helped me........TIA

1. Yes

2. Net = internal volume, so it is the internal LxWxH(which is the outside dimensions minus the wood thickness) minus the sub and port displacement.

3. That is correct.

 

[traksta15 10+ year member]

ok, thanks a lot, i knew someone would come through with help.......

 

[traksta15 10+ year member]

http://img195.exs.cx/img195/4881/goodbox4yp.gif

hey neonrider, does this box look good??i needed at least 3.5 cubes total, with adequate port area, tuned to 33 hz......is there any chance u can check it for me?

 

[ANeonRider 10+ year member]

ya, ill do it a little later. I'll let ya know.

 

[Moe Lester 10+ year member]

you didnt count in the wood thickness of the port, your box is 11 tall, the port is 4 tall, but you listed the depth above the port as 7", thats 2.25" of wood that is unaccounted for.

 

[traksta15 10+ year member]

ok. here's the new design accounting for wood thickness in my port

http://img212.exs.cx/img212/9999/project15dg.gif

yes, no???

 

[ANeonRider 10+ year member]

How high is the box? How deep is your sub? From that picture it can't be any deeper than 3".

 

[traksta15 10+ year member]

it goes along with the 1st pic http://img195.exs.cx/img195/4881/goodbox4yp.gif

just accounted for wood thickness-i hope.......

 

[ANeonRider 10+ year member]

Still don't have enough depth to fit the subs in there....

 

[traksta15 10+ year member]

hey, it doesn't matter where the port goes right? i did a search and some said it didn't matter, some said u only do it in pure spl setups.....any insight?

 

[ANeonRider 10+ year member]

Doesn't matter.

 

[cappy72 10+ year member]

Ok I have a question here ... how do you figure out the port dimentions??? I know how to get the width of the port and the actual length of the hole but the "L" shape that you have there I dont know how to get... can anyone help???

 

[ANeonRider 10+ year member]

Length in a L shaped port is determined by the length of the middle of the port. If it uses an outer wall, then minus 1/2 of the width of the port for end correction.

To figure out the port dimensions you need, you need to use a bunch of formulas that can be found here:

http://forums.caraudio.com/vb/showthread.php?t=74715

 

[cappy72 10+ year member]

I saw that link but I didnt fully understand it...

so your saying to take the middle of the ports width and measure the length, say from top to bottom????

is that right>> .cause that should be the same as the length on either one of the sides???

 

[cappy72 10+ year member]

or are you saying that if I have a port width of 4 inches and a length of 15 inches then I subtract 2 inches from 15....

do you think it would be best for me to ask someone to blueprints??? this is my first ported box...

 

[traksta15 10+ year member]

i'm still a newb at box building, but i'm pretty sure you just extend the port down ur box, and bend it at the distance from ur back wall (ur width). If u have a 3" wide port, u bend it 3" from the back wall, and continue on with the rest of ur port length. Remember to account for wood thickness.....

 

[cappy72 10+ year member]

ok that i understand and infact I have heard that somewhere else as well... so I would want a port length of depth and then anothe port length for the base of the L right???