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alwaysontop
03-01-2008, 01:58 PM
i dont get it i have a box tuned right and big enough for two subs but can i really put two subs in it?

IgnoreMe
03-01-2008, 01:59 PM
first off, that calculator is somewhat in accurate. secondly, you can put 1000 subs in the box if they all get their proper volume.

alwaysontop
03-01-2008, 02:01 PM
well where do i get an accurate way to design a box because no one will come throught with a quick box design i just want to start building my box

IgnoreMe
03-01-2008, 02:05 PM
http://www.caraudio.com/forum/showthread.php?t=215849

or my link in my sig.

i doubt you'll do either, so ill say, just use the RE calculator.

alwaysontop
03-01-2008, 02:10 PM
ive read it over like 4,000,000,000 times and there are just parts of it i dont get. and even if i do try it im gunna be second guessing myself and if i end up making a box that ***** because of myself im gunna be so pissed

alwaysontop
03-01-2008, 02:15 PM
actually i just cant figure out the port length at all. i cant figure out how the hell to use winisd i dont know what half of it means

IgnoreMe
03-01-2008, 02:19 PM
actually i just cant figure out the port length at all. i cant figure out how the hell to use winisd i dont know what half of it means

do you have it open right now? if so, i can walk you through it

alwaysontop
03-01-2008, 02:21 PM
yeah i have it open when i start out alls it has is kicker L7's on there i have 2 kicker comp VR's how do i get passed that?

IgnoreMe
03-01-2008, 02:25 PM
1) open win isd

2) select new project

3) the first driver that comes up, just press next, next, then select vented for the box type, next, forget the alignments, and press next. you should now get a graph and a little box pop up

tip: you do not need to select the driver you are using to get port length. just select the first one it gives you

4) select box and put in your volume, and tuning you are going to use

5) select vents. there is a white circle there. if you are going to use a round port, leave it alone. if you are going to use a slot port, click on the white circle

6) change the vent diameter to the height and width you are going to use

do a 4^3ft box tuned to 35hz with 60^2 of port (15x4 in this case), and tell me what you got as port length.

alwaysontop
03-01-2008, 02:34 PM
it says the vent length is 26.61 in and the 15x4 or 60^2 is supposed to be in inches right? if it is thats what i got.

IgnoreMe
03-01-2008, 02:39 PM
26.46

close enough. the difference is usally because winisd will change the tuning (if you go back to the box tab) to like 34.8hz or something which will change the length and make them somewhat different.

so in this case you would use 26.5" (always easier to go to the closest 1/4", hell you can go to 1/8" if you want, but i usually dont) and be done with it. now if this is going to be a standard slot port that uses the side of the box as 1 side of the port then you also need to subtract half of the port width from the port length.

in our example, you have a port length of 26.5 and a width of 4". so your port length needs to be 24.5". this is called end correction and is used because having only one flange that is open (ie one side) causes the air to follow the side of the box that makes up the other side of the port. so you have to shorten the calculated port length, to get the physical port length. the subwoofer will "see" the calculated port length when its all said and done.

hope i didnt confuse you.

alwaysontop
03-01-2008, 02:44 PM
you didnt i understand that all i have to remember is just subtract half of the width from the port length. now i have one more question.

the only reason you subtracted that was because the port is on the left or right side and the subs on the other so it would kinda look like this
| | O O |
if i do my box like that the volume for one sub is 2.3 cubes.
do i multiply that by two to get the total volume i need for 2 subs or do i just keep it at 2.3 cubes?

IgnoreMe
03-01-2008, 02:47 PM
you didnt i understand that all i have to remember is just subtract half of the width from the port length. now i have one more question.

the only reason you subtracted that was because the port is on the left or right side and the subs on the other so it would kinda look like this
| | O O |

yes, as long as a port uses 1 side of the enclosure, you have to include end correction

if i do my box like that the volume for one sub is 2.3 cubes.
do i multiply that by two to get the total volume i need for 2 subs or do i just keep it at 2.3 cubes?

if you are going to use two subs, and each one requires 2.3 cubes (or if thats what you're aiming for) then you need a box that will be 4.6 cubes after all displacements (4.6 cubes net, not gross)



^^^^^

alwaysontop
03-01-2008, 02:48 PM
so 4.6 cubes after driver displacement and bracing right?

IgnoreMe
03-01-2008, 02:53 PM
so 4.6 cubes after driver displacement and bracing right?

correct.

after the subs get loaded in and take up some volume, after the braces take up some volume, and after the port takes up some volume, there needs to be 4.6 cubic feet of unused space for the subs ;)

alwaysontop
03-01-2008, 02:53 PM
and also another question how do i find the height and width of my port? like i can take the size that the manufacturer requires but you upped yours for some reason what is a good size for mine?

IgnoreMe
03-01-2008, 02:57 PM
and also another question how do i find the height and width of my port? like i can take the size that the manufacturer requires but you upped yours for some reason what is a good size for mine?

if you are doing a slot port, then use the internal height (or external height minus 1.5", if you are using 3/4" mdf) at your port height. then use your width to get the port area you want.

if the manufacturer says 2.3 cubes with a 3x12" port or something like that, you know they want 36^2 per driver. so just double it for 2 drivers.

now just divide that number by your height and that will give you your required width. input that data into winisd with your box volume and tuning, and viola, you have a port length.

alwaysontop
03-01-2008, 03:02 PM
well my internal height is 11.5 so i take 72 and divide it by 11.5 to get my width?

IgnoreMe
03-01-2008, 03:04 PM
well my internal height is 11.5 so i take 72 and divide it by 11.5 to get my width?

well, yes, if each sub is going to need 36^2. that was just an example. what does kicker really recommend?

also, 11.5"? will the cvr's fit? i dont know the cutout, but this does catch my eye.

alwaysontop
03-01-2008, 03:14 PM
yeah the cut out is 11 1/8

but this is what kicker reccmends
2.25^3 per sub
and they reccomend a vent side of
3"x12.5" port 20.5" long

should i just use those and tune the box to 32 hz (i heard 32hz) sounded the best with my subs

alwaysontop
03-01-2008, 03:15 PM
vent size* and that size is also with only one sub

IgnoreMe
03-01-2008, 03:18 PM
yeah the cut out is 11 1/8

but this is what kicker reccmends
2.25^3 per sub
and they reccomend a vent side of
3"x12.5" port 20.5" long

should i just use those and tune the box to 32 hz (i heard 32hz) sounded the best with my subs

wow! that would tune you to almost 42hz! yea i would definitely go much lower than that for daily.

shoot for 50-60^2 of port (total, ie 25-30 per), and a tuning of 32-35hz or so

alwaysontop
03-01-2008, 03:21 PM
see thats the part i dont get haha do i use 50 or 60^2 and what the heck does that make my height and width of my port?

alwaysontop
03-01-2008, 03:33 PM
ok my internal height is 12 so i took 60 and divided it by 12 and got 5 so 5 is my port width right?

alwaysontop
03-01-2008, 03:36 PM
ok so i got in winISD and i put 4.6^3 tuned to 32 hz and put 15" H an d 5" W and it got me a port length of 61.93 inches does that sound right?

alwaysontop
03-01-2008, 03:36 PM
ok so i got in winISD and i put 4.6^3 tuned to 32 hz and put 15" H an d 5" W and it got me a port length of 61.93 inches does that sound right?

IgnoreMe
03-01-2008, 03:36 PM
ok my internal height is 12 so i took 60 and divided it by 12 and got 5 so 5 is my port width right?

if you want to use 60^2 of port then yes ;)

there really isnt an equation for port area. its pretty much based on the characteristics of the driver. with a short throw driver and little power, you dont need lots of port area. with a long throw driver and lots of power you need more, and everything in between.

most of my drivers have been longer throw drivers with 3kw. so i would use 60^2+ (15" per cubic foot) for each 15" sub. its not necessary for all drivers.

alwaysontop
03-01-2008, 03:37 PM
ok so i got in winISD and i put 4.6^3 tuned to 32 hz and put 12" H an d 5" W and it got me a port length of 61.93 inches does that sound right?

IgnoreMe
03-01-2008, 03:39 PM
ok so i got in winISD and i put 4.6^3 tuned to 32 hz and put 12" H an d 5" W and it got me a port length of 61.93 inches does that sound right?

nope. 27.79 is the correct port length for that box.

sometimes you have to click back and forth between the tabs to make sure the numbers havent changed. if you get a super long port length, click back on the box tab and take a look at your tuning ;)

alwaysontop
03-01-2008, 03:40 PM
it came out so big because i changed the number of drivers to 2 i thought you were supposed to do that since i was using two subs?

well if i dont i rounded to 27.75 and subtracted 2.5 (half of 5) and got 25.25 as my port length correct? (if i wasnt supposed to change drivers to 2)

IgnoreMe
03-01-2008, 03:44 PM
it came out so big because i changed the number of drivers to 2 i thought you were supposed to do that since i was using two subs?

nope. dont change anything. the amount of drivers is not important in getting a port length, just leave it be.

from my tutorial:

http://www.caraudio911.com/tutorials/PortedBox/images/001.gif
Lv = port length (what your solving for)
Av = your port area (height x width of the port face)
Vb = the internal volume of your box
Fb = the tuning frequency you want

as you can see, number of drivers is not a factor that is used to calculate port length.

alwaysontop
03-01-2008, 03:47 PM
alright awesome i edited my last post and said that i took 27.75 and subtracted 2.5 (half of 5) and got 25.25 as my port length correct?

alwaysontop
03-01-2008, 03:59 PM
alright i think thats right so this is my absolute last 2 questions (i think) and i will finally understand how to design ported boxes haha my driver displacement says its 122.1 cubic inches how do i change that to cubic feet so i can add that to my port displacement and my desired net volume? do i divide it by 1728?

also when i was getting my port diplacement it came out to 1^3 does that sound right?

alwaysontop
03-01-2008, 04:14 PM
anyone!?!?! can anyone tell me how to figure out my displacement its the only thing i need to know so i can start building this ***** box !!!!!

IgnoreMe
03-01-2008, 04:16 PM
.07 cubes.

IgnoreMe
03-01-2008, 04:19 PM
alright i think thats right so this is my absolute last 2 questions (i think) and i will finally understand how to design ported boxes haha my driver displacement says its 122.1 cubic inches how do i change that to cubic feet so i can add that to my port displacement and my desired net volume? do i divide it by 1728?

also when i was getting my port diplacement it came out to 1^3 does that sound right?

1.1^3ft is the port displacement.

27.75 x 12H x 5.75 (port width, plus the actual piece of 3/4" mdf that makes up the port wall on that side)/1728

its nothing major and wouldn't really amount to anything, but im just showing you the little things.

alwaysontop
03-01-2008, 04:25 PM
so .07^3 is my driver displacement?

IgnoreMe
03-01-2008, 04:27 PM
so .07^3 is my driver displacement?

yup.

thats actually a pretty common displacement for a lot of commercial 12" drivers. you have some outliers of course.

ngsm13
03-01-2008, 04:29 PM
http://www.caraudio.com/forum/showthread.php?t=215849

or my link in my sig.

i doubt you'll do either, so ill say, just use the RE calculator.

I would use subwoofertools over the RE calculator... it *****...

nG

IgnoreMe
03-01-2008, 04:31 PM
I would use subwoofertools over the RE calculator... it *****...

nG

is it really that bad? i saw some posts about it a while back, but i didnt get to much into them because i usually just design my own.

i think its a lot more fun to do it yourself too ;)

alwaysontop
03-05-2008, 08:43 AM
thanks for all the help IgnoreMe i really appreciate it. i came up with a pretty good box. not as nice as i would like but it works and it is a lot louder.