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brokeitagain
11-18-2007, 07:15 PM
ok i borrowed this pic from fischer customs.
how do u figure the tuning on a box that uses a shared port in between the drivers. I am hoping for a detailed explanation. thanks
http://img.photobucket.com/albums/v238/brokeitagain/Sean20Burnette20032.gif


I hope fischer customs does not mind me using their pic.
That guy builds some nice stuff

dan5505
11-18-2007, 07:44 PM
You could throw all of the specs into here http://www.subwoofertools.com/forum/ported-box.asp
or winisd. Then just adjust the tuning frequency until everything matches up right.

brokeitagain
11-18-2007, 08:03 PM
i would much rather get a technical explanation of how properly figure it. i dont want to trust some online calculator that may be way off.
i want to know how to figure the volume and tuning of an enclosure like the one that is pictured above. i know how to do it if the subs are in the same chamber but is it different when the enclosure is built as the one above?

dan5505
11-18-2007, 08:14 PM
As far as I know, most people use the online calculator or Winisd. I may be wrong though. I have no clue how you would calculate the tuning out by hand. I would kinda like to know that myself. Even though the two chambers in your picture are separated, they share the same port. Again, I may be wrong, but i think you can calculate it just as if the two chambers were connected. Use the combined volume of the two.

brokeitagain
11-18-2007, 08:16 PM
thats what i was thinking originally. Now i think that it is supposed to be two separate chambers then figure the port in somehow
thats where i am lost at.

i am trying to figure out the tuning on the box i might buy to use with the new subs i bought. The audio shop says it is built for these but( i know that they did build it)i want to know what it is tuned to before i spend 60 bucks on it. If its not what i want i will build my own to suit my desires

RAM_Designs
11-18-2007, 08:21 PM
Just plug in the internal volume of your box(minus port/subs), port area, and port length into a calc and it'll tell you the tuning frequency. There's nothing special or tricky to having two subs and one port.

dan5505
11-18-2007, 08:22 PM
If you were to calculate them separately maybe you would divide the port area in half? 1/2 for each driver? hmmm.... im lost. You could try calculating both ways and see how much they differ.

brokeitagain
11-18-2007, 08:22 PM
and where do i find this calc?

dan5505
11-18-2007, 08:23 PM
I think i know what your saying now though, the left driver wont be using the port area on the right side of the box and vice versa.

brokeitagain
11-18-2007, 08:28 PM
thats what i meant i know it is kinda difficult to understand what i mean until u think of how the port is arranged in the box

RAM_Designs
11-18-2007, 08:28 PM
http://www.carstereo.com/help/Articles.cfm?id=31

brokeitagain
11-18-2007, 08:34 PM
that isnt what i need to know, I WANT TO MEASURE THE BOX I AM LOOKING AT THAT I AM CONSIDERING BUYING, SO I KNOW THE TUNING FREQUENCY OF THIS BOX WILL BE WHAT I OR NOT

dan5505
11-18-2007, 08:37 PM
do you know the dimensions of the box?

brokeitagain
11-18-2007, 08:43 PM
out side dimensions are 13.5 high, 17.5 deep, 34 inches wide, its build from 3/4 MDF
The port in side dimentions are 3" wide 12" tall 14" deep

EDIT: driver displacement is .068

twisztdauthorit
11-18-2007, 08:45 PM
this thread is a failure.....
just use a **** calculator... theres nothing more accurate then one.

brokeitagain
11-18-2007, 08:49 PM
i would rather be able to do it with brains rather than be lazy and use some online calculator like so many lazy fvcks do.

dan5505
11-18-2007, 08:49 PM
out side dimensions are 13.5 high, 17.5 deep, 34 inches wide, its build from 3/4 MDF
The port in side dimentions are 3" wide 12" tall 14" deep

EDIT: driver displacement is .068

K, now calculate your net volume from that. You need to get the xmax value for the drivers. Put all that info into here. http://www.subwoofertools.com/forum/ported-box.asp
Adjust the tuning frequency until the correct total port area is found. Whatever that frequency is, is the frequency of the box with the drivers you chose.

mobeious
11-18-2007, 08:50 PM
all u do is take the total cubic feet of the box and the size of the port and plug that into winisd and it will give u a port length, and lets say ur port length is 30" long but ur box is only 20" deep... the port has to go the difference of that each way not the length cut in half and L off each way ... mmm hope that makes since

brokeitagain
11-18-2007, 08:51 PM
fk it iwill just build a ****** box that way i know it will be right

dan5505
11-18-2007, 09:02 PM
calculating it didnt work?

mobeious
11-18-2007, 09:07 PM
gimma the dimentions and ill do a draw up for ya

brokeitagain
11-18-2007, 09:09 PM
out side dimensions are 13.5 high, 17.5 deep, 34 inches wide, its build from 3/4 MDF
The port in side dimentions are 3" wide 12" tall 14" deep

EDIT: driver displacement is .068

mobeious
11-18-2007, 09:11 PM
how many subs what size
port in middle or side,,, subs up or foward,, port back or on same plane as sub

brokeitagain
11-18-2007, 09:12 PM
i want to know how to figure tuning for a box like pictured at the beginning of this thread.does anyone see how the port is ran in that box?

brokeitagain
11-18-2007, 09:13 PM
port and sub on same plane
2 subs

RAM_Designs
11-18-2007, 09:18 PM
i would rather be able to do it with brains rather than be lazy and use some online calculator like so many lazy fvcks do.

everyone uses calcs...you're officially a *******.

brokeitagain
11-18-2007, 09:25 PM
fvck u

mobeious
11-18-2007, 09:27 PM
http://i7.photobucket.com/albums/y290/mobeious/Untitled32434.jpg

brokeitagain
11-18-2007, 09:28 PM
this enclosure does not have the divider in the port

mobeious
11-18-2007, 09:32 PM
if u dont have the divider u are going to have to put a 45 deflector in there
the port is to to long to go that far back and not L off or have a divider

brokeitagain
11-18-2007, 09:34 PM
what i wanted to know is how to figure a port that does L off into the chambers on both sides,whit no divider

RAM_Designs
11-18-2007, 09:35 PM
this enclosure does not have the divider in the port

are you seriously still confused??? Both subs share the port, like in this box:
http://i45.photobucket.com/albums/f92/RyanM923/SB1_RE8/SB1_RE8001.jpg

As I said before, there's no secret to this. You can use one port for 1000 subs...the number of subs does not matter.

mobeious
11-18-2007, 09:37 PM
the length of the port goes both ways

RAM_Designs
11-18-2007, 09:37 PM
what i wanted to know is how to figure a port that does L off into the chambers on both sides,whit no divider

The part that branches off into each side will be one half the width of the original port. An easy way to think of it is "however long you would need to go past the back of the box, that's how far, from the center of the original port, that you need to branch off into each side."

brokeitagain
11-18-2007, 09:38 PM
******* **** is everybody blind cant u look at the pic i posted and see how the port is in there?

brokeitagain
11-18-2007, 09:39 PM
what about the volume of the box ?
is it one box or two?

RAM_Designs
11-18-2007, 09:42 PM
what about the volume of the box ?
is it one box or two?

Since air can flow easily from one side to the other, it'd be one box, shared chamber.

RAM_Designs
11-18-2007, 09:42 PM
******* **** is everybody blind cant u look at the pic i posted and see how the port is in there?


The part that branches off into each side will be one half the width of the original port. An easy way to think of it is "however long you would need to go past the back of the box, that's how far, from the center of the original port, that you need to branch off into each side."

now stfu.

mobeious
11-18-2007, 09:47 PM
here this should explain it this is if ur port board had to be 17.75 long, this is how u do it

http://i7.photobucket.com/albums/y290/mobeious/Untitled3243664.jpg

theo740IL
11-19-2007, 07:43 AM
you just want the math formula to figure it out yourself right? i was looking for the same thing a while back and couldn't find nothing!!! i kept finding all those different calculators (re audio calc, the subwoofer tools one, winisd, etc) but then i read a bunch of things in these forums and other places that those calculators aren't that accurate. so good look man i looked for a while!

jmrunz
11-19-2007, 10:54 AM
brokeitagain. dont get discourraged people just tell you what they know. with that here is what i know.
when you build a box for 2 subs shared space the volume needs to be big enough for both subs. say each sub requires 2 cubes then you need a 4 cub net box. keep in mind that that is after port and sub displacement. you can easuly end up with a 5.5 cube box to get 4 cubes net.
a rull of thumb we use is 16 inches squared per cubic foot of box volume. when you run a divider in the center of the port dividing the chambers up the playable area comes back into each chamber a bit.
port tuning is dependand on surface area and depth of port. the smaller the surface area the higher port noise you have. if you go to ddaudio.com and use their calculator it works real good but you want to figure it out yourself i have a couple of formulas and web sites you can visit to get these for yourself and i hope they help you as they have helped me a ton.
here they are.
http://www.realmofexcursion.com/forum/showpost.php?p=447126&postcount=1.
http://www.caraudio911.com/tutorials/PortedBox/images/001.gif
http://www.usenclosure.com/Enclosure%20Formula's/enclosure_formula.htm
and here are some difinations of abreviations
.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

again i hope these pages and info helps you in what you want.
james