# Ported Box Design Questions



## audioanarchist (May 20, 2010)

I searched for these answers and couldn't really find them or if they were there I didn't understand terminology so I might need you guys to dumb some stuff down for me.

Does WinISD *estimate* how much air space a sub of a given size takes up inside the box?


Does the *PSP* calulator *assume* the port is inside the box or outside the box?


Does the *WinISD* *assume* the port is inside the box or outside the box?


I plan on using a *single* DC Lvl3 *10" Subwoofer* in a 1.7 cuft box with a 3 inch internal port 11 inches long. It has an *Xmax of 23mm*. Is a 3 inch diameter port big enough for a 10" sub with that much excursion? If I go with a 4" port my box is gonna be tuned to a higher then desired frequency because I can't make the port as long as it needs to be or i might have to have the port stick out of the box a ways(that'd prolly bug me). *So yeah is a 3" port gonna be big enough for this application?*


Guess-timating the air space the port and speaker take up:
3" port 11 inches long = .05 cuft?
DC Lvl 3 10" subwoofer = .05 cuft?
The two of Combined = .1 cuft
Knocking my internal volume from 1.7 cuft down to 1.6 cuft?


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## azngotskills (Feb 24, 2006)

WinISD does not account for driver or port displacement....its NET volume


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## Austin (Mar 12, 2009)

audioanarchist said:


> I searched for these answers and couldn't really find them or if they were there I didn't understand terminology so I might need you guys to dumb some stuff down for me.
> 
> Does WinISD *estimate* how much air space a sub of a given size takes up inside the box?
> 
> ...


Underlined answers



> Guess-timating the air space the port and speaker take up:
> 3" port 11 inches long = .05 cuft?
> DC Lvl 3 10" subwoofer = .05 cuft?
> The two of Combined = .1 cuft
> Knocking my internal volume from 1.7 cuft down to 1.6 cuft?


I would say:
3" port 11 inches long = .061 cu ft (I'm assuming you are using pvc pipe which is typically .25" thick. So i added that to the diameter which = 3.5")
dc Lvl 10" sub= .10 cu ft
combined: .161 cu ft (or .16 if you want to make it easy)

If you made you box with a tuning you like and it came to 1.7 then you would add the volume of these two which would be:
1.861 cu ft total.

When i use winisd to design a box and then have it calculate the size i need it to be then i add the approximate volume of the sub (10" usually .1 and 12" usually .15) then add the volume of the port and add all that to the main volume needed for the sub. Then go to box calculator and figure out the size. But make sure you look at the box graph and response before you make the volume bigger.


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## audioanarchist (May 20, 2010)

Sweet thanks Austin that clears alot up for me.

Oh yeah and the psp calculator is this thingy:

Products Menu


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