[How To] Design a ported box

[seth350 10+ year member]

Now for the other part of my write up....

Slot Ported Boxes

Ported boxes are similar to sealed boxes in the way you calculate the airspace.

You still start out finding out how much cuft you need and then going from there.

Lets begin.....

Lets say your sub needs 3.5cuft ported and you want it ported at 33hz.

You first begin by finding what measurments will give you 3.5cuft.

To calculate for cuft, read my other article for instructions on how to do it.

http://forums.caraudio.com/vb/showthread.php?t=128157

WxHxD

34"x18"x13" = 3.56cuft Close enough!

Ok you have your dimensions, and your net volume now time for the port.

I recommend using a program like WinISD for this. Its quick and easy to do.

Punch in the parameters and we get this....

WxHxL

3"x18"x30.5" = 33.66hz

Now you have decided on how big of a port you want. Now its time to calculate its displacment.

#1 What you do is you take the length (30.5") and substract .75 from it. = 29.75

#2 Then you multiply that by your height (29.75x18=535.5)

#3 Then take your width (3") and add .75 it (3.75) then multiply by what you got in step #2.(535.5x3.75=2008.125)

#4 Now take the number you got from #3 and divide it by 1,728 (2008.125/1,728=1.162109375) then do significant figures and you get 1.16cuft.

Now you have your port displacment and now you need your sub disp.

Lets say your sub needs .18cuft displacment.

Ok now here is what you do.

Take you net volume (3.56cuft) and add your port disp. (1.16cuft) and add your sub disp. (.18cuft) together and you get your gross volume which is 4.90cuft.

Now, you have to make adjustments to your dimensions in order to get 3.56cuft after you add the port and sub.

So now you take the measurments you started out with and adjust the height and width until you get 4.90cuft.

Which you should end up with 36.75"x18"x16" and that gives you 4.88053cuft and then do significant figures and you get 4.90cuft.

You dont change the height b/c then it would mess with the disp of the port and also cause it to change the tuning and it gets confusing from there. So do not change the height when adjusting your measurments

Now you build the box to those dimensions, not the dimensions you started out with.

You use the new measurments because then when you put in the port and the sub you have 3.56cuft left for the sub. Which is what it called for!

Now you have designed your own box and its done right! Hopefully........

Hope this helped out the noobs, and anyone else who needed it.

Click to read more...

 

[danteBirosel 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/bowdown.gif.b85b23b82970bd22fb6b549c3392f016.gif :bowdown: //content.invisioncic.com/y282845/emoticons/bowdown.gif.b85b23b82970bd22fb6b549c3392f016.gif

great mini tutorial!

 

[XtrmAudioCncpts 10+ year member]

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

 

[seth350 10+ year member]

Yeah but mine is more simplified I think and not as intimidating to noobs as that one is.

Oh well, guess it was all a waste then.

 

[PepsiFiend69 10+ year member]

what happens say if you're making a 1 chambered box for 2 subs, with 1 port, does the port stay the same size, or does it need to be doubled?

 

[bimma85 5,000+ posts]

Yeah but mine is more simplified I think and not as intimidating to noobs as that one is.
Oh well, guess it was all a waste then.

but this may help all the noobs to lazy to search lol, at least for a few minutes //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[seth350 10+ year member]

what happens say if you're making a 1 chambered box for 2 subs, with 1 port, does the port stay the same size, or does it need to be doubled?

Your port wont change, however you will need to compensate for both of the subs displacment.

So when getting your gross volume, add your net volume and your port displacement and both of your subs displacment and you will get your gross volume.

That volume is how much you need in order to have the needed amount for both of the subs.

You then would adjust your width and depth until you get that amount. Then build to those measurments.

 

[PepsiFiend69 10+ year member]

thanks!

 

[seth350 10+ year member]

but this may help all the noobs to lazy to search lol, at least for a few minutes //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Unless a mod stickys it......which is what Im hoping.

Make it really easy then for all of us.

 

[seth350 10+ year member]

thanks!

Anytime //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[PowerNaudio 10+ year member]

seth350: thats a great way to explain displacements and enclosure calculations

but you should add how to fold a slotport.

could you explain it to this image in on you own words. plz

http://tinypic.com/hvcdac.jpg

 

[seth350 10+ year member]

Thats a really good diagram. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Basically, you can't get your port length by cutting port two walls and having their lengths equalling 40" long.

Instead you have to find the center point of the port and measure out 40" from the front to the center point and from the center point to the end.

Then you build your walls accordingly.

The diagram gives a great example on how to do that. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Omarvelous 10+ year member]

I don't think it was a waste, bu i do think atleast 1 of these threads should be given STICKY status

 

[PowerNaudio 10+ year member]

Thats a really good diagram. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
Basically, you can't get your port length by cutting port two walls and having their lengths equalling 40" long.

Instead you have to find the center point of the port and measure out 40" from the front to the center point and from the center point to the end.

Then you build your walls accordingly.

The diagram gives a great example on how to do that. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

thanks for the compliment on the drawing, i tried to cover what you where explaining and added a little using a drawing.

yeah we need a sticky on how to do all the calculations for a ported enclosure.

that way the same questions wont get asked over and over.

 

[PowerNaudio 10+ year member]

i try lol