factoring in port displacement

[dmz2711 10+ year member]

How do you go about factoring in the displacement if your port into your box volume when finding tuning frequency, if you don't know how long the port is till after you find the tuning frequency....which you can't find till you know your box volume......which you can't find till you know your tuning frequency so you can determine port length and thus volume LOL. Please help I must be overlooking something stupid. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

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[Immacomputer 10+ year member]

It's a number crunching and estimating game. If you know the max dimensions you can fit, start with that gross number and then subtract sub displacement. If you know the desired volume for the enclosure, enter that first and get a port length using your desired port area. Then calculate the port displacement and subtract it from your gross number you found earlier. If this is not equal to your desired volume, try adding a little bit more port area. If that doesn't cut it, shrink down a dimension or two.

That's how I have always done it. Just play with the numbers until you get something you like.

 

[nVRuckus 5,000+ posts]

yup if your first measurement of the port is 3 x 10 x 10 then take that displacement and take it from the total size of the box. this will make the port x amout longer then measure the displacement of the difference (i.e. is it becomes 13" long then you take displacement of the 3 x 10 x 3 difference)and take that from the box and so on. eventually you will come down to a difference of such a small number it wont matter.

 

[dmz2711 10+ year member]

so, by process of elimination from both the length and port displacement you narrow it down to the exact vb that you are lookin for. ok got it. thanks for the help!!!//content.invisioncic.com/y282845/emoticons/veryhappy.gif.fec4fed33b4a1279cf10bdd45a039dae.gif