port length question

[Jester1318 10+ year member]

For those of you familiar with bass box pro and/or winisd, help me out here.

The box is 2 cuft tuned to 30hz (12" rlp), 4" precision port

When I do this calculation (Lv=((8466.4*r^2)/(Vb*Fb^2))-(1.463*r) I get a number like 15.89". Winisd gives 16.28" with end correction being .614 (is that right for 2 flared ends?) And Bass box Pro gives a length of 17.35".

Which of these is correct? Or is there some other part if it I am missing? It seems as though they should all be the same length if my numbers are identical, but they obviously are not.

Also, a precision port ordered from PE is 17" in length with adding the flares and not cutting anything, correct?

Thanks

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[PhatTonyDeMarco 5,000+ posts]

I dont know which is correct, but you wont hear an audible difference between the two lengths...

 

[Beat_Dominator 5,000+ posts]

Your first one is correct, BBP and WinISD are a little off and they won't fix it.