how do you determine tuning frequency?

[lee 2]

I know how to get port area in square inches, but how do I find out the port length and tuned frequency? I need to know the math to aquire my goals. cant find anything on this specifically, only port area which i already know

[QuestionMan 0]

Thats the tuning equation, if that's what you're looking for. To know the variables and how to use them, just go to jls website, it explains it pretty well. This is what i used to determine my tuning, as i really didn't trust the online calculators.

http://mobile.jlaudio.com/support_pages.php?page_id=165

[audio-neon 34]

Solving For Length of Vent or Port

Note

k values:

vent has one free end and one flanged = 0.732

vent has two free ends = 0.614

vent has two flanged ends = 0.850

Where

Lv = length of port or vent

Dv = diameter of port or vent

Dmin = minimum diameter of port or vent

Np = number of ports or vents

Vb = volume of box

fb or Fb = tuning frequency

k = end correction factor

Sd = surface area of subwoofer

Vd = driver displacement volume

Xmax = maximum linear displacement of driver

[audio-neon 34]

http://www.ajdesigner.com/phpvent/subwoofe...on_length_l.php

[helotaxi 46]

Important to note that "flanged" and "flared" are not even remotely the same. Flanged means that the end of the port is flush with a flat surface like an outside face of the box, whereas a free end is just the port sticking out into space like the open end of a PVC port inside a box withnothing around it. Flared means that there is a flare (like the bell on a trumpet) on one or both ends of the port. There are equations for that as well and they are somewhere in this forum. I built a fairly simple Excel spreadsheet for flared port calcs that DevilDriver hosted somewhere. Again there should be a link in that thread.

[audio-neon 34]

Important to note that "flanged" and "flared" are not even remotely the same. Flanged means that the end of the port is flush with a flat surface like an outside face of the box, whereas a free end is just the port sticking out into space like the open end of a PVC port inside a box withnothing around it. Flared means that there is a flare (like the bell on a trumpet) on one or both ends of the port. There are equations for that as well and they are somewhere in this forum. I built a fairly simple Excel spreadsheet for flared port calcs that DevilDriver hosted somewhere. Again there should be a link in that thread.

IF you find that link please post it, I can add it to my bookmarks.

[y_d0c 0]

Important to note that "flanged" and "flared" are not even remotely the same. Flanged means that the end of the port is flush with a flat surface like an outside face of the box, whereas a free end is just the port sticking out into space like the open end of a PVC port inside a box withnothing around it. Flared means that there is a flare (like the bell on a trumpet) on one or both ends of the port. There are equations for that as well and they are somewhere in this forum. I built a fairly simple Excel spreadsheet for flared port calcs that DevilDriver hosted somewhere. Again there should be a link in that thread.

IF you find that link please post it, I can add it to my bookmarks.

http://www.soundground.ca/index/flared_port_calc.xls

there it is...

[helotaxi 46]

That's the one. Nothing pretty but it works.

[filtor1 13]

So if Dv = the diameter of the port or vent, how would you measure this given a square port? Sorry if this additional question is redundant.

[aznboi3644 2]

convert from a rectangle port to a circle port with equivalent area

[filtor1 13]

convert from a rectangle port to a circle port with equivalent area

Thank you sir! I think I have got it.