Dukk I was trying to use kicker's specs on their 2.5 cubic foot box for the 12l7, and I used their Av, Vb and Lv values and plugged it into this equation:

http://www.jlaudio.com/tutorials/ports/images/Fb.gif

Now I have done engineering algebra at a university level, and so computing was not difficult....but I was unable to compute the Fb that kicker stated...the value I computed was much lower than their stated value. Their Vb #'s are always ususally stated as a net value, correct?

Thanks a LOT for those calculators...I think I am just going to use them instead of computing it manually (saves a lot of time and eliminates any quick errors).

Dukk, that 2nd calculator you provided has the option of choosing a "slot port" as an option. Is that what I am making here (the sides of the vent will be created by the enclosure wall except for one side)

ALSO, Do you guys factor in the "end correction factor" ? Is that "end correction factor" only used with vents that are not straight and have bends/corners in them?

^not Dukk here, not even close; but yes if one of the enclosure walls is part of the port, its a slot port.
There's a correction factor applied, about 1/2" added or subtracted (I forget right now, I think sub) in the calcs.

*edit* I think that's the correction factor I mentioned above^.

When you turn corners for the port, you measure your port length in the middle of the port, turn the corner in the middle of the 'around the corner' port, and continue measuring.

I hope that makes sense; and wait for confirmation on that "end factor correction". *edit*

Gene

[ August 28, 2004, 11:22 AM: Message edited by: Fever ]

Kicker takes into account driver displacement but not port displacement ...

However, if you look in the technical manual and scroll down to page 25, there are enclosure plans for the S12L7 ...

I have no idea how Kicker measures their boxes [img]graemlins/dunno.gif[/img]

End correction for a slot vent is to shorten the vent by half the width of it. So if the slot is 2" wide you would shorten the length by one inch. Incidentally, it wouldn't be audible either way. ;)

Ok so when creating a slot port, do I create the inner wall of the slot port (the wall which isn't part of the outer enclosure) exactly equal to Lv(eff)?

Sorry about all the newbie port questions

You measure down the middle of the port ... So the inner wall will be shorter than the length ...

Are you making an L-Shaped port ?

Yes I am making an L-shaped port.

Ok so the inner wall will be shorter by 1/2 lf the width of the port.

Port wall 1 = Internal depth - Port width
Port wall 2 = Total port length - External depth

http://www.soundsolutionsaudio.com/f...1093205548.jpg

Example :

Port length = 50"
External depth = 20"
Internal depth = 18.5"
Port width = 3"

Port wall 1 = 18.5" - 3" = 15.5"
Port wall 2 = 50" - 20" = 30"

This will give you a length of 50" measuring down the center of the port.

Port displacement (in cubic inches) = (Port wall 2 length x Internal height x Port width) + (Internal depth x Internal height x Port width)

More info

[ August 29, 2004, 11:09 AM: Message edited by: Jmac ]