Questions on Box Design (port volume calculation)

[whizdumb]

Hi,

Well I should be getting my 15" "TC9" from DaGh0st here shortly (one of the ones teamquakecelica is selling) and I'm trying to design my first box.

I think I have everything pretty much figured out except how to calculate the net box volume (by subtracting the port volume)

I know in order to figure out the port length needed, you have to use this formula,


then factor in end correction by subtracting 1/2 the width of the port from the length...


My question is, for calculating the port volume do you use the physical volume (between the port walls), or the effective port volume (using the end corrected lengths)??



And another question... say my front baffle is 16.5" x 16.5" and the basket diameter of my sub is 15.65", is that enough room for it? how much "meat" do you need around the outside of the sub to screw it in and have the wood be strong enough??

Thanks!!!

[Kold_Killa]

For that 24" port... it is roughly

4.75*H*24 = V divide V by 1728 to get cuft

Without the height of the port I can't tell you the volume it takes up...

the 4.75 is the port width, plus the width of mdf (3/4 inch)

[whizdumb]

Oh yeah, I forgot to mention -- those aren't my pics. Special thanks to caraudiojunkyard for those!

Thanks Kold Killa, so you do use the "end corrected" size for the volume. Good to know... never was sure about that before.



One more question (sorry i'm a n00b):
Do 45 degree braces in the corners help more for SQ or for SPL? Seems like they would help for both but according to teamtoxicbass's tutorials they can actually hurt SPL?

Reason I ask is I am going to have one box for daily/sql and one for SPL just for fun...

[Trixter]

first off, i like my formula much better (see sig)

for the port's volume you need to measure it's H, W, and L. the H will be whatever the box's internal H is. the L will be the port's total length, including the correction, but subtract 3/4" for the front baffle. the W will be however wide it is plus the 3/4" for the inner port wall.

if you make you front baffle the entire H and L of the, not set inside on the sides and top, you'll be fine.

the 45deg pieces can make the box more ridgid, help direct air flow and help prevent standing waves. all of this help both sq and spl.

[danteBirosel]

Oh yeah, I forgot to mention -- those aren't my pics. Special thanks to caraudiojunkyard for those!

Thanks Kold Killa, so you do use the "end corrected" size for the volume. Good to know... never was sure about that before.



One more question (sorry i'm a n00b):
Do 45 degree braces in the corners help more for SQ or for SPL? Seems like they would help for both but according to teamtoxicbass's tutorials they can actually hurt SPL?

Reason I ask is I am going to have one box for daily/sql and one for SPL just for fun...

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