Can someone help me on measurements for a vented box???


i am building a vented box for my sub an i need to see if anyone can double check my measurements for me!!???

well here is what i have so far:

internal gross volume: 2.25 cu ft
tuning frequency: 34hz
vent opening size: 2"x12"
vent length: 27"
driver displacment: 0.075 cu ft
internal net volume: 1.79 cu ft

is there any way someone can check this for me???I need to know if this is right or anywhere close to being right!!!???

also can you give me info on building a vent that bends around a corner, i have to bend the vent and i know that the calculations are different from just a staight one...just dont know the math involved in bent vent....can you help me out here....

by the way i use an internet calculator to get these numbers....

here is the URL

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 1527
Registered: Dec-03
I think you meant 0.79cu ft for the driver displacement.. unless those are tweeters :-)

remember to add in displacement for the port(s) as well.

you can double and even triple fold teh vent if needed. it's fairly common to do so.

my sub is 0.075cu ft.....0.79cu ft is as big as the box my friend's 10 is


the volume of my box w/o the sub or vent is 2.25cu ft and 1.79cu ft with the sub and vent.

i know that vents can have bends in them, but how do i measure it???

my vent has to go down one wall of the box, hit the back of it and i just make the 27" measurement on the wall of the box or do i measure the wood that makes up the vent???

also is a 12"x2" vent that is 27" long in a 2.25cu ft box create the tuning im looking for???(34hz)???

one other thing....after i subtract the driver displacement, vent volume, and volume of wood used to make the vent i have 1.79cu ft left in my 2.25cu ft box....maybe this will help in some way.

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 1542
Registered: Dec-03
I'm used to displacement for subs like a W7. they're a bit larger. heh

don't bend the ports, just fold them.
like so:
TL enclosure

then just calculate for volume at the folds so the overall port size remains the same for both length and diameter (displacement)

1.79cu ft is your box volume then, and what you use to calculate port size.
remember, the ports are considered "external" and not a part of the box volume.
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