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chowdog
02-01-2012, 08:51 PM
trying to build a vented box for 4 12's in an extended cab chevy truck but need help figuring out my internal volume and how large my port needs to be. im wanting the subs to fire forward and the vents to fire up toward the ceiling. im using 1" mdf and already have all the measurements for the box figured out, i need to know how much air space each divider will take up and also how much each baffold will use for the vents. any help would be appreciated.

winkychevelle
02-01-2012, 08:55 PM
id go 7 cubes ported to around 32hz with 16sq inches of port per cube or (4) 4inch aeros

chowdog
02-01-2012, 09:06 PM
i need each chamber to be 1.5 volume and want retangle ports

chowdog
02-01-2012, 09:18 PM
anyone else have anything?

jeremyg1
02-01-2012, 09:19 PM
Are you building 4 separate enclosures or 1 enclosure and all of the drivers in there own chamber?

Max height, width, and depth?

Which subs?

chowdog
02-01-2012, 09:26 PM
one enclosure with seperate chambers.
max length of box 58"
im wanting to stay around 19" for the height
and 14" for the depth.
im using hifonics brutus 12's round ones

winkychevelle
02-01-2012, 09:30 PM
that box is gong to be too small for 12s tens would fit better

jeremyg1
02-01-2012, 09:32 PM
that box is gong to be too small for 12s tens would fit better

I agree, before any displacement is taken into account you are looking at 7.15 cubic feet, which is about enough room for 2 of these 12s after you take displacement of vent and everything else into account.

chowdog
02-01-2012, 09:32 PM
thats the box dimensions i ahve for the 12's now but the box is sealed and i want to go vented. these dimensions are not exact of what i have now but they are close. and my air space is dead on for what the subs call for.

jeremyg1
02-01-2012, 09:34 PM
thats the box dimensions i ahve for the 12's now but the box is sealed and i want to go vented. these dimensions are not exact of what i have now but they are close. and my air space is dead on for what the subs call for.

Per the manual you are correct, that is perfect for what they recommend in a sealed enclosure.

For a vented enclosure they recommend 12 cubic feet net for all 4 drivers.

chowdog
02-01-2012, 09:44 PM
ok 58 length 30 tall and 16 deep outside dimensions with 1" mdf is 12.7 now what?

duanebro
02-01-2012, 09:56 PM
ok 58 length 30 tall and 16 deep outside dimensions with 1" mdf is 12.7 now what?

find the inside dimensions, adding in three extra panels, or subtracting for them which ever makes more sense to you, then figure out the volume for one sub by dividing by 4.

duanebro
02-01-2012, 10:12 PM
then figure out the width you can make the port. There are several online calculators that can calculate port length, or I can if you post the volume or h x w x d.

You may find that the port is longer than you want. Since bigger boxes use shorter ports I may help to go with two subs per chamber.

jeremyg1
02-02-2012, 12:48 PM
Okay, here is what I have come up with, but please double check all of my math:

At 58 inches wide, all of out 1 inch MDF and a divider between all drivers, you would have 13.25 inches of width per speaker.

That said, in order to maintain ~3 cubic feet per driver after all displacement is taken into account you will need a height of 38 inches.

This accounts for the displacement of the port which will be 13.25 x 3 x 20 (12.78 sq inches of port per cubic feet...a bit on the small side but I am sure it will work.) at a tuning of 35Hz.

If someone could double check this I would appreciate it.

What I would recommend, if that height is a concern. is going against the idea of individual chambers and going with one common chamber, this will reduce a lot of the displacement.

pro-rabbit
02-02-2012, 12:53 PM
Why 1" wood? It won't save you much, but utilizing bracing and 3/4" wood will net more volume. Not much, but in this case every little bit helps.

Also, depending on your amp setup I would just do a large common chamber enclosure. This will allow you to skimp a little on volume if you absolutely have to, all though I don't really suggest it.

Using a common chamber enclosure, with 3/4" mdf, proper bracing, and a single port you will find this to be much easier to fit.