View Full Version : atomic apx 18"

01-18-2007, 11:44 PM
im lookn to build a box for an atomic apx 18 heres roughly the the dimentions in this photo i just dont know how big to make the port tryin have it tuned to 32-40 hz

01-19-2007, 12:16 AM
are you wanting to know how much port area you should have, or how long the port should be, or all of the above

01-19-2007, 12:24 AM

01-19-2007, 09:13 AM
This would be highly dependant on how you want the box layed out and what type of port do you want to use.

To give you an example, based on the outside values you gave. If you want a slot ported box with the port on the same face as the sub, you would have the following:

Net Volume: 7.60 cu/ft
Tuning Freq: 40.00 Hz
Slot Vent Width: 3.00 inches
Slot Vent Lenght: 11.00 inches
Port Volume: 85.50 sq/in


Net Volume: 6.70 cu/ft
Tuning Freq: 32.00 Hz
Slot Vent Width: 3.00 inches
Slot Vent Lenght: 26.00 inches
Port Volume: 85.50 sq/in

Now this will be completely different if you want the port on the 15" panel or with round ports.

01-19-2007, 09:47 AM
With that sub your gonna want close to if not more that 100sq" of port.

01-19-2007, 10:39 AM
I usually base the port area on the net volume of the box, to give people an idea of what they are looking at.

JFYI, if you wnat more port area you will drastically effect the amount of net volume your driver see.

01-19-2007, 01:28 PM

well i was looking to build the box like this but for one single 18" sub

01-19-2007, 04:59 PM
looks just like one I designed for 2 12s

and another for 12 15s


01-19-2007, 06:15 PM
http://img263.imageshack.us/img263/4316/18atomicapxlz6.png (http://imageshack.us)

port is 6"x19"=114^2" of port area. and it is 20" long tuning it to 35 hz
. after port displacement, it is 7 cubes

exterior dimensions are 36x36x14.75..im not sure that you would need a double baffle or not, probably better going with one though