[Mike P.]

12 cu.ft tuned to 16 hz works well, I have two IXL-18's in that setup. A box with external dimensions of 22" x 22" x 55" would fit in the corner nicely. If you want to down fire the sub then add 4 or 5 inches for legs and the thickness of a base plate. The sub will handle 850 watts with a HPF at 14 hz. The cheapest way to tune would be a 8 inch sonotube 34.75" long.

 

[Mike P.]

Side firing is fine.

Post #38 in this thread shows an example of excellent bracing.

http://www.hometheatershack.com/for...6301-mach-5-ixl-18-2-2-build-358l-15hz-2.html

As for WinISD, if you're using Vista there are known issues with the program.

 

[Mike P.]

You can download the WinISD file here:

http://www.hometheatershack.com/forums/diy-subwoofers/14410-downloadable-winisd-pro-files.html

 

[Mike P.]

Uninstall all WinISD versions you have on your computer. Reinstall WinISD Pro, as that's the only version the above files will work with.

 

[Mike P.]

The default end cap thickness is 2.25 inches. Most people use 1.5 inches which is double 3/4 MDF. Change the end cap thickness to 1.5 inches before you enter any other info into the program.

If you build a sonotube, there is a release film on the inside of the tube that glue won't stick to. You'll have to peel it off before attempting to glue the end caps to the tube.

 

[Mike P.]

Two 6 inch diameter ports would need to be 45 inches long each to tune 12 cu.ft. to 16 hz. They would displace 1.5 cu.ft. so you'll have to figure that into your box calculations.

 

[Mike P.]

The volume that you enter into WinISD is the net volume of the cabinet, which is the effective amount of volume that the sub "sees". You have to add the displacement of the sub, ports and bracing to the net volume to get the total internal volume.