2245H box/vent help

[elshout]

I am about to build a box for a 2245H sub. I am using the 1983 article: http://www.lansingheritage.org/html/.../1983-subs.htm

I am going to build the 12 cu ft - 25 hz unassisted box. If I read the article right, the port will be 9 inches? Is this correct? If it is correct it will be 20 inches in lenght.

I am not able to find any 9 inch PVC. I can find 6 inch, so can anyone tell me what the equivilant for a 9 inch x 20 inch port be if I use 2 - 6 inch ports? What would be the length of each of the 6 inch ports?

Any reliable help would be greatly appreciated.

Thanks
Scott

[loach71]

I am about to build a box for a 2245H sub. I am using the 1983 article: http://www.lansingheritage.org/html/.../1983-subs.htm

I am going to build the 12 cu ft - 25 hz unassisted box. If I read the article right, the port will be 9 inches? Is this correct? If it is correct it will be 20 inches in lenght.

I am not able to find any 9 inch PVC. I can find 6 inch, so can anyone tell me what the equivilant for a 9 inch x 20 inch port be if I use 2 - 6 inch ports? What would be the length of each of the 6 inch ports?

Any reliable help would be greatly appreciated.

You can get some "concrete form" (Sonotube) tubing at your building supply store. It is available in the size you need. The PVC tube - if available would be horribly expensive.

[grumpy]

reliable help? I get 12ft3/23Hz w/ 9"dia x 20" long port, using WinISD....
two 6" ports is nearly the same (19.25" each), just using plain, non-flared tubes
(slightly smaller cross area using 2 - 6" ports).

[johnaec]

You could also make square or rectangular ports. A 9" diameter circular port is 63.62 square inches, while an 8" square port is almost equal to that at 64 square inches.

John

[just4kinks]

This link is for car-audio, but the equation is the same and the information is very useful.

http://mobile.jlaudio.com/support_pages.php?page_id=165

[elshout]

Thanks for the responses. You all answered my questions perfectly. Sorry Grumpy, I did not mean to be offensive, I just did not want anyone guessing. I wanted an educated answer because I am new at this. You all gave some excellent advice.

Thanks again.
Scott