Help with Sono port tuning please....

[mcallister]

I have a sono build that uses an Avalanche 18. The sonotube is 30" diameter and from bottom end cap to top endcap measures 54.5". The Length across the endcaps is 32".

Now I had my brother in law build this as I am terrible at DIY with no skills. So as of now I believe it's tuned to 16Hz. I'm wanting to lower the tuning to around 11Hz to 14Hz with the flattest response.

Forgot to mention I am using an 8 inch port (sonotube as well). The port now is 20".

What lower tune can I go to and still have a good response curve?


Thanks for any help!!!

[Mike P.]

Steve Callas has an Avalanche 18 in 23 cu.ft tuned to 13 hz.

http://www.hometheatershack.com/forums/diy-subwoofers-sealed-ported/12542-completed-llt-2-a.html

Your net volume is about 20 cu.ft. Tuning it to 13 hz would require an 8 inch port 34 inches long.