maggi kuch sahi khabar rakha karo
i tune my box , according to that
where i get maximum DB SPL on 43hz
any lenght X of pipe dia 3.5" on which i get maximum SPL at 43hz will be the port of the enclosure
this is my concept
another thing playing below tunning frequnecy is dangerous for subwoofer
if played 33hz on 38HZ tunned enclosure ,
woofer will have to survive