Round Port tuning Help needed

[hookdupexpo]

Alright, im building my first box, and got all the measurements and think it should go pretty easy since my dad is good at all that handyman stuff. I know how to use the calculator to get the tuning thing, but i wanted to use two round ports to minimize port noise. So if it says for example 30 in long for a 4 in. pvc, then how long would it be if i wanted to use 2 4" PVC's? Also, is it worth it to spend like $12 each on those flared ports, or will it work alright if i just sand the edges on some pvc? Thanks for any help.

[hookdupexpo]

any help?

[HAVINGFUN]

Adding another port means you have to double the length basically, so you would need two 60 inch ports and that is why many use the slot ports. Depending on the sub you can easily get away with a single 4 inch port that is flared by a router or sandpaper or buy the flared one.

[AznRevlAzn]

search for georges box making. calculate from slotted area to cylindrical area. Bam.

[hookdupexpo]

thanks, i got it...