HELP - Port Length for new Sonosub????

[Newfiestang50]

Guys, I need help with my port length, I am about 75% complete with my sonosub but I am questioning my calculated port dimentions 6" x 25" (using 6" sonotube which has a OD= 5 5/8" and ID= 5 3/8") in unibox, it just seems a little short from what I can remember reading on other designs here. I was kind of expecting around a 30" long port for 15hz, does the 25" seem right??

My design consists 250L and I was aiming for a 15Hz tune using a RL-p15 D2

[WillyD]

In unibox, using that ID, 24.6" gives me a ~15.5Hz tuning.

[nick77]

I have an RLP-15 also and with 260L and 28" port at 6" for a ~16.7 tune. It was reccomended that the lenght be 28-30" on the port.

[Dennis H]

I think the other designs you've seen are for a true 6" ID so your smaller diameter tube will also need to be shorter for the same tuning. In WinISD Pro, just using the defaults for everything, I get 15.4 Hz with a 25" tube and 15 Hz with a 26.7" tube.

[Jerm357]

I also come up with 26.8" for a 15hz tune.

[Newfiestang50]

I also come up with 26.8" for a 15hz tune.

Ok thanks, I will try 27", it should be ok I guess for 15.5 hz.

[WillyD]

I think the other designs you've seen are for a true 6" ID so your smaller diameter tube will also need to be shorter for the same tuning. In WinISD Pro, just using the defaults for everything, I get 15.4 Hz with a 25" tube and 15 Hz with a 26.7" tube.

Yeah, I dunno what I did the other night, but I got the same (26.7") for a 15Hz tuning.