Thanx guys for your help. Unfortunately HO 18 went out of stock and wont be available till mid April next month. So, my project is delayed for a bit. However, I need some clarification on air velocity. I modelled HO 18 in 10 cu ft box with 900 watts input power and tuned to 19Hz. The port velocity is having me pull my hair. My objective is to avoid bends in the port and keep it short.
Yellow is port velocity with 8 3/8" size port. Sorry but the colours are not showing correctly in the attached graph.
The PVC pipes we have here are slightly bigger and are rounded off to the lower values, hence the extra 3/8" dia. Anyway keeping every other thing constant and with 8 3/8" port size, I get roughly 34" long port. And if I reduce the dia to 4 3/4", I have to deal with 3 ports of roughly 30 inches lenghts to keep the port velocity below 8% of air speed.
Will going by one 8 3/8" port be better than using three 4 3/8" ports? It will be easier to control the gross box volume with one large port than to account for the extra air volume occupied by three ports for the final box volume that includes bracing also.
One more thing.....By what percentage does falring reduce port velocity?? I mean WinISD doesn't simulate the effects of flaring on the velocity. Is there any program/software that can show this??
I hope I have clearly explained. Any help is appreciated, thanx