Help with Aero port for 2 10 inch sub

[Bajan 246 0]

I have two 10 inch subwoofer in a very big box. 4.4 cubic feet before displacement. I have one 4 inch Aero I made with pvc pipe but I get noise at low notes,tuning right now is 30hz. Was thinking to go with 6 inch tuned to 33hz.

[Aaron Clinton 2,372]

Why in test section?

[///M5 2,833]

There were two of the same topic Aaron so I moved one here and locked it.