However I have received some elsewhere. It was concluded that a closed tube would be best. Opening the tube at the back would accentuate the the pressure node right where the port is.

Making the port bigger would simply turn it into a transmission line speaker, and then 23 inches would prably not be long enough.

However I am planning on testing a model with an open back stuffed very tightly with fiberglas, and comparing it to one with a closed back stuffed tightly with fiberglass.

eric j.