I was wondering what length port tube you used in your design. We purchased the adjustable one but were wondering if you could suggest a starting point. I have made some deviations from your design as per the professor I work for requests. First we did not get the curved back speaker boxes, due to a miscommunication, but we are still using your design as a base. We are also testing the output at different stages so all I have added so far is the speakers and the port tubes.