I used WinISD to calculate the length of the port tube for some speaker cabinets I am refitting. Depending on how the information is entered, I arrive at two port tube lengths within a 1/4" of each other. Something like 44 and 51 cm - should I split the difference.

Stats: 2 ports, 3 7/8" diameter
Volume: aprox. 7.5' (width 20.5", height 47", length 14.5")
Delta Pro - 15" drivers
3/4 Birch Cabinets

Tweeter: PSD2002
Thanks in advance
Jim