I used/have no software. Simply asked myself what line Fq would fit in a 36" x 30" box. 103" = 33 Hz. Reading others who can and have instruments to measure test enclosures reported a drop in Fq of 5 - 7 Hz when properly stuffed. Thus, I expect the line will drop to around 27 - 26 Hz... close enough for me to the Fs of 25 Hz. Thus the detailed drawing in case someone could "test" this in whatever commercial software they have.