going by filter theory a jammed BW would be ~4.1cu.ft and tuned to 47Hz with f3 of 47 and Be4 of same volume tuned to ~38hz with f3 of about 58hz - did you simulate for boxes in ~4-5cu.ft. range tuned about 1/3-1/2 octave above 30hz? - one guy says a Karlson's front chamber air mass will effectively shift qes upwards and fs downwards allowing a different response to be achieved than with regular VB

Freddy