I assumed that this was the interviewers observation and not a fact, because even a mid-range driver would be moving visibly. Considering the size of the tube,

I assumed that this was the interviewers observation and not a fact, because even a mid-range driver would be moving visibly. Considering the size of the tube, this is certainly not a driver big enough to go to lower frequencies. (Specialized drivers at 4" can go down to 25hz though)