[fulafel]

The article mentions on one hand a high pitched note, but on another hand enough bass to see the subwoofers play it:

"Standing in the room, based on your sense of hearing alone, you’d never know that the loudspeaker was blasting an irritatingly high-pitched note. If, however, you peered into the PVC pipe, you would see the loudspeaker’s subwoofers thrumming away."

[tmikaeld]

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)