Hi Robert,
I’s been a while since we’ve made contact. Things are going well. The
Ultimate series uses a 3″ diameter steel tube except for the smaller
U-545 which uses a 2″ diameter tube. In both cases, the thickness of
the tube is about 1/8″. The tubes, as you would expect, are quite
massive and have a mass resonance far below human perception. The tube
is normally empty and is capped on both ends such that an acoustic wave
cannot enter and resonate. We have some owners that have filled the
tube with sand or other material to eliminate cavity resonance, but this is not necessary. Even at the highest audio levels the acoustic energy isn’t sufficient to penetrate the tubes and filling them makes no difference. I hope that this adequately answers your question.
Hope all is well with you.
Best regards,
Roger
Sound Lab, Inc.