Nice job Dan. Years ago, I had a friend who worked management in the construction business. When building bridges, the newly formed steel beams would be constantly "pinged" until the stresses were relieved (and checking for hairline cracks etc). They measured (more accurate than listening) the resonance(s), and harmonics, to determine when the process was complete. This generally took about a month to accomplish, which seems to follow what, from what I have heard, metallic cones need to "breakin", let alone the spider, surround material etc.
Decades ago, Chrysler used to let their engine blocks set for up to a year to allow for stress relief.
Good work Dan.
