[The Chief (tm)]

Same here.

In my case it sounds like it comes only from the driver's side. Also, it doesn't happen on every bump or road imperfection, which sorta makes it more noticeable when it does! (Not to mention that, if driven calmly, the car is very solid and quiet indeed, with the top up.)

If it matters, I am almost positive that it does NOT happen when the top is lowered.

I, too, will probably not try to diagnose it, because I can't think of any good way to check on anything unless the top is lowered, partially or fully, and then that's when the sound disappears.

If you discover something though, by all means post it, and maybe within the "Convertibles" sub-forum.