I should have elaborated. unless the sound is obviously mechanical (in this case no) it is usually vibration caused by certain notes or excursion. Tightening the driver fixes this up.
Fixes tweeters too. I always tighten up speaker screws before I dial things in. The screw gun at Axiom is probably air driven and varies through production. I always get a full turn or more before they are truly tight. Sometimes more.
All manufacturers are likely the same. Even expansion and contraction of MDF can cause slack on the fasteners. Anyway, it works.
#1 Cause of speaker distortion. Amir never seems to mention that....
