I know with mids and woofers and subwoofers you need to get the spider and surround loosened up but since a tweeter does not move much do you still need to break them in?

 

Break-in has at least as much to do with you becoming accustomed to the new speakers, as it does with physical changes. Loudspeakers vary more from unit to unit for most T/S parameters, than they vary from beginning to end of a break-in period. Go with the manufacturer's specifications when designing crossover and enclosure parts, unless the manufacturer's specs are notoriously wrong - in which case, use a different manufacturer!



A couple of well-phrased searches on Google yield



comments from an expert on tweeter break-in (designers take break-in into account)

actual measurements, albiet not for a tweeter, showing the wide sample variation you might find, and this from a good name (Audax)



ETA: also this: http://matrixhifi.com/ENG_contenedor...ealtavoces.htm

 

I broke all my speakers and subs in by playing them low to medium for about a week to break them in. After that I let them loose and started blaring them and they have been great. That was over a year ago.