Do you think driver “break in” is real?

Do you think “high end” drivers and crossovers typically need a “break in” period before they sound their best?  I ask because, I believe I’ve experienced this first hand in a very significant way. I replaced the tweeters (same exact brand and model as original) in my ACI Sapphire 25 year anniversary edition speakers and for the first week I thought I’d lost my all time favorite speakers. I was depressed!  So I just kept playing them…  finally after a couple weeks, I’m literally stunned and blown away at how incredible these speakers sound. Completely different than the first 30 or 40 hours after I put in the new Scan Speak tweeters. So I say break in period must be real - at least for some drivers. Has anyone else experienced this to a degree that is unmistakeable?  
Crossovers too?  I just rebuilt the crossovers for a pair of ACI Sapphire XL’s (using highest quality components- same values) and so far they sound mediocre. Hoping for the same result as my other Sapphires but after about 20 hours - no noticeable difference - and they do not even sound as good as prior to crossover rebuild. They sound flat, too bright with poor imaging - but for 10 to 15 years they were pretty great sounding speakers. Thoughts on crossover break in?? 
Thanks to anyone who responds!!  


Several components to break-in. One is strictly post-manufacture time - like Magnepan glue which holds film to frame. That's a matter of time, not use, according to the factory. The same would hold for ESL's.

Then there's mechanical change as parts wear into a tighter or looser fit. And then there's warm-up, which matters in every listening session. My Quads sound better after a day's warm-up. My Class A  SS monoblocks sound best after 10 days. My SS phono-pre is always on - wall power for standby, NiCad for listening. My cartridges always sound better after 30 minutes.

@moonwatcher You say, "That "break-in" should be required of the manufacturer BEFORE they ship them out the door."

Agreed. My higher end Grado cartridge has had no perceptible change in sound, and as I was in contact with Mr. Grado himself, I know that it came direct from the factory as a special order. Hats off to Grado.

Built a set of speakers in Juiy. They sound different now than then, subjectively Better (now at around 200 hours of use)... as experienced by a 1/2 dozen people in our Vinyl Club, family members and myself. If it is a Placebo Effect, the PE has been consistant through variously aged people, the frequency of their exposure, Digital sources, Analog sources, different placement in the Room and other variables.

A very impressive Dummy Treatment...we are all fooled and happier for it. 

I merely note that if Zu Audio can offer free break-in before they ship to you, at their price points, it seems pretty lame for more "upscale" manufacturers to not do the same.  Speakers ought to be turnkey components.  You buy them, you plug them in, and you listen. You smile if they make you happy or you send them back if they don't. 

Forcing customers to do such long break-in periods does start playing into the psychoacoustics of mental accommodation, wherein you think they sound better because you want them to, and you've become used to them, not because they do by any objective measurements. 

And I have to ask you this:  If speakers change so much after 200 hours of use, what then of the next 4000 hours? How does a mass-spring-damper system "magically" know when to stop changing, or does it?   

Certainly physical components, yes.

But electrical current certainly changes wires and whatnot over time.  It’s called “electro migration” and eventually wears out wires and connections. Takes a ver long time.

It makes perfect sense that this process works on the front end for “good”.