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!!  

sal1963

For what it's worth, Andrew Jones was quoted as stating it's not a big deal.  

Yes, break-in of any mechanical device is real. What is wrong is with manufacturers making YOU do the break in. Now, speaker guru Andrew Jones says that 90% of most break-in can occur in the first 10 hours for a well-designed driver.

OK, that sounds reasonable. What is not reasonable is manufacturers selling speakers requiring 200 hours or more to break in. This would put most people well into the end of the return period - perhaps beyond it. I mean, let’s face it, not everyone is going to buy a pair of speakers, wire them out of phase and put them in a basement playing Ted Nugent at 100dB for 200 hours. Not even counting the small amount of electricity used.

No. If a speaker manufacturer is foisting such poorly designed products on consumers they shouldn’t be patronized. I know I’ll never buy any speaker with such a reputation. The "recovering audiophile", Andrew Robinson, and his wife got into a discussion about this topic several months ago and concluded the same. 

That "break-in" should be required of the manufacturer BEFORE they ship them out the door.

Sure it’s real. But another thing that’s real is your brain adjusting to a new sound. We all have a mental template of how something should sound and over time, we adjust our brains to the nuances of different gear. 
 

In my opinion , I’m sure it can be measured with instruments as being real. But, can those measured differences actually be heard or just our ears and brains adjusting to the new component/ speaker?

Here’s a good test:  Buy a set of used speakers. If they have been used for several months, years or even decades, they can seem to change their sound over the first few days in your existing system, even though they are fully broken-in. That’s just you adjusting to how they sound.