Here is an excerpt from Acme, who make very high quality bass guitar enclosures. as you may know, bass amps put out some monstrous amounts of LF.
Q. What about breaking in my new woofers?
I played my Series I Low B2 with the new speakers I installed from you on a gig last night. Unfortunately the first thing I noticed is that is that the volume is lower and there isn't as much low end as on my Series II Low B2. I believe it could be because the Series I was tampered with by my 2 year old daugther shortly after I received the replacement 10" speaker from you. Long story.
A. The woofers in our Acme Low B Series II models have a break-in period. The surrounds on these woofers have a higher stiffness new-out-of-the-box than they do after some hours of use. This has two real-world consequences.
The first is that the ability of the systems to reproduce the lowest notes doesn’t reach it’s full capability until the surrounds have been loosened up by being used.
The second, and perhaps more important consequence, is that when driven to their maximum excursion, the woofers are much easier to damage when they are new, than after they’ve been broken in. It is more likely that the cones will be overstressed the when the speakers are brand new, than at any time after they’ve been used.
How much break-in time is necessary? I have broken them in using a sine-wave generator in less than three hours. I believe that whan playing bass, it is very difficult to predict how long it would take for a specific person to do it. It depends on your style, and how loudly you play. My best advice is to start slowly, and work you way into it. Within reason, of course, the longer, and the more gradual the better. But please do your best to loosen up the woofers before you get into any serious slammin.’
The reason I have chosen to point out these concerns about breaking the speakers in, is because just lately, I have had two customers damage their woofers within the two-week trial period. This was unheard of just several years ago. The woofers are the same. But I believe that the availability of incredibly powerful amplifiers, even more than just a few years ago, has sort of changed the landscape.