Audiophile Speakers with 25 yr + Longevity

John, Thank you very much. It doesn't sound that difficult. I have one spare (upper) cabinet damaged/crushed in shipping. Midrange speaker is broken into pieces (plastic frame) but I can play with it. Some details of the construction are here: http://www.enjoythemusic.com/superioraudio/equipment/1104/hyperionhps983.htm

I own a pair of Thiel 3.6 speakers from 1995 and they sound better than ever. Of course, my gear has improved over the years. I've been having trouble replacing these speakers with new ones as they're hard to get rid of.

I've always had dogs with whipping tails. Over time, the dust caps on my woofers have received blows, but cosmetic problems only. Then a final blow that caused distortion from one woofer. I removed (unscrewed) both woofers, sent them to Thiel in Kentucky, and they replaced the caps. So, for $80 I was back in business.

Like I said, hard to get rid of.

Kenneythekey, suggests a very good point. You might want to stick with a company that has earned the reputation for good customer service and appears to have the legs to continue. Thiel is nonpareil in this regard. I use even older 3.5's, and would need to spend many times their costs to get better performance. Yes, a couple of drivers needed maintenance over the years, all done gratis minus shipping costs, despite being well out of warranty. I've been told by more than one Thiel rep that the even older CS 2's have been their most durable product to date. Just don't be foolish and over drive your under powered amp into clipping.

Duke mentions vintage Klipsch, and I can back that up. I had a pair of Klipshorns for almost 25 years. I pulled the woofers out (they are enclosed inside the cabinet) for inspection prior to selling them and much to my surprise, they looked brand new!
Zu Definition (according to their website) has a life expectancy of 100 years on the cabinet and drivers- even in sunlight.

Kijanki, saw the photo and diagram of your driver, but couldn't see how to disassemble it though. If you're still stuck, you can contact someone at Hyperion and ask...that would be a reasonable expectation of anyone to get some kind of answer on it from them.

BTW, adding ff to any driver (if the practical matter of being able to service it every so often can be worked out) is technically a very good idea. What is not generally understood by audiophiles is that ff greatly flattens out the impedance curve of the driver, presenting a much friendlier load to the amp. But, hopefully you can figure out how its done by studying the driver.