Audiophile Speakers with 25 yr + Longevity

Curious as to what a list of these loudspeakers which "probably won't require maintenance until your kindergartner has earned their doctoral degree" might look like...
Cones and domes will likely be more durable than stats, ribbons and other planar types.
Well, I would like to mention the older Mirage M series speakers. Not much for looks but they were very well made. The main drivers do NOT require new surrounds like Infinity speakers. I had a 20 year old pair and they sounded as new.
rubber surrounds, not foam surrounds is #1 for long life.
Foam surrounds WILL rot away after a dozen years.
Rubber may last a lifetime if no ozone or sunlight hitting them. Fabric also seems to last a very long time.
Old Magnepans had glue problems and needed regluing. Newer ones are not supposed to have that problem anymore.
Otherwise just about any speaker can last a lifetime. If you want to use them for a whole lifetime.
Plenty of old big 1950's speakers still in use..
Crossover capacitors can go out of spec over time and electrical joints can corrode. Large woofers with heavy magnets can sag and start to rub. Even rubber surrounds can dry out and lose flexibility which can alter bass performance. Air tight seals can dry up and leak. In general the speakers will still produce sound, but not as originally designed.
I bought my Magnepan MG 1B speakers in 1985. They have been to the factory twice... the first time when I blew the tweeters because the fuse was bypassed and the second time 10 years later when the repair needed touch up. The speakers are now handed on to my college age son. As long as you have a climate controlled environment Magnepan's will last... don't leave them at an un airconditioned location where the membrane will deteriorate from heat. The 1.7's I now have will likely be in my will 25 years from now.

10-29-12: Pdspecl
Well, I would like to mention the older Mirage M series speakers. Not much for looks but they were very well made. The main drivers do NOT require new surrounds like Infinity speakers. I had a 20 year old pair and they sounded as new.

A pair of 1996 Mirage M5si's still anchor my HT 7.2 surround rig, and I have no intention of sending them on, In fact, the speakers they replaced are also nearly timeless--ADS L1090 series ii. Both speakers use butyl surrounds on the cone drivers and the cabinets are very solidly made of thicker-than-average MDF.

The continued popularity and high resale value of both these brands is testament to their sound designs and durable construction. I bought my L1090s the year my daughter was born in 1987 and I have no doubt they'd continue to deliver today. I've seen plenty of 20-30-yr-old ADS speakers fetch $500-1500.
Tweeters that use ferrofluid in the magnetic gap can dry out over years causing (at first) an unexplained channel imbalance in the highs and then progessively both a more rolled-off HF response and decreased power handling...if you play them loud enough the tweeter voice coils can even burn out. The right kind of ferrofluid can be purchased and periodically used to "top off" your tweeters (every few years or so). People should be aware of this when they go to buy older used speakers that use ferrofluid since even most audiophiles don't recognize it as an owner's maitainance item and you could be buying or auditioning speakers that have never had that looked after. Once you add the ferrofluid (google it), the tweeters and their performance are entirely as good as new.
Quite a few older speakers with prosound-style drivers still work and work well. Vintage Klipschorns, Altec VOT, Valencia, Model 14, Model 19, JBL Paragon, Hartsfield, Model 4430, to name just a few. These range from 30 to 60 years old ballpark.

Ivan_nosnibor, My Hyperion HPS-938 speakers have 6.5" midrange with ferrofluid instead of suspension (spiderweb). Speakers are pretty new but I will face this problem in the future. Company itself, if still in business, may belly-up soon. I don't even know if tweeters have ferrofluid. Also, Wikipedia stated that ferrofluid has to be completely replaced with proper type. Are there any technicians that specialize in speaker repair?
I haven't actually seen an actual midrange that uses ferrofluid before, but one thing must be true: the magnetic gap itself cannot be designed to be sealed against contact with ambient air (not and still make the driver be able to move in and out of the gap), so that means the ferrofluid WILL eventually dry out and THAT means the manufacturer must have made (or left) some provision for someone to replace it when it does. In fact, that may even be so simple that you could do that and save yourself the headache and expense of going through a technician - after all, if you were going to send the driver in for repair, you'd still have to remove it from the cabinet yourself, right?? We may as well take a look at it and see how it was constructed.

But before doing that, first a word about the right kind of ferrofluid. For lack of any formal introduction into ferrofluid types, you might imagine that the specific type needed for loudspeakers is presumably something on the order of a "high-" or "very-high-" grade of product and that only a very specialized manufacture of it will do. Luckily, for audiophiles this not the case. Well...we really don't want LOW-grade ferrofluid, but avoiding that is really all we have to worry about. All ferrofluid is, is simply pulverized iron filings suspended in a "carrier fluid". That carrier fluid is normally ordinary mineral oil, nothing more. All the carrier fluid has to do is allow the iron particles to be suspended uniformly throughout the oil on its own, which mineral oil does, and to help take away the minescule amount of heat in the voicecoil, allowing for better power handling and HF response. Mineral oil-based ff does all this just fine, there is no need to ever seek out any kind of 'wonder' formulations of other carrier-oil-based ff's that were dreamed up (in more recent years) for manufacturing, industrial or scientific uses - they offer absolutely no advantage to us. The amount of voicecoil heat we're talking about is so low with respect to the mineral oil that, honestly, it would be like insisting on only using premium gasoline in a 1972 VW Beetle...a big expense for zero gain. The LOW-grade ferrofluid, OTOH, is made and used primarily for educational purposes - schools (down to the elementary level), labs or even to be made at home for amusement's sake (you can google all that for a better understanding). This type substitutes ordinary Kero Syrup (a food product) instead of mineral oil because it is more kid- and environment-friendly...of course, it breaks down much sooner than mineral oil. Just avoid this type. Mineral oil-based ferrofluid is mineral oil-based ferrofluid, the brand or price is generally not critical.

Now back to the mid driver. If you can remove it from the cabinet, look at where the cone connects to the voicecoil and the voicecoil fits inside the gap. Push gently on the cone and see if you can see the dark brown ferrofluid 'rise' up, or bead up in the gap as the voicecoil travels along the in-stroke inside the gap. If you can begin to see the ferrofluid at any point along the length of voicecoil travel, then that's a good indication that the 'ferrofluid tank' is indeed full and there's no present need to add any more. This would be the same for your tweeters if they use ferrofluid too (but, never directly touch a titanium tweeter dome or it will be damaged). As for the mid, try examining the driver, looking for how the cone/voicecoil assembly was attached to the magnet assembly in such a way that they could both be separated from each other, by way of removing the right screws, so that nothing "glued" or otherwise permanently sealed need be violated. If the vc/cone assembly truly couldn't be separated without breaking something, then look for some kind of hole, or screw that is hiding a hole, and see if that is an access to a ferrofluid reservoir. If there is no such hole, then remember: if it can be put together, it can be taken apart, and also place some confidence in the fact that if it were put together indeed without any provision for someone like you to both clean out the reservoir and then add the needed amount, then that would in truth be rather shameful engineering (a product designed to fail) indeed - not at all something I would be expecting from a company like Hyperion, so take your time if you have to and perservere in uncovering the way to get the magnet assembly by itself and have direct unobstructed access to the magnetic gap. One word of caution: when you're at the point of having removed the requisite screws and are about to remove the vc/cone assembly from the magnet, you may find they are still stuck together even though all the screws are out. Be aware that these 2 items have been held together under high pressure for a long time indeed. It's ok that it may take a little force to separate them. Just make sure you dont't damage anything delicate the moment the surfaces are "popped" off each other - the exact moment of which may be unanticipated.

None of changing ferrofluid is necessarily all that difficult, really. The first time is a puzzle when you have to find out how to disassemble things a bit, but after that it gets to be a piece of cake, really.

If you have the magnet by itself with gap face-up in front of you and under good lighting, look inside the gap where the ff should be. If along the circumfrence of the gap the surface of the ff (in cross-section) describes a 'u-shape' between the surface of the flat steel on either side of the gap, then that is the correct ff amount and the vc, once inside the gap, should displace enough ff for it to become about even with the steel surface of the magnet assembly while the vc is at rest. If the ff level is too low, or there is no ff left at all, the best thing to to do while you have everything disassembled is to go ahead clean out the gap as much as you can, before adding more. For most gap sizes, all you need is a few, pressed paper business cards (not plastic). Just insert one into the gap and run it around inside a few times and let it begin to soak up the ff. Remember: ff stains everything it touches, even your skin, so it's a pita in that regard. But, use as many business cards as needed until the ff begins to stop soaking into them. Be sure to get out as much grunge with them as you can. All this is about 10 or 15 min. per gap, usually. Adding the right amount of ff is best done with an eye dropper you can get at hardware store. No need to squeeze it - the magnetic pull will draw it straight into the gap. Too much in the gap can easily be removed by placing a paper towel over the face of gap and bleeding off the right amount. That's it. Just reassemble.

AFA your tweeters go, you may need to separate the magnet from the vc and just look carefully into the gap and see if there is any ff in it.

If none of this your cuppa, you can always fall back on repair service, there are a slew of places that can do this for you.

Let me know if you need more info. Regards. John
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:
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.
Earlier this year, I acquired a pair of Altec 846A Valencia speakers from the son of the original owner. Other than a little sun damage to the top of the cabinets (made less apparent by applying liberal amounts of Scott's Liquid Gold wood cleaner & preservative), these mid 1960's speakers are still going strong and will probably outlive me...
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.
I had Ohm Walsh 2s from 1982-2008 that were still going strong when I traded them in for newer models.

The OHM Walshes are most resilient. There are no exposed working parts. USe of wide range walsh drivers with very high crossover to a tweeter at 7khz or so makes then very hard to overdrive or stress. Plus, I received 100% of the original value of the speakers towards the trade-in using OHMs very favorable trade-in policy.

OHM has been around for about 40 years or so now and may be the only speaker company that still fully supports every speaker model they have ever made, offering repairs, upgrades and trade-ins wherever possible..
John, Thanks. I don't have problem now but like to take precautions for the future, before Hyperion goes bankrupt.
Mapman, it might be prudent to mention that OHM no longer has the qualified technicians to repair the original true Walsh drivers, and now offers trade ins towards a different type of speaker instead. And that the lack of "exposed working parts" makes repairs more challenging.
Most loudspeakers made today and if of hi quality should last 15-25 years. I have loudspeakers from the 1930s that still meet spec.
Tar fabric or paper is the longest lasting surround material not rubber.
Not quite 25 yrs but I've owned my Spendor S100's since 1990. They still sound fantastic!