Old AR drivers can't sound like they did when new! Why?

[Mexicomike]

It seems to be "common knowledge" that even if an oem driver is functioning and meeting specs, it does not sound as good it did when new. But how do we know this? It is also "common knowledge" that we don't know what a new AR 3a (for example) sounded like because there arent any new AR3As. So if we "know" that we DON'T know what a new AR 3A sounds like; how can we "know" that an existing old AR 3A driver(s) doesn't sound as good as it did when new? If we can't know what a NEW AR 3a sounded like, how can we know that an OLD AR3a doesn't sound like it (assuming crossover caps are OK/renewed).

Other than foam woofer surrounds (who's idea was THAT?) what is there to wear out in a properly cared for unit? Certainly I can understand that a driver or system that has been sitting in a damp basement for years may be in pretty poor condition but if one has been kept in a home and operating all this time, why would we expect the sound to be worse than new (again, assuming crossover capacitors are OK/replaced)

Acoustic instruments "wear-in" and the sound improves; seems to me it's possible that an old driver may exhibit better characteristics than a new one.

I am not trying to argue - just to understand how we can be so positive that they don't sound as good as new AND equally positive that we don't know what they sounded like when they were new.

My AR3As sound pretty dang good!

[soundminded]

It seems to be "common knowledge" that even if an oem driver is functioning and meeting specs, it does not sound as good it did when new. But how do we know this? It is also "common knowledge" that we don't know what a new AR 3a (for example) sounded like because there arent any new AR3As. So if we "know" that we DON'T know what a new AR 3A sounds like; how can we "know" that an existing old AR 3A driver(s) doesn't sound as good as it did when new? If we can't know what a NEW AR 3a sounded like, how can we know that an OLD AR3a doesn't sound like it (assuming crossover caps are OK/renewed).

Other than foam woofer surrounds (who's idea was THAT?) what is there to wear out in a properly cared for unit? Certainly I can understand that a driver or system that has been sitting in a damp basement for years may be in pretty poor condition but if one has been kept in a home and operating all this time, why would we expect the sound to be worse than new (again, assuming crossover capacitors are OK/replaced)

Acoustic instruments "wear-in" and the sound improves; seems to me it's possible that an old driver may exhibit better characteristics than a new one.

I am not trying to argue - just to understand how we can be so positive that they don't sound as good as new AND equally positive that we don't know what they sounded like when they were new.

My AR3As sound pretty dang good!

All things change with time. Manufactured materials invariably change for the worse. There are exceptions. We used to break in automobile engines by running them the first 10,000 or so miles cautiously. This resulted in machining the last few ten thousands of an inch so that valves and piston rings seated properly but in general, change brings deterioration. The enemy of manufactured materials are heat and moisture. Heat causes random motion of atoms and molecules to increase which in turn accelerates chemical changes. Moisture creates an environment for bacteria and mold to grow and these secrete corrosive enzymes which break down manufactured materials. It happens at a sub microscopic scale and the rate and consequences depend on the conditions and the materials. In a recent program on the discovery or history channel, they showed what would happen if human beings suddenly disappeared from the earth and there was nobody to maintain man made things. In a couple of hundred years, almost everything made by man would crumble. This includes huge structures like skyscrapers you'd think would be around forever. One of the last structures to fail would be Hoover dam which might last a few thousand years. There are some plastics which will last for many hundreds or even thousands of years, others designed to be biodegradable will only last a few years or decades at most.

Unfortuntately, experience shows that some of the materials in AR drivers deteriorate relatively rapidly. These include suspension components such as the outer suspension and polyurethane used in the tweeters. When these changes become extensive enough they result in significant changes in the mechanical properties of the driver such as the elasticity and therefore the FR and resonance points of the drivers. How do we know this has happened to the extent that none of the existing tweeters no longer meet the original specs? We don't. It's only a guess based on what has been observed by so many people looking at so many drivers. Some may have held up better and longer than others. But AR had very tight tolerences to their specifications and any drivers which did not perform within tolerance were destroyed so that theywould never see the light of day either by accident or by being stolen and sold as spare parts. Every driver made or outsourced was tested. We have photographs of mountains of destroyed drivers in barrels at the factory to prove it.

The difficulty of engineering and manufacturing replacement drivers depends on how much knowledge about the originals is available. If original drawings and specifications exist and the test procedures for acceptance testing were well documented, then that would be the best case. Often such documents are not available. Then what was likely the original design characteristics and intent must be inferred by careful forensic analysis of what is left of existing specimens. The process tries to imagine what the original must have been like to get it to where it is now. Expertise in material science and how component aging occurs for the various materials used is necessary. It's not a cheap process. Unless there is reasonable cause to believe that the effort would end up in what turns out to be a profitable investment, there is no reaons for anyone to undertake it. That is why persuading Vifa or anyone else to do it is unlikely. There simply isnt' a market for it. Besides, if anyone really felt AR3a was the best speaker that ever was and could persuade the market of it, newer versions using what has been learned in the last 4 decades could be developed instead. Unfortunately, we are among the last survivors of those who believed in them. When we are gone, the legend will die with us, the only trace left will be the AR3s in the Smithsonian right along with the other dinosaur bones.

[Guest pbda]

Excellent comments, soundminded. Thank you.

[AR surround]

All things change with time.

True. I doubt if I hear as well as I did when I bought my AR-9's almost 30 years ago. Perhaps one's hearing deteriorates at the same rate as one's beloved AR speakers. Ha!