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Looper's Delight
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Richard Sales wrote: <snip> > I do have an unscientific opinion. I do not believe the sound of metal > instruments is because of aging but more because of the type of metal > (brass) that was used and how it was formed. <snip> > I think this is an argument, like politics and religion, which one can > not win. Maybe a real scientist can add some scientific data, but I will > still take my old Super 20 or Mark VI over any of the pretty new axes > that are on the market. A real scientist? I've managed to fool NASA into thinking so for quite awhile. :-) When this subject came up a couple weeks ago, I talked to a metallurgist friend about metal aging. He normally works on developing new alloys for jet engine internals. Come to think of it, that's probably pretty relevant, since jet engines and saxophones in operation are both full of hot air and make loud, annoying noises. It's been a long time since I looked at Art Benade's book on musical acoustics, so any real acoustics jocks on the list should feel free to offer corrections or howl in outrage. If memory serves, a textbook wind instrument has infinitely stiff walls, and its sound is determined by its shape, the mouthpiece, the player's oral cavity, the reed, etc. As you move from a textbook idealization to a real-world instrument, the walls are no longer infinitely stiff, and, if they become thin and compliant enough, start to contribute to the sound by selectively damping certain frequencies (the tone holes also provide damping, but that's another issue). So, in principal, the properties of the metal can affect the sound. These properties can change over time, although thermodynamics dictates that the changes usually happen slowly. During instrument construction, metal is typically bent, rolled and generally abused, which work-hardens it, building in internal stresses. The stresses can be annealed out by heat treating, but if that isn't done, stress-relief can still occur slowly over time via the motion of defects called dislocations, resulting in a softer metal. Also, depending on the specific alloy and its heat treatment history, additional phases may slowly precipitate out, forming small islands within the bulk alloy. These islands may coalesce over time, via a process called Ostwald ripening, to form fewer but larger islands. There's also the issue of surface treatment--most instruments are lacquered, but some are plated, and different platings sound different. This suggests that if the surface were to oxidize over time, it might affect the sound as well. I don't know whether this stuff would be enough to cause an audible difference over time; probably somebody at Selmer knows the answer. As a physicist, my understanding of this is pretty superficial, and a real metallurgist could probably offer a better explanation. Having said all this, I haven't noticed changes in the sounds of my seventies-vintage Mk VI soprano or tenor. Or, rather, any changes are likely masked by changes in reeds and mouthpieces, and the fact that aging seems to affect the player much worse than the instruments. Brian