mat@hou4b.UUCP (07/14/84)
Some years ago, when Columbia records were known for quality (before my time :-) ) they had people pull every thirtieth record or so off the line and play them. These poeple were allowed to change styli as often as they liked. They usually changed them after about four hours. Some management type had the discards checked under a microscope, and no wear was visible, but some kind of blind tests were done and the practiced listeners could indeed tell quickly how worn they diamond had become. By now, I'm sure that the proper microscope techniques were discovered. The question; a month or two ago I went to get my moving-coil cartridge replaced. The saleswoman checked it under an Audia-Technica microscope, which uses a small, powerful, light source on each side reflectiing off the groove-reading face to create a little dot. She asked if I was sure I wanted to replace it. I haven't got an elapsed time meter, but estimated that I'd played between 170 and 220 sides with it, so I said yes. She invited me to look at the microscope image, and compare it with the photos of what one should expect. The traces were ever-so slightly distorted, sort of like this: \ \ rather than like this: | | but clean, with no rounding, comet tails, or whatever. I said change it. Now for those who know about such things, did I read the microscope image correctly? Are such things meaningful? Etc.