GIven the age of those RIAA bulletins, I'm not surprised that they are not in metric units. Bulletin 3 is dated 1963 and Bulletin 4 shows the RIAA address with a New York City postal zone, not a zip code!
I wonder, since "vinyls" (as my kids persist in calling them) have made a bit of a comeback, whether RIAA might "re-engineer" their standards in SI units someday. Jim On Friday 2004 January 02 00:25, Bill Potts wrote: > The Recording Industry Association of America (RIAA) has a standard. It's > at http://www.aardvarkmastering.com/riaa.htm. > > Not surprisingly, it's not metric. However, so-called 12", 10" and 7" > records are all slightly smaller than their usual designations would > indicate. The nominal diameter of a 12" record works out to be 301.625 mm. > 10" is 250.825 mm. 7" is 174.625 mm. > > Interestingly, nominal diameter is always 1/8" less than advertised > diameter, with a tolerance in the positive direction only of 1/32" (0.794 > mm). > > Bill Potts, CMS > Roseville, CA > http://metric1.org [SI Navigator]
