The Great 78 Project over at the Internet Archive has been professionally digitizing old 78 RPM records for a while now. These records were all made between 1898 and sometime in the 1950s. Over 20 collections have been selected for digital access and physical preservation with the help of George Blood, L.P. and the Archive of Contemporary Music. So far about 26,000 of the 78s have been added to the Internet Archive. Each disc has about 3 minutes of audio per side. Most of the discs are made from shellac and really quite brittle, perhaps even more brittle than today's digital formats.
(Score: 5, Interesting) by anotherblackhat on Monday August 14 2017, @06:34PM (2 children)
Some math;
Assuming
78 RPM
3 minute length.
4 inch radius (10" record, with a 2" diameter center)
78 RPM * 3 minutes = 234 revolutions
234 / 4 = 58.5 tracks per inch.
If your scanner can do 1200 DPI, that's about 1200/58.5 dots or 20
log2(20) = 4.3.
So less than 5 bits per sample, which is way better than I expected, but I'd call 5 bits per sample "lousy" not "perfect".
Those old records were designed to have a heavy needle resting on them.
Modern pick-up heads are so light by comparison that they are unlikely to cause noticeable wear after one or two plays.
Laser Interferometry can measure about 10-12 meters.
That's 6 orders of magnitude better.
Enough to get 25 bits per sample, which is probably better than your ADC.
(Probably better than the vinyl used to make the record, too.)
(Score: 0) by Anonymous Coward on Tuesday August 15 2017, @03:36AM (1 child)
Some 78 RPM records were made of vinyl, but shellac was much more common.
(Score: 0) by Anonymous Coward on Tuesday August 15 2017, @04:09AM
...as mentioned in the summary.