[78-L] November 9, 1921

[Michael Biel]

  On 8/24/2010 8:51 PM, Royal Pemberton wrote:
> Since the early RCA home recording system involved embossing the soft
> plastic discs, I wonder how much of the sound has been lost from them
> through the years due to the material tending to spring back to original
> shape (if at all)?

I think I had even mentioned that possibility way back in my 1977 
dissertation.  I don't think we know or can know unless some took 
measurements many years ago of some discs.  I would think that there 
might be some differences depending on the heat of storage.  Also 
remember, there are two types.  The small white label s6-inch discs are 
not solid plastic.  They have a cardboard core under relatively thin 
celluloid or vinyl sheets.  The regular sized orange label discs are 
vinylite or victrolac which is supposed to be the same thing.  Lennick 
has said he has seen some of the Canadian ones with the greasy 
outgassing, but I don't see that on the U.S. ones.

Also remember that many dictating machine systems embossed on vinyl as 
well, Dictabelts. Gray Autograph, SoundScriber, Memovox, Edison Diamond 
Discs (the 7-inch red dictating machine discs in the 50s), Amertype 
Commando film recorder, and I believe, the Wagner-Nichols.  There is a 
possibility that the W-N cut a groove because it was of such high 
quality, but all the others embossed a groove on blank vinyl or 
celluloid.  I don't know of any of these losing their grooves, because 
while the RCA would possibly spring back to unmodulated grooves, these 
might spring back to blank!

Mike Biel   mbiel at mbiel.com