[78-L] 78-L Digest, Vol 3, Issue 4

[Pablo Varela]

Thank you for the info, after reading this, I'd try on an old turntable with a ceramic cartridge, and I'd compare with another old LPs and Dynagroove does it better. It's clear that late in the 1950 nobody expect that the LP were played with magnetic cartridge.
Best regards.
Pablo.
    

Dynagroove did use a groove size that was optimized for ceramic and 
crystal cartridges, and might be a little larger than earlier records.  
I am not sure, but it is possible.  What I do know about is that RCA was 
using several different grades of vinyl at that time, and some of their 
pressings from the 60s are VERY NOISY with a grain structure that can be 
seen if you look closely.  You can also hear it if you put the stylus in 
the ungrooved area of the lead-in and lead-out areas.  Black label pop 
albums that were pressed on the manually operated presses were the 
worst.  Usually a better grade of vinyl was used on the automatically 
operated presses.  Original Cast albums and the Vintage series usually 
also had the better grade of vinyl.  Red Seal also ususally had the 
better grade.  But ironically the best and quietest grade of vinyl was 
used on the Dynaflex pressings.  That is one of the reasons they could 
make them thinner.  They were always pressed on the automatic presses.

How do you tell the difference of which press was used?  The stamper 
holding bracket indication is about one inch in diameter for the 
automatic presses, while the manual presses have the deeper indented 
groove about a half inch from the outer edge of the label.   The  outer  
raised rim is also different.  The manual press has the higher part only 
in the lead-in area, while on the auto press the raised rim slopes 
gently down into a half-inch which extends into the groove area. 



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