Newbie: Thanks for your help -- what appears to be the original label on the tubes I have is in the form of a replica tube with three sort of halo-like circles around the top part. The tube is identified in the same color (as the replica tube label) ink as: Ecc81 -- ARS appears to have stamped 12AT7 on the tube. Any clues as to who original manufacturer might be?
Thanks again for your help.
Thanks again for your help.