This one actually comes from another member of my listening group. He is comparing the current Chinese version to the Russian version of the 6AS7. He has noticed that the construction of the tubes varies slightly with a different base and other minor construction observations. He is currently testing a batch of them to see if one is different from the other and if any generalizations can be made.
Has anyone out there formed any opinions on the differences between the tubes? We have noticed that the pricing of the Russian tubes has been increasing. Not entirely sure why.