There were actually Telefunken 6AS7Gs. They are quite rare. If I recall right, they have brownish bases.
OTOH, there *are* generic Russian tubes *marked* as Telefunkens!! So you have to watch it, and IMO you will not see any huge improvement with the power tubes. You are usually better off messing with the driver tubes to improve the sound, at least with our amps.
FWIW if you do find Russian tubes marked as Telefunken, they are fine tubes, no better or worse that than your regular Winged C tube, which is a good tube. I just don't think it would be worth it to pay extra for the name on the side.
OTOH, there *are* generic Russian tubes *marked* as Telefunkens!! So you have to watch it, and IMO you will not see any huge improvement with the power tubes. You are usually better off messing with the driver tubes to improve the sound, at least with our amps.
FWIW if you do find Russian tubes marked as Telefunken, they are fine tubes, no better or worse that than your regular Winged C tube, which is a good tube. I just don't think it would be worth it to pay extra for the name on the side.