Which Telefunken 12ax7

FYI. . .Telefunken had TWO plants. One of them was in EAST Germany ("made in Germany") and had literally no access to fine metalurgy and so production was largely junk. LOTS of junk was produced. All say "Telefunken", all say "made in Germany", and all have a diamond logo on the bottom, and all have nearly the same packaging as the West German plant. True West German Telefunkens typically (this varies) have rather poor logo printing on the tubes. It is so confusing that I often prefer used "pulls" from McIntosh, Fisher, Eico, and Dynaco gear from the sixties. True West German Telefunkens typically last a lot longer than other tube brands (this depends on the circuit they are in), so if they test good, they usually are good. Neuteral in tone, detailed, and not at all rounded speaks for the sonic character. Be careful so as to not spend gobs of cash for the gobs of junky East German tubes that flood the market. Happy listening.

...are you sure about the Est German Telefunken's?They had factories just at Ulm and Berlin for the tubes....

if you've reached the point where you care about and can hear the fine points of such tubes, only listening in your own system can answer your questions.

Thanks Teajay, terrific review. Brent Jessee is a local guy so I'll definitely try to get a pair for audition alongside the Telefunkins.

Mcfarland, Thanks for the heads-up. I'm not sure how, but I'll try to determine which plant if possible.

Generally the East German tubes have thinner pins. A reputable dealer (such as Brent Jesse, Vintage Tube Services, etc.) will not, or should not, steer you wrong. See if you can find some good testing used pulls from old equipment. You can then use those to compare such things as the pins.