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Originally Posted by jdandy

Charles.......These tubes you are calling Telefunken are Black Diamond Telefunken Elektroakustik tubes. Telefunken Elektroakustik is a trademarked name for a particular line of JJ Tubes. They are not Telefunken tubes. There is a difference.

Dan, you may well be right, but I'm simply going by what they're called by Telefunken, Tube Depot and Magnum Dynalab. This is off Telefunken's website:

The TELEFUNKEN Black Diamond Series tubes are built in the JJ Electronic Factory in Eastern Europe based on their existing models. The Black Diamond Series tubes go through an extensive multi-tier testing and quality control process, as well as a cryogenic treatment in the USA to ensure they are the best representation of European made tubes. Each vacuum tube is burned in for 24 hours, tested for all critical parameters, cryogenically treated, and tested a final time. TELEFUNKEN Elektroakustik guarantees this by branding them with the legendary diamond logo.

And . . .

TELEFUNKEN's Black Diamond Series tubes have been screen printed with black ink to clearly differentiate them from the original, white inked diamond-based TELEFUNKEN tubes, originally produced in Germany in the early and mid 20th century.

There's other information, but this is enough to quote. I don't know how much Telefunken's involved with the actual tube manufacture, but the Black Diamonds don't sound the same as the JJ tubes I have, that's for sure. As for the Mullards in use currently, they seem to be doing okay with the C2300's treble set to -2 and the Shunyata Venom 3s as a power cord. But those two changes make me wonder if the Black Diamonds should get another chance.