The latest batch of these are a big change from earlier batches. These now have high gain, even higher than an ECC83, and nice curves.

The info is in the same place as always in the 12AX7 area of my website, where this has been updated.

If you think this tube looks like a Telefunken NOS, in the test update, this is explained too.

By the way, for you folks buying "NOS telefunken 12AX7" tubes, be sure to check the tube base for the diamond in the glass, as there are a lot of counterfeit tubes out there that are these, with Telefunken silkscreening.