You are looking at an excellent, very strong matched pair of prized Telefunken Ulm Germany ECC803S gold pin, halo getter tubes with twin getter supports. They are in superb condition, please note that here are nine photos. The printing is perfect on the first NIB tube - it has the Ulm production code U9208101a and the embossed number 13 between the pins. The second has the number 6 between the pins, it tests much stronger than nominal new measure but has lost it's print along the way. These legendary tubes are the real deal - the ultimate 12AX7 tube. You cannot find any better - over the years I have tried all of the 12AX7 variants but these are the ultimate best by a large margin. They have the embossed diamonds between the gold pins and the box still has the old Telefunken sealing tape on it. There is no better 12AX7 on the planet and these are very strong so are good for 10,000 hours depending upon your application.
I bought these beautiful tubes 25 years for a premium and they are part of my personal collection. I have briefly listened to these tubes in my pre-amp for noise and they sound sublime - absolutely quiet, superbly detailed but not harsh or bright whatsoever. They measure significantly stronger than new and very well matched on our AVO Mk IV for current draw and mutual conductance. Tube 1 (NIB) - 1.7/1.8 & 1.7/1.8. Tube 2 (Worn print) - 1.8/1.8 & 1.8/1.8. These are wonderful, very strong tubes as nominal new measure on our AVO Mk IV for the 12AX7 is only 1.2/1.6.