This is a 1957 Mullard GZ34 rectifier tube. It is the tv2 vesion, as shown by the metal base stamps. These are described as "the holy grail of rectifier valves". I can't find another for sale in the UK! It is in good working order, with output of the two plates within 0.5%. Sadly the printing has been almost rubbed away, but you can just see the remains of the Mullard logo and a "G". As a result of this I am selling it at less than it is probably worth. If you want the ultimate audio rectifier valve, this is it.
