After rolling 6SN7 and ECC40 from the 1940's and 1950's, I am beginning to think that that period of time was truly the golden age of vacuum tubes in the West. Considering how much I like my 1961 Heerlen-made E80CC, I decided to try to find one from the 1950's. This tube was first introduced around 1952, so hoped to find one from the mid 1950's. Well, I managed to find and purchase one, and it arrived today. At the time I purchased it, I wasn't sure of the manufacture date. The vendor couldn't make out the entire production code, but did provide the first line, "WK3". With a change code of "3", I figured it was pretty early, as my 1961 has a change code of "8". I am pleased to discover that this one was manufactured in February, 1955. And further, I was surprised to discover this tube was manufactured in Eindhoven. The full code is WK3 45B.
I have the tube in my amp as I write this, and it sounds great. But then, recently, it seems almost every tube sounds great on first listen... time will tell.... :)
1961 on the left, 1955 on the right, with pinched waist (neck?) and D-getter