“6N14-EB is a Special Quality EL84. This is NOS and the BEST EL84 ever made. The 6P14P-EB is a tube from Russian old stock. It was originally designed for the military to have long-life audio tube with low-microphonics, and not having to use the lower quality EL84 radio tube for this. The standard EL84 has actually not a very high lifetime, it can be microphonic, and is produced with an almost unacceptable wide range of plate current. The 6P14P-EB deals with all of these problems at the same time. This tube used to be very expensive when it was made! It was never before available for commercial use. NOS stocks of this tube have been released for public sales only recently, and stocks are low.”
The most incredible thing of those, is the heater tolerance which is 10%. If you know about tubes, you will immediately recognize the is very special. This is only so for tubes like ECC801S, ECC803S, etc, and some (very very ) few of the American noval tubes. All of these 10% tolerance tubes are small signal tubes that do not get very hot. Yet, you find here 10% for a tube like EL84. This is really special. Furthermore, the weight of this tube is 19 grams which is 40% heavier as regular EL84, like for instance the Philips NOS.