This matched pair of GE 6SN7GTB dual triodes was tested on our Paul Hart-calibrated TV7/U for shorts, gas and transconductance. There were no shorts or gas and transconductance measured as follows:
Tube One: 75/70
Tube Two: 79/74
Bogey: Minimum (65%) is 50/50; 100% is 77/77
Physical Characteristics:
Bases: tall
Bottles: medium height
Date Codes: 56-13 and 58-43, respectively
EIA Factory Codes: 188-4 and 188-5, respectively
Getters: mid-bottle, harp
Flashing Quality: excellent
Mica Spacers, Bottom: smooth, rounded rectangles
Mica Spacers, Top: smooth, rounded, irregularly-crenelated circles
Plates: gray ladder plate
Special Features: white labels
Support Rods: copper
I have played them in my Radio Craftsmen RC-2 mono blocks and they are dead quiet when the CD player is paused and have excellent frequency response, sound-staging, and dynamics.