Matched Pair RCA Black Plate 6AU7 Vacuum Tubes NOS-Testing Музыка Барокко Tube Two tested 56/57 where

Tube Two tested 56/57 where minimum (65%) is 40/40 and 100% is 62/62

new in box CBS-Hytron 8CS7 tested to spec on our Paul Hart-calibrated TV7/U

new in box RCA 6JU8A tubes tested to spec on our Paul Hart-calibrated TV7/U

Transconductance measured 59 for both tubes where minimum (65%) is 40

Tube One measured 59 while Tube Two measured 64 where minimum (65%) is 46 and 100% is 71

Matched Pair RCA Black Plate 6AU7 Vacuum Tubes NOS-Testing Музыка Барокко Tube Two tested 56/57 whereThis new old stock testing, perfectly matched pair of RCA black plate 6AU7 dual triodes was tested on our Hickok 800 for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 2600 2600 micromhos for both tubes. (New 6AU7s typically test within a standard deviation of 2400 micromhos). I am playing them in my Alan Eaton single ended triode amplifier (with adapters, not included) as I write and they sound great. These