Matched Pair RCA Black Plate 6AU7 Vacuum Tubes NOS-Testing Музыка Барокко new in box Triangle-A 1L4

new in box Triangle-A 1L4 tube tested to spec on our Paul Hart-calibrated TV7/U

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

perfectly-matched pair of Sylvania 6SJ7s was tested on our Paul Hart-calibrated TV7/U for shorts

This matched pair of Cunningham / RCA 6F5s were tested on our Paul Hart-calibrated TV7/U for shorts

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

Matched Pair RCA Black Plate 6AU7 Vacuum Tubes NOS-Testing Музыка Барокко new in box Triangle-A 1L4This 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