Matched Pair General Electric GE 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing ECF80 T28 They tested 51/52

They tested 51/52

This trio of Toshiba output tubes was tested on our Maxi-Matcher in Real World Conditions with 400 volts on the plates and a bias of -36 volts for shorts

This lot of five RCA new old stock

There was some rumble on Side Four that I found annoying

They tested as follows: 55

Matched Pair General Electric GE 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing ECF80 T28 They tested 51/52This new old stock testing matched pair of GE 12B4A tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Tube One measured 44 while Tube Two measured 48 where minimum (65%) is 32 and 100% is 49. Wish I could tell you how they sound, but I don't have any equipment that uses these. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE ALSO SEE OUT ETSY