Matched Pair General Electric GE 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing ECF80 T28 These two Arcturus gray bottle

These two Arcturus gray bottle type / number 41 tubes tested as follows on our Paul Hart-calibrated TV7/U:

new in box US-made 6CY5 tubes tested to spec on our Paul Hart-calibrated TV7/U

This lot of five RCA new old stock

had excellent frequency response and was very quiet

it has excellent flashing

Matched Pair General Electric GE 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing ECF80 T28 These two Arcturus gray bottleThis 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