Matched Pair RCA 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing January 10 2021 It has an engraved /

It has an engraved / stamped base

It is dead quiet when the preamp is muted and has excellent frequency response and sound-staging

GE-BRANDED 17EW8 / HCC85 tubes tested to spec on our Paul Hart-calibrated TV7

Two are 1X2C and the other three are 1X2B

Matched Pair RCA 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing January 10 2021 It has an engraved /This new old stock testing matched pair of RCA 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 43 while Tube Two measured 46 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