Matched Pair RCA 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing 7 Lot Of Seven The pressing is quite-quiet with

The pressing is quite-quiet with little surface noise and only the occasional pop and tick

new in box Sylvania 12AV7 dual triode was tested on our Paul Hart-calibrated TV7/U for shorts

THERE ARE NO MANUFACTURERS TO TAKE PRODUCT BACK BECAUSE OF DESIGN FAILURES OR QUALITY-CONTROL ISSUES

Transconductance was 1900 for Tube One and 1800 for Tube Two where new/nominal is within one standard deviation of 1900

Three of these four new old stock

Matched Pair RCA 12B4 12B4A Vacuum Tubes Valves Black Plates Copper Support Rods NOS-Testing 7 Lot Of Seven The pressing is quite-quiet withThis new old stock testing matched pair of RCA 12B4 tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Tube One (12B4, harp getter with sheet) measured 44 while Tube Two (12B4A, O getter) 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