Sylvania 12AV7 Vacuum Tube Black Plate NOS-Testing Sylvania NOS-Testing new in box RCA RCA

new in box RCA RCA 3AT2 / 3AT2B / 3AW2 tubes tested to spec on our Paul Hart-calibrated TV7/U

This trio of RCA black plate 12AU7A / ECC82 dual triodes was tested on our Paul Hart-calibrated TV7/U for shorts

This lot of six Sylvania number / type 58 stamped- / engraved-base tubes was tested on our Paul Hart-calibrated TV7/U for shorts

steel plates and steel suppost rods

These six US-made 6S4A tubes were tested on our Paul Hart-calibrated TV7/U for shorts

Sylvania 12AV7 Vacuum Tube Black Plate NOS-Testing Sylvania NOS-Testing new in box RCA RCAThis new old stock testing Sylvania 12AV7 dual triode was tested on our Jackson for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 116% 104% where minimum (65%) is 70% 70%. This tube has black plates; a horseshoe getter and terrific flashing. I am playing it in Bottlehead Crack headphone amplifier as a 12AU7 substitute and it sounds excellent. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE