Sylvania 12AV7 Vacuum Tube Valve Black Plate NOS-Testing 17BZ3 T18 new in box Telefunken 6BL8

new in box Telefunken 6BL8 / ECF80 tube tested to spec on our Paul Hart-calibrated TV7/U

new in box RCA 36MC6 / 36MC6A tubes tested to spec on our Paul Hart-calibrated TV7/U

It comes with a box

I am playing them in one of my Radio Craftsmen SC-2 monoblocks as I write

Sylvania 12AV7 Vacuum Tube Valve Black Plate NOS-Testing 17BZ3 T18 new in box Telefunken 6BL8This 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