Sylvania 12AV7 Vacuum Tube NOS NIB Black Plate For Your Bottlehead Juan Rosenkavalier They have engraved / hot-stamped

They have engraved / hot-stamped bases on is Champion-branded and the other is Zenith

They measured 86/82

straight-bottle bottle variety

These six new old stock

Sylvania 12AV7 Vacuum Tube NOS NIB Black Plate For Your Bottlehead Juan Rosenkavalier They have engraved / hot-stampedThis new old stock, new in box Sylvania 12AV7 dual triode was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 41 42 where minimum (65%) is 21. This tube has black plates; an O getter; terrific flashing and GJ MVWV date codes. I am playing it in Bottlehead Crack headphone amplifier as a 12AU7 substitute and it sounds fine. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES.