Sylvania 12AV7 Vacuum Tube Black Plate NOS-Testing Sylvania NOS-Testing steel plates and steel suppost

steel plates and steel suppost rods

perforated plates

BECAUSE OF THE BIZARRE

I played them with adapters (not included) in my Radio Craftsmen RC-2 monoblocks and they sounded great

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 steel plates and steel suppostThis 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