Baldwin Select Sylvania 12AU7 12AU7A ECC83 Vacuum Tube Valve With An Introduction I am playing them as

I am playing them as I write in on of my Sound Craftsmen RC-2 monoblock amplifiers with RCA Living Stereo's CD of Bartok's "Concerto For Orchestra

This industrial-grade GE 6679 / 12AT7 dual triode was tested on our Paul Hart-calibrated TV7/U for shorts

matching 9-39 date codes

but that was the fashion back in the 1940s

new in box GE 6BK4 / 6EL4 tubes tested to spec on our Paul Hart-calibrated TV7/U

Baldwin Select Sylvania 12AU7 12AU7A ECC83 Vacuum Tube Valve With An Introduction I am playing them asThis Sylvania MANUFACTURED, Baldwin BRANDED and SELECTED 12AU7A ECC82 dual triode was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured an almost perfectly balanced 82 84 where minimum (65%) is 56 56 and 100% is 86 86. This tube has narrow, gray, 16 MM plates; excellent flashing; a top, O getter; copper support rods; excellent silkscreening and 312 132 provenance date