Valvo 12AT7 ECC81 Vacuum Tube For Your Univalve NOS-Testing 4th Quarter new in box Sylvania 5U8

new in box Sylvania 5U8 tubes tested to spec on our Paul Hart-calibrated TV7/U

These tubes have tall bases

Detector and First Audio 12AV6

new in box US-made 6GV5 tubes tested to spec on our Paul Hart-calibrated TV7/U

This hardcover book is in fair condition

Valvo 12AT7 ECC81 Vacuum Tube For Your Univalve NOS-Testing 4th Quarter new in box Sylvania 5U8This Valvo 12AT7 dual triode was tested on our Maxi Preamp II for shorts, gas, noise, transconductance and gain. There were no shorts, noise or gas. It will also be also as time becomes available on our Paul Hart calibrated TV7 U for a more familiar point of reference for most. Noise: 74 dB 75. 3 dB ( 92 dB is the Maxi Matcher's noise floor) Transconductance: 1400 1762; Gain: 53. 7 54. 4 where 50 50 is new. It sounded balanced, had excellent frequency