Sylvania 12AU7 12AU7A NOS-Testing Copper Support Rods Triple 3 Mica For Your Bottlehead Univalve Chad Mitchell Trio but not in guitar amps

but not in guitar amps and other environments with loud noise and/or excessive vibration

Tube One (missing centering pin / keyway): Tube Two:

Five are 6S4As and one is a 6S4

This lot of three Ken-Rad 6D6 tubes was tested on our Paul Hart-calibrated TV7/U for shorts

There were no shorts or gas

Sylvania 12AU7 12AU7A NOS-Testing Copper Support Rods Triple 3 Mica For Your Bottlehead Univalve Chad Mitchell Trio but not in guitar ampsThis Sylvania triple mica 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 73 79 where new nominal is 50 50. This tube has two additional vertical support rods; an additional mica spacer for low microphonics; crenelated, round mica spacers and excellent flashing. I have played it in my Bottlehead Crack headphone amplifier and it sounds