(!!!!) (Single 1950's) 12BH7A RCA branded Westinghouse narrow black plates NOS "U" getter mid-1950's (10.6/7.4ma) (1st series made)

1 low noise tube) 12BH7A RCA branded Westinghouse narrow black plates NOS "U" getter mid-1950's 10.6ma Gm=3100 7.4ma Gm=2500   1ST SERIES MADE - VERY RARE SINGLE TUBE NOT A PAIR   Tested on Amplitrex Good NOS Ma range 7-12ma Good NOS Gm range 2400-3200 Low Noise and not microphonic   Recommended for - McIntosh- VTL- Manley- Kora Hermes DAC in place of 12AU7- Octave M90 mono amps (http://www.octave.de/)- BLACKSTAR HT-5 (replacing Sovtek)- Luxman MA-88 amp- Requisite Audio preamp- Teletronix LA-2A Compressor/Limiter- Art Audio Diavolo amp- Ray Samuels- Kendrick Solo 7- Valvet L1