1 low noise tube) CV4003=M8136=12AU7 Mullard UK NOS large "O" getter halo 1962 (Wyteleafe plant) dirt was over entire tube - reboxed

1 section) 10.6ma Gm=2300

1 section) 11.0ma Gm=2300

Tested on Amplitrex

Good Ma range 8-10ma

Good Gm range 1800-2200

M8136 on front of tube

CV4003 on backside of tube

great midrange and good bass

Low Noise and not microphonic 

Recommended for

- Concert Fidelity CF-080LS Hybrid Line Stage Preamplifier

- Ampeg SVP-PRO Bass Preamp

- Velleman K4000 kit

- Audio Note CD2

- ROTH AUDIO MC4 MUSIC COCOON 2009

- Eastern Electric Minimax

- Hovland

- Schiit Vali 2