(!) (Best Single) 7247=12DW7 Amperex Globe Logo by Matsushita Japan NOS 1967 similar sound to Mullard (1.5ma and 11.6ma) (High mA and Gm)

7247 Amperex Globe Logo by Matsushita Japan ribbed plates NOS 1967 similar sound to Mullard

12AX7 Section = 1.5ma Gm=1800

12AU7 Section = 11.6ma Gm=2300

Tested on Amplitrex

12AX7 Section Good = 1-1.2ma Gm=1600-1800

12AU7 Section Good = 8-10ma Gm=1800-2200