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RE: I've read that the 12B4A is amazing

Posted by AJ on February 15, 2016 at 12:47:50:
No Marantz amp ever used the 12B4 input tubes or drivers. Marantz utilized 12ax7 and 6cg7 in the Model 2 and 6BH6 and 6CG7 in the Model 5 and 8B

12B4 is a medium mu triode which was used in tv sets for vertical deflection circuits

Tubes like the 6FW5 and 6FL6 were sweep tubes in horizontal deflection circuits for tv with significantly higher current capability

All of these were used in Futterman output circuits.