Ecc8312ax7 double triode valve edicron 12ax7eh high mu double triode valve triode valve b9a base 126v heater voltage 300ma heater current 15ma anode current 250v anode voltage low current smaller anode and low microphony and is especially suitable for instrument amplification intended for amplifier applications such as phase splitter cathode follower and low level audio applications edicron 12ax7eh ecc83 valve