Ecc8312ax7 double triode valve edicron 12ax7lps high mu double triode valve triode valve b9a base 126v heater voltage 300ma heater current 15ma anode current 250v anode voltage low current large anodeplate version spiral filament ideal for audio applications intended for amplifier applications such as phase splitter cathode follower and low level audio applications edicron 12ax7lps ecc83 double triode valve