I may have a problem here, I have a quad of 12B4/As and I think pairing a 12B4 with a 12B4A will REALLY screw things up.
As I understand it the "A" version is a "slow start" version, the 'standard 12B4 is not. Paralleled on the outputs one will come up to temperature well before the other, drawing more current initially before the other....Bad idea? Smokin' bad idea?
_______________________________________________________Rick.........
As I understand it the "A" version is a "slow start" version, the 'standard 12B4 is not. Paralleled on the outputs one will come up to temperature well before the other, drawing more current initially before the other....Bad idea? Smokin' bad idea?
_______________________________________________________Rick.........
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In 7 and 9 pin mini tubes, the "A" type suffix indicates controlled heater warmup time. That is of consequence ONLY when series heater strings are employed.
BTW, do you have heater current to spare? If so, get the nasty, non-linear, 12AU7 out and a linear 12BH7 in.
BTW, do you have heater current to spare? If so, get the nasty, non-linear, 12AU7 out and a linear 12BH7 in.
Eli.........I have a 3A heater, the four 12B4s' will take 2.4A of that....I have a 'spare' TX split-bobbin at 12VRMS that I want to run thru a 317 to run the 12XXX. I have a AX and an AT .....I'll assume the AX runs "too hot"....I don't know about the AT...............don't have a BH. If I can readily get a BH........Is it a drop-in or do I have to re-bias??
__________________________________________________________Rick.......
__________________________________________________________Rick.......
A 12BH7 will go in a 12AU7 "hole" without any wiring changes, IF sufficient extra heater current is available. The 12BH7 draws twice the heater current.
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