Bieworm wrote: ↑Mon 01/16/23 6:25 am
chaliapin wrote: ↑Mon 01/16/23 2:47 am
Tubes in sockets 3 and 5 currently.
Thanks Josh, I'll do as you suggest.
3+5????
Then each tube has a separate 150R cathode resistor. That's bad!
They should share one 150R (or preferably 180R) per pair. You should put tubes in V3+V6 or V4+V5... try that! I hope you didn't ruin those 2 good tubes too... they have been pulling twice the current they are supposed to pull.. hence your redplating and excessive hummmmmmmmm
36W chaliapin.png
Actually, you're half right. He can't have just 2 tubes in without changing the cathode resistors, that is why he's redplating. I was mistaken when I looked at it previously, just opposite of how you were mistaken lol.
But he can't put them in as you suggest either. You have to consider the OT as well (refer to the schematic).
What he should do is rewire 3+5 to share a single 180 ohm resistor until he gets more tubes (or more resistors) and he can wire according to the schematic.
To make the amp switchable between 2 or 4 tubes, he'd need to user higher value cathode resistors, and use 4 (1 per tube).