[Skylab]

KG knows a zillion times more about this than I do, but the 6BL7 draws a lot more heater current than the 6SN7 which tHe MPX3 was designed for. If you want to reduce stress on the amp, use the 6SN7.

Personally, though, seeing that pic, I would use the amp at all until getting it repaired.

 

[MarconiSalad]

Thanks to Miguel, Wayne and Kevin. Replaced diodes in MPX3 with rectifier bridge mounted on back of case. Solder had migrated away from board with cooked diodes. Was able to remove some diode leads without heat. Added bleeder resistors to C54,C55. Replaced Sprague Orange Drops at C3, C103 with Gudeman PIOs while I was there. MPX3 sounds great, running fine. (No more 6bl7's)

 

[mrarroyo]

^ Nice going! Now enjoy the fruits of your labor.