Tube Amp Archive

When the problem follows the tube, it's a pretty sure indication there is a problem with the tube. The question is whether the tube was bad to begin with or if there is some other problem that caused the tube to go bad. You may find after a time that the other tube red plates if there is a problem ...

Sorry, still no photo but here is the voltage chart: V1 12ax7 Pin# 1: 145 2: 0 3: 0.9 (this seems super low) 4&5 heaters 6.2 ac 6: 143 7: 0 8: 0.9 9 heater V2 12ax7 Pin# 1: 221 2: 35.5 3: 72.8 4&5 heaters 6: 218 7: 35.1 8: 72.8 9 heater V3 el84 Pin# 3: 11.3 4&5 heaters 7: 360 9: 330 V4 el84 Pin# 3: ...

Useful homework to do before and during your reunion with your amp: Before: read up on the "divide and conquer" method of troubleshooting. If you've got another amp kicking around, that let's you further troubleshoot. During: take a full set of voltage readings and make a chart. Fun fact: you can d...

vibratoking wrote:

Any areas that I should do a close up of?

Yes

Which ones? Preamp sockets? Preamp wiring on the turret board?

pic's or it didn't happen. did you swap tubes out of the amp, or just move them around? when you bypassed the MV mod, did you re-insert the 220k load resistors? i can usually touch pre-amp tubes as soon as i turn the amp off. they are warm but not usually hot. power tubes get really hot to the touc...

Hey everyone! I used to mod tube amps for a while, but I would pretty much just mess around with the preamp stage to change voicing. A few months ago I decided to do my first scratch build using a Marshall 18w lite schematic, with only mod being a post PI master volume. I am finally done, and when I...