Help with diagnosis

[fusionbear]

I built an amp for my son that has been working great until this weekend. He was complaining that the volume dropped considerably. I played it and sure enough, you could put the volume at noon and it would barely be considered loud. Before, you could put the amp at 10 O'clock and it would shake the whole house. Any ideas. I will pop the hood tomorrow after work...

Here is the build thread:

https://tubeamparchive.com/viewtopic.php?t=13610

Thanks!

[eddie25]

Yeah, a tube... that amp sounds great by the way, dig those clips.

[Structo]

First suspect in a tube amp is always a tube.

When troubleshooting start at the output and work towards the preamp using process of elimination.

[fusionbear]

PI Tube died. That's what I get for using old tubes...

Anyway, while I had the amp open, I went and redid the filament wire to come from above the preamp tubes and removed the rectifier from the filament power. No more hum and less parts that can fail...