Not sure what happened, but my amp suddenly sounds like poop

[Pumpkins10]

Had my crack and speedball working with no big issues for a few months now, but all of a sudden the sound coming from the amp sounds the same as that phasey no bass sound you get when the jack isn't plugged in all the way. Tried wiggling it around that that, and nothing. Looking inside, the tabs are all making contact with the jack, so I'm kinda stumped.

I've double checked the solder points and that, so yea. Help would be appreciated 

[Paul Joppa]

That's not really enough data to formulate a theory about the cause.

How about the resistance and voltage checks?

[Nathan]

Tube failure

[Paul Birkeland]

Tube failure

This doesn't generally happen overnight, and sets in so slowly that it can be hard to detect without comparing your current set against a fresh set.

A voltage check would be helpful.