Tube amp Crackle-like distortion

[MonkHouse93]

I have a completed 5F1 champ circuit, with a switchable bypass cap on pin 8 of the 12AX7. I was playing it when a flash of lightning followed by rolling thunder occurred, and the next thing I know it starts making this crackling distortion and it would even oscillate when i play high notes around the 12th fret. I tried another set of tubes, the easiest thing to address, to no avail. My next thought was something that's directly connected to the power supply. I did a little research and came across a page that mentioned what seemed to be my issue and one possible solution was to address the coupling caps. I changed them out, and the oscillations went away but it still crackle-distorts, so perhaps there's a couple issues it's having and I've managed to figure one of them out. . .
the page also mentions to check out the plate resistors, cathode resistors, cathode bypass caps, grid resistors, and to be honest besides throwing an ohmeter over the resistors and seeing that it still shows me the expected value and seeing that the caps don't show a short circuit, I'm not sure how to test if these things are failing. . . the switchable bypass cap in the preamp i'm thinking isn't an issue because the distortion is present with it in and out of the circuit. I'm not sure about the 6V6 bypass cap however.

Here's a video of what it sounds like

thanks anyone who has any suggestions

[Enzo]

First, connect it to a different speaker just to make sure the speaker didn't freak.

That sounds like either arcing or parasitics if it is in the amp.

A meter cannot tell you if a cap is leaky or breaking down at voltage, nor can it tell you those things about a resistor.


If you have another output transformer, I would disconnect the one in there and clip in the other one and see if the problem remains. Lightning bolt COULD have instigated an arc in the transformer at high voltage.

[MonkHouse93]

That's a different speaker than is in the cab so I'm pretty sure that's not the issue. . . I don't quite have a champ OT on hand, but I do have an OT meant for use in a princeton style amp with dual 6V6 output. . . If I hooked up only half of the primary, like Blue and Red and left the Brown hanging, could I use that to test?

[MonkHouse93]

So I went along and used that OT I had lying around and the amplifier worked just fine, thank you Enzo!