Uh oh, something is wrong with my 18 watt

[zeegler]

When it's been on for a few minutes, I get this sound like a wave coming in. It gets louder until it almost drowns out the guitar sound. I swapped out the pre-amp tubes, and it wasn't that. Could it be my power tubes? I don't have any other EL84s to check with. What else could it be?

[Twisteramps]

Hey Zeeg, email me. We'll figure it out.

Pete