Calling all Gear Gurus/Amp Technicians!

A while back my beloved Peavey Classic 50 2x12 suddenly began making this horrendous noise during a rehearsal.

Unfortunately I've not had the time to have it looked at professionally, but I thought I'd take a quick video to see if any of you guys out there could help me out with diagnosing the issue!

As you can see in the video, there is no guitar plugged into either of the inputs. All tone controls are set at 12 o'clock, and all volume and reverb controls are set at 0.

(free bump day)

I'm not an amp tech but that definitely sounds horrendous. I don't think I've heard an amp make that kind of noise before.

(reposting link here)

Here is what I would do if I were you.

*Take amp to a different outlet in the house
*Potentially take the amp to a different house/maybe guitar store
*Swap some preamp tubes around
*Buy a few new preamp tubes and swap those into different positions
*Swap the power tubes around
*Buy a matched set of new power tubes
*Make sure the speaker is connected and not torn etc (obviously this is probably not the issue)
*Plug guitar into input and film that
*Plug guitar into FX return and film that
*Take chassis out and inspect the guts for a bad, loose or disconnected solder joint.

These are in no particular order. The first and third things are what I'd do right now as they are easy enough. Below is a video I made on how to swap preamp tubes. Also make sure all the of the tubes and pushed in real tight and seated correctly. I also highly recommend spraying the tube pins with Dioxit contact and working those pins in and out to clean the sockets. I'm leaning toward a tube issue. Also keep in mind that messing around with the 'guts' of an amp can be potentially lethal as filter capacitors (usually black or blue cans the size of a battery) can hold high voltages even if the amp is unplugged).

Maybe try some of these things and report back. Good luck.