New Tubes then a loud Hum!?

I replaced the output tubes with vintage good tubes and preamp tubes with all new ones.

As soon as I switched the standby on I got a Loud Hum or short that sounded kinda like an unplugged guitar jack that was shorted.

This noise was not affected by any changes to the amp controls and so I immediately switched it off and made adjustments while in standby and continued to troubleshoot.

I gave up and the next morning it was gone.

Any suggestions?

Also: I have a ringing when playing. I think that is a "micro phonic" preamp tube, so I will start the swapping procedure to move that tube to a less sensitive spot in the chain.

All suggestions are appreciated and thanks for reading.

Excessive humming can definitely be the sign of a bad tube, and the ringing definitely sounds like something is microphonic. Try the old pencil eraser trick: With the amp powered up and in play mode, gently tap each tube with the eraser. If one causes ringing, it is likely microphonic and should be replaced.

The ringing is most likely a preamp tube,check as described.Anytime you get noise that is not affected by the controls,it is from the output section,the controls are all in the preamp.You say you "replaced the output tubes with vintage good tubes".Are you sure they are matched and in the proper bias range?Tubes that are too far out of "match" can cause hum.Tubes that are biased too hot will cause a loud hum as well.

The tubes are correct, as I got them from Mesa for the amp specifically.

I rolled them years ago and saved them for spares.

The hum is gone and has not returned.

Thanks all.

I will post results from my findings.

Left this one hanging...really sorry.

It was a bad preamp tube.

Replaced and no more problems.