[sfox7076]

Recently, after I power down the ultimate 70, there is a clicking sort of like the mute circuit turning on and off a few times rapidly.  What would cause this?

[avahifi]

This sounds like some kind of thermal action, something exhibiting movement caused by the previous heating of that element cooling down, letting the part move slightly.

It is most likely an internal part in a vacuum tube as they run by far the hottest in the unit.  See if you can localize the issue the next time you shut the amp off.

Frank

[sfox7076]

Will do.  Thanks Frank.  And happy Bday...  Well, I will be sad if my Mullards EL34s are done.  I will be better if it is just the rectifier.  I still have the stock ones, so maybe I will swap those in and see if the problem persists.