ARC REF2 5AR4 arcing on warmup

I feel lucky that the one I recently bought has no such problem. From a tech here who has a lot of experience on ARC equipment: most of the time a problem with tube equipment can be traced back to a bad tube.

I would bet your replacement tube is faulty.

About a year and half ago I turned off my Ref2 MkII and turn back on in just a couple seconds. I heard a funny arcing noise and could see the 5AR4 tube going into spasims. I would describe it as a medium arcing event, but...

It made a fuss right after after turn on a couple more times soon after that. At first I figured it might be toast, but the issue went away. Have not noticed anything for a least a year of frequent use.

Hope yours does the same.

I've never called ARC but many people have posts saying they are very helpful - if it continues.

TD