- "Theres a low-level hum from the output transformer of a SET that I just bought and putting my hand on the transformer with some force eliminates the hum but after a while, the transformer gets quite hot. Before I get one, I want to find out if it will be safe. TIA :) "
I had the same problem with one of the transformers in my ARC REF-3. If I tapped the transformer, the hum would go away. Eventually, the hum wouldn't go away no matter what I did. I ended up buying a new transformer from ARC. They said that that particular transformer "never goes out." The replacement ended the problem.
Frank