Tapping your thumbnail? Why don't you tap your cartridge or lick a hot tube?
Play the amp normally and see if it echoes or picks up too much noise.
Play the amp normally and see if it echoes or picks up too much noise.
Sophia Electric tube quality
I wonder if others have experienced poor quality with the Royal Princess 300b tubes. Purchased a new pair and one shorted out in a couple of months in their amp. Sophia replaced it and the new pair were extremely microphonic -- rang like bells when tapped with just my thumbnail. Sophia's response to my complaint was, "Stop tapping the tubes.