06-23-2017, 11:34 AM
Anything that is capacitive or inductive and where vibration can change the characteristics enough for it to become noticeable due to the sound propagation whether through air or through chassis can create microphonic effect. Tubes have large electrodes on flexible enough support that they could experience oscillation; so do the tuning caps.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.