Q: Why do tube amps, mics, and other gear need to warm up before you use them?
A: An excellent question, and one that we sort of answered in another context before. Here’s the pertinent quote, which came via tube expert Steve Wilson:
“A vacuum tube operates on the principle of thermionic emission. When metal is heated, it gives off or ’emits’ the electrons that have been deposited as a coating on the tube’s cathode during the manufacturing process. Preheating a tube can extend useful tube life by making the emission more uniform. This keeps the electron stream more even, reducing hot spots, thus promoting a longer useful life.”