Every vacuum tube has at least two terminals for conducting
electrons. The "cathode" emits electrons and the "anode" collects them.
The cathode is heated to such a high temperature that
electrons in its coating (often an alkaline earth-metal oxide)
gain enough energy to break away from the coating.
This "thermionic emission" creates a red glow. Eventually, a cloud of electrons (negative charge)
in the space around the cathode. The tube is then standing
by, ready to go to work.
When you switch the amp out of Standby mode, you are connecting a positive
called B+) to the tube's anode, or "plate".
positively charged plate attracts the emitted electrons and uses the
electric current to power your speakers,
Electrons continue to move into the cathode's oxide coating, maintaining