A tube stage which has the plate connected to the "common" point on the circuit, usually ground This doesn't have to be a physical DC connection, it can be an AC ground, i.e. grounded through a capacitor. This is the most often seen method of making a common plate stage, where the plate is connected directly to the power supply (the AC ground connexion is through the power supply capacitors, which are essentially a short to ground for AC signals). This stage is commonly called a "cathode follower".