Marshall ECC83S
The Marshall ECC83S Amplifier Lamp is a widespread amplifier lamp that many manufacturers use. The Marshall ECC83S enhancement lamp can also be found under the 12AX7 index, because the ECC83 is European, and 12AX7 is the American symbol for the same lamp. Depending on where your amplifier or the previous set of lamps was purchased for it, there may be one or another notation.