The ECC803S is a type of long board ECC83 that is perfect for use in Hi-Fi audio equipment. The long plate construction allows for a higher peak current which is especially useful as a conductive tube.
With the BALANCED / SYMMETRIC option selected, it is a recommended option as a balanced driver stage. The selected MATCHED PAIR option includes the selection for BALANCE and is the recommended option for stereo amplifiers.
Note: Because this tube has a long plate structure, it is susceptible to excessive miking and is therefore not recommended for use in combination amplifiers or high-gain stages. For these amps, the JJ ECC83-S is a better choice.