These ECC802S tubes have a NOVAL base and deliver up to 12.6 volts of power. The preamp tubes also offer 150 milliamps of power per each unit that you install into your radio. Their impedance is 10.5 milliamps. Each one of the sockets of the tubes measures 7.4 millimeters, which allows them to fit into a standard 12AU7 or ECC82 circuit. The 12AU7 circuit provides the greatest efficiency for these tubes. Each one of these tubes measures 22.2 millimeters wide by 58.3 millimeters long from the socket to the tip of the glass. This triode style of ECC802S tubes was first made in 1906 for use in early radio capacitors. These capacitors were designed to work as a pair when installed into an amplifier. The technology of the ECC802S tube comes from the additional electrode that is located in the evacuated glass tube between the cathode and the anode. This electrode is responsible for amplifying the signals of all frequencies. This technology also reduces voltage to the grid and directs it toward the tube's plate. The controlling signal at the grid is emitted as voltage, and the signal controlling the plate is current. When listening to music or voices, this means full-bodied bass and low sounds as well as accurate musical instrument reproduction. The noise-cancelling spiral configuration of the filaments in the vacuum tubes eliminates crackling and static sound distortion.This is a genuine vintage tube with the quality that people come to expect from products of its era.  The ECC802S sockets have a wide sound performance with the depth that you need to enjoy your music.