6S4S - tube production in the USSR - a powerful triode with directly heated cathode and octal base.

6S4S - tube production in the USSR - a powerful triode with directly heated cathode and octal base. The lamp is designed to enhance low-frequency power to the audio device to the signal generator and low frequency. Is a Soviet copy 6B4G lamp made in USA.

An interesting design feature is the presence of light in a bottle as if the two transistors, the anodes and grids that are connected in parallel, and the filamentary cathode - consistently. Some hams believe that this is not desirable for the lamp used in single-ended amplifiers.

The lamp is very popular among fans of the design of high-quality audio amplifiers.

Old stock. The tubes are new in original boxes and never used. A very rare pairs.

Same date code and made in 1985 year.

Each tube have sticker with actual measurement Ia(mA)

The parameters are measured at Uf = 6.3V, Ua = 250V , Ug1 = -45V

Our tubes are measured by USSR tube tester L3-3

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