Here I present a simple one-valve involvement stereo preamplifier with dual triode vacuum tube. Any twin triode with separate cathodes designed for amplifying audio signals can be used, such as: 6CC41, ECC82, ECC83, ECC802S, ECC803S or 6CC10. Heater winding should be chosen for a particular typeof tube. If the heating filament coil gives a little more voltage than is needed, it can be reduced using resistor. This kind of supply is also more friendly to the tube, it will not suffer such a large inrush after switching on. Anode winding should have a voltage 30 - 50V. Doubler is used, because a lower voltage transformers are more accessible. The resulting anode voltage will be approximately 80 - 130V. Improved power supply filtration is assured by pi filter. If even there was a hum, you can add one more filtration step (Another 4k7 resistor and 47u capacitor).