This project was obtained from a 1974 publication, consisting of a small 3-valve amplifier that provides approximately 3 W of power with excellent sound quality.
The critical components, besides the tubes, are the transformers. The output transformer is of the low-power type simple for the EL84 (6BQ5) tube while the supply transformer has a 15 + 125V secondary with 40 mA or more.
The source's electrolytic capacitors must have working voltages of 200 V or more.
The input impedance is approximately 1 M ohm. In figure 1 we have the complete diagram of the amplifier.
Figure 1 - Full diagram of the 3 W amplifier.
