This low-power amplifier, but excellent sound quality, uses only two valves and its diagram is obtained from a publication of the 1970's. The critical components, as always, are valves and transformers.
The circuit is suitable for turntables with stereo crystal caps, but can be used for other purposes.
The power supply comes from a 750 V (375 + 375 V) secondary transformer with 100 mA, as well as a secondary low voltage for the valve filaments.
The output transformers are of the type suitable for tubes with a primary impedance of 3 k and secondary according to the loudspeaker, usually 3.2 ohms, in this type of application.
Components subjected to high voltage, such as capacitors, must have working voltages compatible with their function in the circuit.
Figure 1 shows the complete diagram of the amplifier.
