We found this audio preamplifier circuit with a 741 operational in a 1976 publication. However, with the upgrade of the components it can still be assembled today. Circuit characteristics are next to the diagram. The power supply must be symmetrical. Other operational amplifiers can be experienced. C1, 2.2 µF, can be altered to modify the circuit. Consumption is very low and the inputs have the following characteristics:
E1 - 5 mV input and 500 mV output with RIAA equalization
E2- 100 mV input impedance of 100k to output 220 mV
