This 6W amplifier with 4 tubes was indicated in an American documentation from 1947 to operate with recorders. The circuit uses a source with a transformer.
This circuit with the 741 operational amplifier was found in the March 1995 issue of Electronics Now...
This circuit was found in a General Electric documentation from 1966. It uses discrete components...
We found this circuit in a French technical documentation from 1982. The circuit can be...