This amplifier was found in a tube equipment manual from 1947. The high-fidelity circuit has pentode tubes at the output and a source with transformer.
This circuit with the NE602 was found in the February 1997 Electronics Now magazine. The NE602...
We found this circuit in Radio Electronics magazine from September 1959. The circuit has different...
Found in a 90s Radio Electronics, this circuit uses an AD590 or AD592 for remote temperature...