This excellent 30 W tube amplifier appeared in the April 1963 Radio Electronics magazine that taught how to assemble it. The critical components in our time are tubes and transformers.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...