The plans for this five-tube superhet, dubbed the “High Fidelity Five,” appeared in Popular Mechanics 75 years ago this month, October 1940. It got this name due to its tone control circuit, which enabled the “small set to have a bass response comparable to that of a large receiver,” since the circuit could amplify the lower tones without distortion. The set also featured mechanical pushbutton tuning, with a tuning assembly that was commercially available. The project was not designed for beginners, but was “quite simple and well within the building range of the average experimenter.” Cabinet details were given, but the article mentioned that suitable cabinets were available for purchase.
The set had a transformer for both the B+ and filament voltages, and employed a electro-dynamic speaker, with the field coil also serving to filter the output of the power supply. While the full schematic and pictorial diagrams were given in the article, blueprints were also available for purchase.