We found this circuit in an English publication from the 60's. The transistors are of germanium of the time and the headphones must be high impedance magnetic.
The amplifier shown in figure 2 is based on the MAX9715 integrated circuit from Maxim...
This stage for JFETs was found in a 1965 US publication, but is valid for modern components. |...
This circuit was found in a Japanese publication from 1971. The circuit uses components from the...