This 5-tube hi-fi amplifier was found in an American publication from 1947; The output is in class B and the circuit uses a source with transformer.
The operational Amplifier used in this circuit is uncommon today. However, the same circuit can be...
This old 1 W audio amplifier transistor circuit is from a 1967 Japanese magazine. The transistors are...
This circuit has a gain of 6 dB for low frequencies from 85 Hz and can be used in a mini...