Circuit Project Electronic

This is the schematic diagram of the “Li’l 4×4’s” main amplifier circuitry. This completes the circuit if you’re only interested in line-level input sensitivity.
The first big difference in this design is that the output stage is fixed-biased rather than cathode-biased. This gives excellent control over the bias point, and also does not “rob” any range [...]

The unit is powered directly from the 120 volt AC line, with no power transformers. Filaments are wired in series, with the total adding up to 117 volts (35 + 35 + 35 + 12). The 35W4 forms a half-wave rectifier, which is filtered by a three-stage RC network. The B+ for the output stage [...]