The scenario
Designing a single-ended tube amplifier using the classic 2A3 power triode, suitable for driving efficient speakers. The schematic includes a 6SN7 input/driver stage RC-coupled to the output stage, with a full-wave bridge rectifier and choke-filtered power supply.
What is in this drawing
Read the decisions behind it.
01
Use a bridge rectifier with center-tapped transformer to provide full-wave rectification
02
Directly heated cathode biasing with a bypassed cathode resistor for stable operating point
03
RC coupling between stages for simplicity and reliable DC blocking
This minimal circuit topology can be reused for any directly-heated triode (e.g., 45, 300B) by adjusting bias and load values.
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