6SL7 SRPP / 2A3 Single-Ended Tube Amp Schematic
2A3 Single-Ended Loftin-White / Shunt Regulated Driver. Output: 3.5W @ 2.5% THD. OPT: 2.5-3k
Very simple and elegant little triode amplifier. The direct-coupled (no coupling capacitors) two stage circuit was designed as a laboratory amplifier in the 1930's but the team of Loftin and White.
There are a couple items of interest with this circuit.
- The bias for the output tube is provided by the voltage divider created between the driver stage load (upper half of 6SL7), the driver stage (lower half of 6SL7) and the extra large cathode resistor (the three series resistors below the 2A3 tube).
- How high gain, wide bandwidth, and low source impedance are achieved with an absolute minimum of parts with the SRPP front end.
6SL7 SRPP / 2A3 Loftin-White Tube Amplifier Schematic