Mono-Block Tube Amplifier

Mono-Block Tube Amplifier

  • 5 tubes
  • Class AB (‘ish, not quiet class AB, closer to class B)
  • EL34 outputs
  • Approx. 50 Watts RMS output power
  • 10 Hz to 25 KHz -3 dB bandwidth
  • 0.65 % THD
  • Direct grid bias on output tubes

Summary

This mono-block tube amplifier is one of 5 that were developed for the vacuum tube home theater system. It is the same design as is shown in the quad tube amplifier with the exception that it utilizes a smaller power supply. In designing this amplifier i have attempted to squeeze as much power as I can out of a pair of EL34 pentodes while still maintaining high fidelity performance resulting in a bandwidth of 10 Hz to 25 KHz and a THD of 0.65 % while achieving a peak output power of approximately 50 watts RMS.

Mono-Block Tube Amplifier Photos

Photos of the mono-block tube amplifier.
General power amplifier block diagram

Mono-block power amplifier schematic

Mono-block power amplifier power supply schematic

Bode plot of open-loop transfer function before loop compensation circuitry was added.

Bode plot of open-loop transfer function after loop compensation circuitry was added.

Closed-loop transfer function of compensated amplifier.