Mono-Block Tube Power Amplifier

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.

Publications

• 'Keep Those Filaments Lit, Design Your Own Vacuum Tube Audio Equipment.' Hackaday, June 4, 2014.

• G. L. Charvat, “Vacuum tube home theater system (part 2), vacuum tube power amps for home theater,” Audio Express Magazine, June 2012.

• Make Magazine Blog, ‘How to design a  vacuum tube amplifier.’

• G. L. Charvat.  “Design and fabrication of high-fidelity vacuum tube audio-frequency power amplifiers,”  MIT Haystack Observatory, February 3, 2010.

Engineering Notes, Schematics, and Plots

Caution!  High voltage.  Do not attempt to build anything shown here unless you have taken proper high voltage training.  The high voltages present in these tube designs are deadly.

Mono-block amplifier design notes

Biasing notes for all of the various power amplifiers (including the Quad-40 as well as the monoblock amp).

Bode plot analysis & feedback loop compensator design notes.

Bode plot data, %THD, & peak-power data.

MATLAB script with Bode plots (before & after loop compensation) & loop compensation network calculations for the mono-block amplifier.