A Good Pentode Push-Pull Amplifier

[Cressy Snr]

Here are the schematics for the final version of the pentode push pull amp I have been developing over the past few years.
A long story but the results are rather good.

Audio Circuit:


Power Supplies:

[Cressy Snr]

Just a small comment on the power supply. It is not essential to emloy Morgan Jones Statistical Regulators on the power stage screen grids. Simple Zener string shunts could be used for very little a drop-off in performance, and I have changed the schematic to reflect this.
The excellent noise performance of the statistical reg gives the biggest performance boost when employed to regulate the input stage pentode screens. Statistical regulation of the output stage screens could be a teensy bit overkill; depends how far you want to take things. I'm not saying don't use them, but......

A nice little series tube regulator is a good way to keep the output stage screens locked down, but I haven't tried that on this project. Something like a 6EM7 dissimilar triode with the hi-mu unit as the error amp, might be good.

[jack]

I would agree with you on that. They are best in small-signal environments e.g. front-end, pre-amps and line stages... places where the s/n ratio is critical.