1. There is not bias in the grids of 6S33S.
2. An input capacity 6S33S is large, so the plate current of driver tube is necessary to be done more.
3. It is better to do FT3 in 3-4 times more.
Well a few things that come to mind.
First here is a cap on the cathode tail resistor of the phase splitter that shouldn't be there.
Second I should think the 6H30 would do a much better job driving the 6C33 than a 12BH7. I would want a low impedance and lots of current to drive the grids of a 6C33.. I'd even consider an IT in this application.
Third the 6C33 is best run with cathode bias - if you use fixed bias you will need to delay the B+ until the filaments are fully warmed up to prevent arcing. Operating stability is less of a given with fixed bias with this tube, although I prefer fixed bias in general.
The grid resistors are missing on the output stage.
Not really crazy about this design.
First here is a cap on the cathode tail resistor of the phase splitter that shouldn't be there.
Second I should think the 6H30 would do a much better job driving the 6C33 than a 12BH7. I would want a low impedance and lots of current to drive the grids of a 6C33.. I'd even consider an IT in this application.
Third the 6C33 is best run with cathode bias - if you use fixed bias you will need to delay the B+ until the filaments are fully warmed up to prevent arcing. Operating stability is less of a given with fixed bias with this tube, although I prefer fixed bias in general.
The grid resistors are missing on the output stage.
Not really crazy about this design.
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