Self designed tube amp problem

[Helmholtz]

Ok.Is this correct?

While I would have some questions about your full schematic, let's concentrate on the power amp and output power first.

Did you try to inject your test signal to the cathodyne grid via a capacitor? Can you get around 30Vpp at each power tube grid?

[Manowar1985]

It will not be a Cathodyne but a long tailed pair. But when you say 30 V pp you mean between each power tube grid and ground or the floating voltage between the 2 grids.

And no I did not try it should I do that

[Helmholtz]

But when you say 30 V pp you mean between each power tube grid and ground ...

Yes, each PI (whatever PI you use) output should provide that signal voltage wrt ground.

And no I did not try it should I do that

As said.


If you change your circuit, please update the schematic.

[Manowar1985]

Ok thank you I will post the new schematic and take some pictures of the oscilloscope waveforms.

[Manowar1985]

I was just wondering is there any chance this problem is caused by the saturation of the transformer,or generally by a badly designed transformer

[Helmholtz]

I was just wondering is there any chance this problem is caused by the saturation of the transformer,or generally by a badly designed transformer

Transformer saturation does not cause clipping.

Please post a scope picture of the distorted output, making sure that each EL84 grid gets clean 30Vpp.

[vintagekiki]

I was just wondering is there any chance this problem is caused by the saturation of the transformer,or generally by a badly designed transformer

Only poor quality rewound transformer can be a badly designed (thinner wire, poor calculation ...), the original transformer no.
Have you checked the filtration +HV. Does, and how much the voltage drop on the first ELCO, at the beginning clipping of the output signal at load.

[Manowar1985]

Helmholtz thanks. In short what does saturation cause
vintagekiki I will check the filtration

[Helmholtz]

In short what does saturation cause

OT saturation causes signal distortion but doesn't limit the peaks. Looks a bit like crossover distortion but not exactly.
Just show me the pictures.

[Manowar1985]

Thank you very much.I will say once more.
The information you people provide is very valuable. I have learned stuff in half a month that I would not have learned in a year maybe. Thanks again.