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RE: Thinking about running my non-OTL Circlotron again

"IOW, by 'real class A' you mean class A1."

No, that's not what I mean at all.

In a Class A circuit using linear tubes both halves of the waveform look the same.

"BTW the actual waveforms we get off of an individual triode's cathode differs from the simulation in that it lacks the flat spot at the bottom of the curve unless the amp is driven into clipping."

If each triode is biased at 70ma idle, it can't continue to go down below 70ma. down from idle. (0ma.)

The graph shows exactly that.

For an M-60 to make more than about 5 watts the bottom half of the waveform of each triode will have the "flat spot at the bottom of the curve".

If the tube is idling at 70ma. and it is then driven (by an input sine wave) up to, lets' say 170ma. the top half of the wave form will have a shape and size that represented a 100ma. change to the positive.

The tube in the other bank, at the same time, is being driven by an input signal that is anti phase and that signal will try to drive the tube to a negative 30ma. But there is no such thing. The current in that tube will go down as far as it can and then stay there until the input signal drives it back up.

The "then stay there until" part is the "flat spot at the bottom of the curve".

That half of the wave form cannot have a shape and size that represented a 100ma. change to the negative. A tube cannot flow 30ma. of negative current.


Understand I'm not talking about the output waveform to the speakers.

Edited to say the whole thing again in one sentence.

In any type of tube amplifier, push pull, single ended, Circlotron or whatever...If the positive half of the input signal pushes the tube to more than twice it's idle current the negative half of the input signal will cause a "flat spot at the bottom of the curve".

There is no way around this simple truth.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"


Edits: 08/23/11 08/23/11
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