Class A hybrid tube-SS openloop power amplifier

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Class A hybrid tube-SS openloop power amplifier

How about to try a “less serious” design 🙂. It would have some excellent parameters, like bandwidth, dynamic range, low noise, free of crossover distortion, and some less good parameters, like non-linear distortion, which would however remain low-order only.

The concept is well known, a tube gain stage followed by a class A solid state output stage, with gain close to +1, no global feedback from output to input, and very low distortion (speaking about output stage). No race for the best possible parameters, however avoiding known issues like crossover distortion, noisy circuits etc.

I think I have all the building blocks prepared. Is it worth trying, what do you think?

I am not sure if this belongs to Solid State or Tube forum, so if mods would decide to move it, please feel free to do so.
 
I would build them as separetes.

Start with prepamp and test on whatever then do power amp.
I did exactly that and learned a lot along the way.

The Sziklai type schematic here is what ended up sounding the best. You can use 6N1P and simply adjust the heater circuit.


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This is how it looks on a test bench. On the top there is a tube gain stage, below is a class A SS buffer, parameters as this one:

PM-A4 power amplifier
 

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It would have some excellent parameters, like bandwidth, dynamic range, low noise, free of crossover distortion, and some less good parameters, like non-linear distortion, which would however remain low-order only.
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Is it worth trying, what do you think?

Of course it is worth trying.
But to get low non-linear distortion and low output impedance (to have great dynamic range) it would help with some feedback, global or local.
 
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