Tube amps and speaker ohms

+++ Please could you explain how the tube technology can be " accurate " to the recording +++

Sure Raul. Perception of music and the accuracy thereof is 100% subjective. To my ear no amplification device on the planet can come as close to a real piano recital as a SET amplifier.

+++ Normally the tube is a self harmonic generator +++

That is not true. Always the tube and the transistor are self harmonic generators. Transistor generally being much worse, up 70% THD. Amplifiers by design compensate to correct these flaws. My ear prefer vacuum tube solution – for now.

Yes, tube amplifier require much more careful speaker matching as they have much higher output impedance than a transistor amplifier. People who do not understand this better stick with transistor amplification.

Regards
Paul

Normally the tube is a self harmonic generator ( that does not exist on the original signal/recorded signal )

Raul, I would have thought you would have educated yourself better before making such an obviously false statement! You are in a lot more trouble with transistors in this area then you ever would be with tubes! Look how many tube amps can actually operate with low distortion with zero feedback, and then count how many transistor amps that do the same thing. The zero feedback transistor amps are *sorely* outnumbered!

If we run feedback on our amps, which are OTL, we can get the THD down to 0.001% at full power, but who'd want to (just like frying an egg on the sidewalk)? It is true that you reduce a lot of distortion that the ear does not care about, but you increase the distortion that the ear *DOES* care about!

Ultimately it is the rules of human hearing that are the most important factors in audio...

The zero feedback transistor amps are *sorely* outnumbered!

How do you stabilise a transistor amp circuit without any feedback at all, anywhere?

Hi Gregm, you might ask Nelson Pass or Charlie Hanson of Ayre, both of whom make zero feedback designs.

FWIW, negative feedback is a *destabilizing* feature in amplifier design, not a stabilizing one. This is a common misconception about feedback.

Direct-coupled transistor amplifiers tend to use feedback as part of their means to control DC Offset at the output- IMO an inappropriate use of feedback, as it requires a greater amount of it to do the job. It may be the traditional way to do it, but in the world of high end audio, 'traditional' is a weak excuse for a solution to a problem.

Thank you, Atma -- good point about Mr Pass or Mr Hanson.
I should have worded my question better, anyway!