Tube amps and speaker ohms


In your opinion , do push pull amps work better with 8 ohms or 4 ohms. .I am under the impression the lower the ohms, the more power is demanded from the amp....Another question, are there low powered SET amps ,and high power SET amps?
I'm looking at a 40 watt 845 tube amp for my 8 ohm, 89 db speaker.. just cked the Thor has a 86 db W18 midwoofers(2 per cabinet) and a 88 db tweeter. Will an 845 amp rated 40 watts be able to drive the 86/88 db speaker? With authority, bass, mids, highs, in dynamic sound stage? Synergy? Or poor match?
bartokfan
Dear Paul: +++++ " prefer tubes, as to my ear, they achieve the most accurate.....of the recorded material. " +++++

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

Normally the tube is a self harmonic generator ( that does not exist on the original signal/recorded signal ) and normally too due to its high output impedance a tube amplifier is everything you want/like but accurate handling the electrical speaker impedance curve.

Regards and enjoy the music.
Raul.
+++ 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.