Tubes vs Solid State - Imaging, Soundstaging, 3D

I did find this dewscription of the difference between noise and distortion.

It would seem to infer that noise is a "random" artifact.

Artifacts resulting from NF would not seem to be random, so I am wondering if that qualifies as noise and can be considered as a factor in a discussion regarding noise floor?

Back on the "life is too short" topic, see This

Paul and Yoko now buddy buddys. "Life is very short...." indeed!

Assuming the noise floor is low and can't be heard anyhow, what is there to hear below it?

Al's comments above are the correct answer to this.

Chaos Theory points to the 'why' of it- the amplifier with feedback is operating in a chaotic fashion where the noise-distortion floor is much higher with a constantly changing non-repetitive signal.

Csontos makes a good point in his post above. IMO this has more to do with feedback and less to do with whether its tube or transistor in theory. In practice though it is much easier to build a zero feedback circuit using tubes than it is with transistors. Ninety-nine and 44/100% of all transistor amps run a considerable amount of feedback, hence the generalization.

For the time being designers have yet to universally recognize the importance of human hearing rules in audio design, so we are likely to see considerable differences in opinion for quite some time :)

In this conversation I've not discussed preamps although I have alluded to them by using the word 'circuit' as opposed to 'amplifier'. The same rules of human hearing of course apply to preamps, and you do deal with the same issues of feedback. However in preamps it is very easy to build a zero feedback circuit with vanishingly low distortion and wide bandwidth, so the argument in favor of feedback weakens considerably, especially in the face of the damage it can do (if you want to build the preamp with opamps though you are kind of stuck- that can only be done with feedback). If the preamp looses information, it really does not matter how good the amp or speakers are- you can't recover lost information downstream.

"For the time being designers have yet to universally recognize the importance of human hearing rules in audio design, so we are likely to see considerable differences in opinion for quite some time :) "

Few things are ever "universally" realized.

Does not make sense to me that such things would be ignored by the experts whose products can benefit.

More likely that different engineers make different judgements regarding what works best to meet specific product goals.

I'm a software engineer. Not much parallel I can think of where a long proven best practice is ignored these days by any good software engineer worth their salt.

Shigeki Yamamoto who is known for his line of SET amplifiers is very adamant about the adverse sonic repercussions of NFB. Even with his DAC design he eschewed OP- amps due to their copious levels of NFB and instead opted to build a discreet analog output circuit free of NFB same as his SET amplifiers. Another example of circuit and not limited to power amplifiers.

I'd like to hear from component designers/builders who believe in the advantages of NFB given its wide use and acceptance. I'm sure they feel ther are sonic benefits or they wouldn't use it. I wonder what's their opinion of the human hearing principle and if they accept the premise.
Charles,