Tubes vs. solid state.

It sounds pretty fascinating. Can you reference any papers available online?

Of course, as you well know, the math only takes you so far because our knowledge of the ear/brain system is so limited. For example, who would have thought that upper-order harmonics are so much more objectionable than lower-order? I suppose you could argue that it makes sense that the harmonics closer the fundamental are going to be less objectionable, but I don't believe there's any theory that would have predicted the extent to which the brain objects to high-order HD. Same with stuff like timing of reflections, etc. It's just the way the brain (and to some extent the ear) works. Right?

A little more fuel on the fire......

"A few music listeners still have the illusion that...tubed units are in some mysterious way better than present solid-state units. The overall superior performance of solid-state design has been scientifically proven...Anyone investing in a contemporary vacuum tube product will experience less than the best available performance."
source: McIntosh press release/TAS

"Had I performed a blind A/B listening test, I would have picked the tube amp as being solid-state, and the solid-state unit as being tubed."
source: Sam Tellig/Stereophile

"When it comes to tubes, you will only find solid-state in my personal system....and I manufacture some very good tube gear!"
source: High end audio manufacturer in Minnesota(no names, please)

Paulfolbrecht, yes, General Electric proved that humans use the 5th 7th and 9th harmonics as a means to determine the volume of a sound back in the mid-60s.

So how this relates to the TvsSS debate: The issue centers around feedback- by adding feedback to a tube amp you can make it sound 'solid state' on account of the chaotic harmonic noise floor. I believe the sound of 'solid state' is not so much that of transistors, rather that of a transistor amplifier that has a lot of feedback. Nelson Pass is a good example of someone making transistor amps that don't sound 'solid state'. Many of his designs use no feedback.

For decades, triodes have been known as the most linear form of amplification (at least as far as the specs of triodes appear on paper). The trick it to use the triodes in a way that they will not make distortion **without** also using feedback. IMO/IME this is the primary advantage of tubes- that you can do such a thing in a way that to me seems easier than with transistors.

People such as Nelson Pass are eroding that advantage; I think ultimately though that too few designers are trying to figure out how to crack the nut without feedback. We now know from Norman Crowhurst (55 years ago), General Electric (45 years ago) and the proofs of Chaos Theory (mid 80s to present) that feedback simply does not work- and won't until an amplifier without a propagation delay is somehow devised.

Olesonmd's examples bear this out- the amplifiers used in his examples all use feedback and so have more errors in common with each other and less in common with real music, regardless of being tube or transistor.

Anyone who claims that the "overall superior performance" of solid-state has been "scientifically proven" has no understanding of the real issues.

I guess it was proven in the 70s when we had those wonderful solid-state amplifiers with their amazing THD measurements.

A-S, of course I pretty much agree with your thoughts. (And I do not have your engineering knowledge.)

I think most agree Pass amps sound great but not really like [very good] tube amps.. dimensionality does seem to be a bit flatter for one thing. Of course they have advantages too. It is just a different sound - one with no real weaknesses I would say.

There are quite a few SS amps now that manage to avoid nearly everything in the telltale SS signature.