When I read this thread title; "Tubes vs. Solid State Amps", I recalled hearing that solid state adds odd-order-harmonics to the signal which are unnatural and cause listener fatigue, but importantly, solid state is considered more "accurate". I even found a write up https://blog.Thetubestore.com/tube-vs-solid-state-why-do-tubes-sound-better
, which repeated what I had heard, just to make sure my old memory was correct.
Valves supposedly give even order harmonics, as do real musical instruments, which according to the link above, "make sound fuller, like a choir", but according to the link above, less accurate? Ayon advertises "no solid state in the signal path" as a selling point for their Spitfire Class A SET (which helped convince me to buy one). But whether or not there is solid state in the signal path of Ayon amplification, is the reason for avoiding it because it causes odd order harmonics and listener fatigue true?
Single-ended circuits, tube or solid-state, are typically dominated by second harmonic distortion but include even-and odd-order harmonics. Differential ("balanced", though not quite the same thing in reality) circuits cancel even-order harmonics by design so odd-order harmonics dominate. You can make single-ended SS amps but most tend to use differential circuits so have lower even-order harmonics.
SS devices, and amps, tend to have high intrinsic gain and bandwidth allowing for more feedback to further reduce distortion. Feedback also stabilizes the operating point so the amp has less "drift" with time, temperature, and so forth. High feedback is not bad, but must be properly designed. The arguments against feedback I have seen are based upon decades-old circuits long outdated or poor execution of modern designs. To achieve high feedback you need high bandwidth and high gain "inside" the amp to maintain high performance across the audio band. Fail at that, and higher harmonics start to become a problem as feedback rolls off at high frequencies due to limited internal gain-bandwidth. Tubes usually have lower gain and thus lower feedback, resulting in higher distortion but dominated by lower order stuff and without the relative rise in relative HF harmonic level some (many? most? I don't know) SS amps.
Any distortion means the sound is less accurate to the source. We are talking about playback here, recreation not creation of music, so in my mind the goal is to not add anything to the original unless I want to add it per my preference. And note real instruments have all sorts of harmonic spectra, certainly not just even. Some are near pure tones (flute), but most have a complex mix of harmonics, some dominated by odd, some by even, and many a mixture of both.
Listener fatigue can be many things, from just listening too loudly to clipping the amps and causing lots of distortion. A clipped tube amp can be just as fatiguing as a clipped SS amp, though before hard clipping the tube amp will usually exhibited "softer" saturation with distortion rising more slowly before clipping. For a number of reasons SS amps tend to move very quickly from clean sound into hard clipping when overdriven. The counter is that it is usually easier to get a lot more power from a SS amp so hopefully clipping is less likely.
Same question regarding: keeping the signal path as short as possible, class A operation, SET's, low capacitance highly purity wire (silver/copper), star grounding?
I do not know what this means. Fewer active devices means potentially less noise and distortion, but an additional stage can often provide greater gain-bandwidth and better drive the load for better performance. A single-stage amplifier will generally work with a limited range of speakers and provide limited dynamic range since you can only get so much gain and power from a single stage. Horns and highly-sensitive speakers are thus popular matches to SET amplifiers.
From an engineering point of there is insignificant difference between copper and silver conductors particularly at audio frequencies. Low capacitance matters if the source and load impedance are very high; in practice the only place that occurs in a typical system is from the phono cartridge to the preamp. Or if the runs are extremely long, much longer than in a typical listening room.
Mostly questions such as that posed on this thread "Tubes vs Solid State Amps" get opinions on specific pieces of equipment that people believe in, but I have also on similar threads seen arguments blow up about choices viewers have that do not mention or focus on whether the devices being argued over are tube or solid state but which, I suspect, should.
Tube vs. solid state arguments IMO must include the system in which they are used and listener's preference. You can make a SS amp tube-like and vice-versa; designing for a particular sound is a choice during development.
In my uneducated opinion based only upon what I have read and seen on this forum, it seems that those who favour solid state (and digital) tend to gauge performance by measurements (on solid state instruments), and those who favour hollow state, especially short signal path, class A SET's, gauge performance on sound, but what do I know.
I strongly disagree with that assumption. While by most measurements digital and SS devices outperform their tube counterparts, the idea that somehow their advocates do not care about sound is an old, tired, and divisive argument. As an engineer I have long been targeted as "anti-music" or "anti-sound" simply because I value measurements and such, ignoring the facts that I love to listen to music and use that to "turn off" the analytical part, and in fact play (make) music myself at a reasonably high level. Many audiophiles prefer SS amps for their tight bass and clean sound because it enhances their enjoyment of the music, not because it looks better on some graph. And in my decades fooling around with all things audio there have been plenty of "tweakers" using all sorts of equipment (tube and SS) who fit another tired old cliché that "audiophiles listen to the gear, musicians listen to the music".
My system is all SS now, but I have held on to some of my old tube gear, and for some time ran a hybrid system I was quite happy with. People listen to what they prefer, irrespective of what the spec sheet says or what active devices are inside.
Could someone enlighten me?
Alas, probably not, prejudice is very hard to overcome. Grouping all SS folk into "focused on measurements" vs. "focused on sound" is a very wide brush and IME/IMO a disservice to many audiophiles who prefer SS. That said, in most any SS vs. tube (analog vs. digital, etc.) debate, measurements and such are sure to come out. I think the SS people arguing their preference tend to drag out the measurements to beat down the other side, whilst tube aficionados lacking objective superiority resort to subjective preferences in sonic character. Both sides ignore the fundamental bond we all have in wanting to hear the best sound we can. How we get there should not really matter... But humans always seem to have a need to convince others that they are (and/or their way is) best. I am no different than any other in that respect.
IMO - Don