How far have ss amps really come in the last twenty years?

I may be missing something (point it out to me), but there’s almost no convincing evidence out there to support repeatably audible differences between high quality cables or amps

The differences have to do with distortion. This is easy to measure, and when measurement correlates with subjective experience then we can call it real. Its well-known that IMD is highly audible. It should then come as no surprise that when adding capacitance to a power supply reduces IMD (due to less modulation of the power supply- this is a simple timing constant in most cases so this is easy to quantify) that you can also hear it.

The higher ordered harmonics have long been known to contribute to brightness and harshness. We’ve known this since the 1930s (see Radiotron Designer’s Handbook volume 3, IIRC page 67). Now days we also know more about how the masking principle of the human ear works. This applies directly to how distortion is audible, since the ear converts all forms of distortion into some sort of tonality. In tube amps, a 2nd or 3rd harmonic dominates (depending on if the amp is single-ended or fully differential). The ear treats both the same. Now tube amps make more distortion than transistor amps, but those lower ordered harmonics are crucial as they allow the ear to mask the presence of the higher ordered harmonics. This is why tubes sound smoother on top; its nothing to do with bandwidth- we can’t hear the higher orders! The funny thing is, its been shown that injection of a 2nd or 3rd order also allows the ear to perceive more detail and greater depth- thus accounting for why tube amps tend to be smoother, more detailed and with greater soundstage. The peculiarity is that this actually makes tubes more accurate! I’m very convinced that we need to do more research to find out why this is so, but if you are pragmatic, you don’t need to know why, just do engineering based on the implications:


Now its accepted that we can’t build amps that make no distortion whatsoever and that is what is needed to get around this issue. So instead, it appears that if a circuit is devised that injects a 2nd or 3rd harmonic **of appropriate level** that we can build a more neutral sounding amp. Of course, this sort of thing is readily audible even in a DBX test; but IME people doing such tests will avoid allowing good examples of such to taint their ’findings’. You can’t do it if the test is rigged! You have to start wtih two amps that are based on different design goals rather than two that are built the same way. What I mean by this is, you can use engineering to design an amplifier with low impedance and low distortion, or you can use engineering to build an amplifier that sound neutral according to human hearing perceptual rules. One is the Emperor’s New Clothes, as its designed to essentially look good on paper, and the other is real as its meant to work with rather than against the way we perceive sound. Naturally the latter will measure ’poorly’ compared to the former, but the latter is far more likely to sound real.


If you compare two such amps as in my example above, even in a DBX you can perceive the difference. I’ve seen it/heard it.


One more thing as a sort of BTW... none of this implies tubes or solid state. Its all engineering. To me it just makes more sense to design a circuit based on human hearing perceptual rules than making a nice piece of paper! This is the very reason why tubes are still around, decades on after being ’declared obsolete’. The audio industry in general really hasn’t tackled this issue at all, preferring to keep their collective heads in the sand rather than deal with physiological knowledge gained in the last half century. Pathetic, when you think about it. We really shouldn’t be having a tubes/transistor debate this far on.

Teo, I had a couple of Yamaha B2s in my time ( and a Sony vfet integrated ), and I really enjoyed them. They did not last as long for me as I would have liked, as they developed problems after long time ownership. Repair was nearly impossible to get done, for whatever the reasons ( unavailable parts supply if I remember ). I handled them with care since new, and never over taxed them. They just failed. Sold them for parts.... Atmosphere, I do not see much debating about tubes / transistors as much today. Much more debating about Class D, power cables, passive vs. active, and occasionally speakers ( horns, panels, boxes ). There seems to be an acceptance of both, imo, and that the camps of tubes and transistors have come to a stalemate. just from my readings here, and elsewhere. However, as a manufacturer of tube gear, you obviously are seeing the debate continue. My best. Enjoy ! MrD.

@mrdecibel  Its on this thread too:

No, in my limited experience, I often don't hear the difference between amplifiers (with the exception of underpowered or tube-bloated amps)

The comment is ridiculous, but one that is common in this debate, as if, somehow, hearing how tubes do things is an exception to this DBX nonsense.  The thing is, its become so ubiquitous that we don't even see it sometimes. The thing is, tubes get docked for having a higher output impedance and thus causing a frequency response error (which is often true, but also often very slight) while at the same time no-one says anything about the colorations caused by distortion. Brightness and harshness, ubiquitous to solid state, is indeed a coloration. But we just accept that this is so, and somehow its the norm. But if you listen to real music, that brightness and harshness at volume isn't there and a good tube based system doesn't have it either.


What I am saying in all this is if we collectively did our engineering homework, we could have solid state that doesn't sound harsh in any way. But, we don't, so the beat goes on.

MrDecibel...you said exactly this, "You stated you were in a band, so I believe your ears are shot, and unfortunately, you probably did not use ear protection." That's the comment I was referring to...and I also know different amps obviously sound different or I'd have no preferences...that would be boring...I can say that great amps get music to the speakers  in ways that can be tonally similar, but talk to any reasonably experienced electric guitar player and you can get the drift that all guitar amps are different, even among the same versions! I like the recent discussions about Nelson Pass researching (and atmasphere's further explaining) and implementing the adding of even ordered distortions into a circuit, as maybe that narrows the gap between a great tube amp's "musical" tone and that of well measuring SS amps, some of which also do a good job...my tube amps are a revelation of tonal "correctness," even to my recently cleaned old ears.

Mr decibel,

the problem with those two designs, is that they were only partially V-fet, as the transistors were not available to make them fully v-fet.

thus.. the chain of signal manipulation and amplification was inherently non-linear in gain, even though the V-fets in situ, were linear gain.

the whole chain must be linear gain v-fet, otherwise it will be colored enough that it is notably more difficult to discern what good the v-fets were bringing to the table.

Of the two, the Yammie was probably the better unit, as it had some middling sized v-fets in the driver stage, IIRC... and then the output stage was all v-fet.

Only ONE Sony unit had a second and singular ’small signal’ V-fet in it other than the final output transistor stage, and that is the Sony TA-5650 integrated amp. It had a set in the phono section.