Can tube preamps be as 'detailed' sounding as ss?

The quick answer is 'yes'.

The more complex answer is that transistor preamps might sound more detailed at first blush due to the presence of odd-ordered harmonic content (at low level) which serves as a loudness cue in the mids and highs. This causes them to seem more detailed, but a good tube preamp will have actually more detail yet be laid-back at the same time.

IOW some audiophiles equate brightness and detail unconsiously- when odd-orderd distortion is what they are really talking about (this is where the term 'clinical' comes from). Often the word 'dynamics' is used to describe odd-ordered harmonic distortion too.

Zaikesman, I agree that topology has much to do with performance- that it is not just tubes/ss. There is a bit of a strawman going on in your post though, as I was commenting on the fact that audiophiles often interpret brightness as detail (although they don't always like it, thus the term 'clinical').

I admire Nelson Pass's designs as an example of the sort of work that is actually advancing semiconductor-based amplifier technology, and I've been watching the class D stuff evolve for several years too. I am also a big believer in price perfomance curves and their significance.

The bottom line is that I believe what I preach and I try to practice it to the best of my ability. In this way I stand behind my word. I hope you are not taking me to task for that, but if so I have no worries -its not as if I've been trying to hide anything- after all my moniker is atmasphere :)

Zaikesman, I appreciate that you have a level headed attitude towards the sport. If you look back at my original post, you will find in the second paragraph the acronym 'IOW', which is to say that I was indeed commenting on the fact that many audiophiles accept brightness in lieu of detail.

I have a customer now that is objecting to the idea of a 'detailed' preamp, on account of he does not like brightness. So I am commenting on a very real phenomena (although I don't think you were objecting to that in my post).

I do think you were objecting to my initial assertion that many ss preamps get identified as detailed because the high/odd-ordered harmonics that they make (in very small amounts) are interpreted by human ears as loudness cues. This does happen to be a fact, as the human ear uses the higher (+9th - +17th) odd orders to tell how loud a sound is.

One time (30 years ago) I was servicing a transistor amplifier and had it on the bench VU meter. I noticed that when the amp was distorting heavily (malfunctioning), the -30db signal that it struggled to make sounded louder than the 0 VU signal it made when it worked correctly. I later found out that General Electric had proven in the 1960s the human senstivity to the harmonics just mentioned. Oddly, many audiophiles are not aware of this study!

IOW means 'in other words'.

The 'citation' I've been referring to is the study by General Electric that was done back in the 1960s. In it, they found that people will tolerate quite a bit of even-ordered harmonics added (up to 40%), but were not tolerent at all of odd orders, objecting to vanishingly small levels. The study showed that the human ear uses odd ordered harmonics as the primary means for determing loudness.

What this means for audio design is that designing with an eye to remove this harmonic content (+9th odd orders) will result in a more relaxed presentation.

If you want to see how this works in the tubes vs transistor thing, all you would have to do is run a sine wave into a preamp, run it up to clipping and view the output with a scope- the tube unit will have a rounded waveform at clipping, the transistor unit will look on a scope like somebody cut off the top of the waveform with a scissors. This 'cut off' area is a place where odd ordered harmonics abound.

Semiconductors, even FETs, by their very nature tend to generate these harmonics more than tubes, even if not being overloaded. It is something that comes with the territory in things solid state.

Sean, tubes *are* as fast as transistors, else vacuum-tube radio circuits could not exist. There are many things that limit bandwidth in tube *designs*, but tubes are not the culprit (check out the risetimes on our website sometime). Soft clipping is caused by space charge effects (a cloud of electrons that occurs near the plate of the tube) which is a phenomena of a tube near saturation. It has nothing to do with bandwidth.

Eldartford, there are transistor amps now that have a 'soft clipping' feature, but clipping distortion is a gross manifestation of the effects that I am referring to. Unfortunately these 'soft clipping' amps still retain the transistor/odd-ordered harmonic signature that the ear detects so easily. This is my own opinion, but I feel this issue of higher/odd ordered harmonics is one of the more important issues that seperates the subjectivists from the objectivists.