Audio advancement - why?

Milpai, as humans we hear in a very specific way- there are certain types of distortions that our ears don't care a lot about and there are other distortions that our ears care *a lot* about.

For example, we used the presence of odd-ordered harmonics, specifically the 5th, 7th and 9th as a means to determine how loud a sound is. This is arguably one of the most important rules of human hearing as being able to tell how loud a sound is is the sort of thing that can say whether you live or die!

It happens that tubes can make less of these harmonics than transistors usually can. There are exceptions (although they are few). To do this one would have to avoid the use of global negative feedback as a design element regardless of the circuit being tube or transistor. This is a lot harder to do with transistors (since they are not as linear) than it is with tubes (triodes are the most linear form of amplifying device known).

It turns out that global negative feedback, which is normally used to great success in reducing overall distortion (THD) actually enhances, to a very small degree, the odd-ordered harmonics that I mentioned before. Our ears are extrememly sensitive to this enhancement; 100th of a percent is easily audible and audiophiles have terms for this that you have heard before: sheen, hard, harsh, brittle, clinical, etc., all expressions of a very small amount of odd-ordered harmonic enhancement.

You state: "Is it because people like the tube distortions over SS?". Yes, that's probably it. The characteristics of tubes are pleasing to the ear. However, I would suggest that it is only some people who like tubes over solid state, or else everybody would use tubes. Aromatic hydrocarbons are pleasing to the nose, but I don't suggest you sniff gasoline. Fat is pleasing to taste, but I don't suggest you live only on jelly filled donuts. Tubes sound good, but I wouldn't suggest you listen only to tubes. It won't kill you like the gas or the fat, but like the gas or the fat, it has disadvantages as well as advantages. So choose the one you like and enjoy the music.

I just finished a terrific book dealing with the human brain and music called "This is Your Brain on Music" by Dr. Daniel J. Levitin.

A bit technical in spots but highly recommended reading nonetheless.

Available in paperback.

I guess we have developed hearing into a finely refined sense and listening into a finely refined hobby where we are willing to compromise certain performance attributes for the sake of enjoyment. In the other applications you mention, like computing, the attributes we value can be delivered more quickly and cost effectively using ss. I personally love the sound of tubes, the sound is more natural and beautiful to my ears.

In case it was not clear, the point of my prior post is the fact that tubes happen to obey the rules of human hearing to a much greater degree than transistors do, hence the reason why it is so much easier to make a musical sounding tube amplifier than it is to do the same with solid state.

If you look at it from the perspective of rules of human hearing vs the use of global negative feedback, it becomes much clearer. See

http://www.atma-sphere.com/papers/paradigm_paper2.html
for more information.

At it's most basic, the answer to you question is that audio deals with music, and music is art. Comparisons to things like computers, which are devices that are required to perform functions that have nothing to do with emotional content are, for the most part, irrelevant. There is a great deal of art that goes into the design of a truly great audio component. That is why many feel that as audio design "advanced", in many cases something was lost. As designers (and sound engineers) rely more and more on test measurements, and less on their ears, more and more of the human element gets lost: less art The trick is to use these "advances" in technology to serve the art, not to define it.

Not sure anyone answered the original question, which in other words is why can't the SS technology progress enough to rival that of tubes (that is, rival SS for those qualities most admire in tube design).

It seems there's a large number, if not majority, that prefer tubes despite their fussiness and maintenance. Then again, this is not the same demand that is there for faster computers, better cell phones, etc. Small market demand versus global need (and thus less money to be made by those with the capital to back the advancement of the technology). Most people that pay $ for music are ok with a cheap $500 receiver that plays music (or an IPod even...).

Sort of on the subject of this - Steve Nugent and Gordon Rankin were involved in a thread somewhere before (perhaps computeraudiophile.com) where I remember Gordon saying that tube design is inherently simple compared to solid state (less parts, less areas for address). In other words, tube equipment affords a simpler design and signal path, linearity, etc. Solid state has yet to match this. I'm too lazy to go find the thread, but it was interesting to hear the two debate the use of tubes versus solid state in equipment design.

Thanks you everyone for your informative posts.
Frogman/Elizabeth, I get your point about music as art. But I guess I will have to do some reading before I digest the fact that human progress could not achieve in audio, what they achieved in other fields. Interesting indeed!!

Because size matters!

Sony can't build a walkman with tubes inside, same goes for 99% of mass market audio gears out there. Imagine if Sony had to build a 5-channel HT receiver with tubes, it will take up quite a bit of floor space.

Same goes for media. Reel-to-reel, LP, cassette, CD, MP3, and who knows what's coming next. Each generation degrades the sound, but 99% of people out there don't care because they can carry more garbage with them everywhere they go.

Let me take a shot.
Music reproduction has to do with your ears and physical feeling in a room with it... Not complex number crunching storage devices, or flying an airplane.

So realistically your ears today or in 1950 would have been the same. Advanced audio today has to do with cheaper, better, faster, more reliable ways to keep it in your house more than anything, along with heat and efficiency, reliability. Not so much to how it sounds. The best guitar amps, pro studio equipment etc... still run on tubes, but there is also excellent or better solid state in some areas of audio depending how much your willing to spend.

This question and hobby unfortunately is totally disconnected from the standard "why has it not advanced" theory. Vinyl is crude and 90% of the time easily the recordings best the BEST sounding IPOD in the world! IPOD is advanced, its solid state, doest that mean it should beat a 10,000 dollar tube preamp and amp? Nope.

Video easily is explain as again video is seen, you can put one next to the other and compare with virtually no question from person to person. Audio is a whole different world and brain function, of course if you have bad eyesight and put on glasses all of a sudden you see things in high definition, of course if you are flying an airplane the best thing is reliability and accuracy not flying with vibration and failure sensitive tube devices.

Again has nothing to do with audio or the reproduction, heat, tubes, and analog period is how your ears work, digital and solid state are simply copies of reproducing it more efficiently but not necessarily better in all cases, faking it and making them as close as possible is all we are doing in home anyway, should a violin, grand piano or drum kit be solid state? Or should it still just create sound based on mechanical vibration? That of course has nothing to do with Tube vs. solid state, however reproducing it can.

Anyway bottom line is your ears work the same either way, what works for you? Natural sound can be had many ways, nobody has an answer to the best for every situation, but for sure the more artificial you make it sound, the less involving it can get, tubes and vinyl for example keep everything in the analog realm with no conversion, so it appeals to some more. But they have not necessarily discounted or realized you can in fact get similar or better results with "Higher" technology.

Solid state technology DOES have an answer to the imperfections of transistors cited by Atmasphere. Digital amps. (You could make a digital amp using tubes, but there would be no point to it). In a digital amp the output devices are full-on or full-off, so their linearity is a non-issue. The analog output is modulated by the duty cycle (ON/OFF timing) of the output devices, and there is no limit to the accuracy achievable, except cost.

Undertow said:

Advanced audio today has to do with cheaper, better, faster, more reliable ways to keep it in your house more than anything, along with heat and efficiency, reliability.

I think this is the answer in a nutshell. I don't think the early engineers said "let's develop SS because it sounds better." But, rather, the bean counters told the engineers to develop a way to produce electronics faster, cheaper and with greater reliability.

Eldartford, what you say is partially true- the problem is that the distortion signature still enhances odd-ordered harmonics.

Milpai, humans *were* able to make advances in audio- and it turns out that tubes are the way to do that- appropriate technology IOW.

Atmasphere - As far as I know class D amps enhance a little bit even harmonics (being slightly tube-like) and not the odd ones. It depends also on output configuration - from what I've heard full bridge amps (Icepower) sound more like very good tube amp while half bridge (Hypex) sound more like very good class AB. Tube amps have capacitors and transformers in the signal path - serious limitation in my opinion.

Eldartford - Early SS amps that won battle with tubes had THD in order of 0.00001% and tons of TIM thanks to insane use of global negative feedback. The problem was that TIM was discovered in 70s'. In really bad case output transistors are momentarily overdriven and stop responding for a moment after transition since charge at the junction is trapped and takes time to get out of the saturation. We don't hear tiny gaps in sound because our brains fills them but it makes us tired after a while. It cannot happen in class D. As for limitation - high power Mosfets are slower and carrier frequency is often too low, limiting bandwidth (smaller Icepowers have higher bandwidth than the large ones). 60kHz bandwidth might sound enough (200ASC) but phase shift jumps to 20 deg at 20kHz. Are harmonics added properly? Mosfets are getting faster and stronger every year and in near future class D will improve even further.
Today's class AB amps have gain before feedback often around 4000 while class A amps have gain of few hundred. I would rather have more THD and less bandwidth than TIM and blown-up upper odd harmonics - but good THD and bandwidth spects sell amplifier.

The way I understood the OP's question (or maybe the question I want the answer for) is why hasn't anyone built transistors that can sound as good as tubes to the ear? I don't think it's the matter of technology today, as we pretty much understand how transistors and tubes sound different. I don't think it's economics either. Imagine iPod with sound as good as good tube headphone amp. I bet whoever that can make transistors with tube sound will make a lot of money.

Actually there are transistor amps that do that, but you can count them on one hand with fingers left over. None of them employ global negative feedback- it seems that NF is a design element that has been holding advancements in audio back.

So far the Ridley Audio amplifier is the best example I have seen of what can be done with transistors. Last I heard, it made 100 watts and cost about $100,000 for a pair. There is a heater circuit for the output devices that makes the amp run every bit as hot as tubes. It is better than many tube amps I've heard.

I have yet to hear a class D amp come close, but that technology is still evolving and may yet bear fruit.

Jylee, you are correct. That was my original question. I also wonder sometimes that maybe SS is better than tubes currently - but maybe are we held back by our own "habits" of listening, such that anything other than tube seems "less" in our world!!
Semi went to the extent of size and Undertow mentioned the iPOD. When I mentioned advancement, I did not mean SIZE. Look at my evolving system - I am going from an integrated to a separate preamp and amp. I still cannot switch to iPOD or data-servers. Maybe they are as good as the current mediums I am using - but maybe I am biased to my current medium and that is preventing me from switching to digital files.
As for music as an art - I completely understand. In fact that is what I "try" convey to my non-audiophile friends. But remember if you can create art using more advance technologies, that can lead to betterment of art - why not explore it? Cave men used rocks, charcoal and other items to create art. Why did modern man come up with ink, paper and other stuff? Maybe SS audio has not been fully explored.
Atmasphere, I understand that humans did advance to Tubes. But looks like they are stuck there :-)

Milpai, true, we are stuck- for now. Believe it or not I would be the first to jump on the transistor bandwagon if I thought I could do it without sonic sacrifice!

If we listen to SS amps long enough humans will evolve to prefer odd harmonics :-)

"If we listen to SS amps long enough humans will evolve to prefer odd harmonics"

I must be evolving really fast since I don't like enhanced even harmonics already.

Kijanki, the difference between audible enhanced even and odd ordered is something like this: with the evens, we start to hear that they are there with about 0.5 to 1%. With the odds, we are well aware of them when they are about 0.0005% or so.

The evens can be canceled by fully differential balanced operation. Its not a great benefit to have the output of the amp be push-pull if you don't do it throughout because all the gain stages make distortion. So if you operate fully balanced throughout the circuit, the overall even-ordered harmonics will be very low or non-existant.

After that you do your best to not enhance the odd orders- zero feedback, class A operation, minimal gain stages, higher quality components, more linear amplification (triodes as opposed to pentodes for example) and so on.

This, BTW, is one of the very clear 'audio advancements' that has occurred in recent years. There are tube and solid state amplifiers that use these techniques today; thirty years ago they did not exist.

Atmasphere - People often treat enhancement of even harmonics as a virtue (warm sound). I don't want my gear to enhance anything (if possible).

Kijanki, you and I are on the same page!