An Harmonic story or a story about Harmonics.

A customer of mine brought up a discussion on why tube amps sound better,
even though the measurements are clearly in favour of their solid state counterparts .
I showed him some spectrum analyser graphs of what I think are ideal harmonic distortion and he theoretisezed how they could benefit an audio signal , it was very interesting and therefore I wanted to print it . I'm also using a name homologue but its a real name for a fictive discussion.

Imagine :

Benny Kim, a world-renowned violinist, with his Stradivarius violin. A Stradivarius violin is irreplaceable, even if it is insured the value to the player makes the money worthless, that's the reputation that these gems have.

Suppose the violin gets stolen.
The police after finding the Stradivarius violin back wants to be sure that it really is the correct violin of Benny Kim, so they blindfold him and make him listen to a number of different violins at the police station, can he recognise his violin ?
Probably yes, for a trained ear it should be easy, but Benny is sitting in a police office and is under stress and not in his familiar surroundings (conservatorium or practising room ) and still he probably manages to recognise his violin .
This means he can discern the different harmonic content of each of these violins played to him.
And the difference would be almost immeasurable with state of the art equipment I believe.
We probably are all able to hear such fine nuances in the harmonic content, but we are not trained for that.
This alas also means that our ears can be easily fooled and that happens quite often!!!

Suppose you listen to a concert performed by Benny Kim, you are totally enthralled by the performance, you have a top seat and the acoustics are excellent, you are extremely happy and decide to buy a few CD's.
At home you are full of expectation to rediscover and relive the moment you cherished, you listen carefully to Benny 's violin play, but very soon you are disappointed and realise it is far from what you expected.

His violin doesn't sound as good as it did live.

Off course you have enough experience with high end to realise that probably no live recording can match a live performance, and you know that a mountain of electronics are necessary to bring back the sound of the violin from the bits and bites on the cd and this off course surely happens at a cost, some loss of quality, but never the less you expect better. So you return to you're favourite high end shop and you explain the problem and they propose you to take out an afternoon and listen to different sets with you're favourite recordings.
You get to listen to a certain single ended tube amp and it already sounds a lot better, after a trial at home you are sure, this is the way to go.
Now the cd's of Benny Kim have a new dimension, extra depth, more of everything en above all they are more musical.

The tube virus caught you and you do some research and to you're astonishment many different tubes exist that are either from different manufacturers and have different sonic characteristics or are pin compatible and all should improve you're tube amp dramatically.
Finally you end up with a tube guru and with the new tubes you are one step closer to audio Nirvana you're happiness and satisfaction are great.
One of you're friends happens to be a great cynic and electronist and has an electronic lab to his disposition, he proposes to measure you're amp to see what kind of distortion it is producing , since you are curious why not, on the scope, with sine wave at the input, the output signal looks identical , but on the spectrum analyser, there are tons of added harmonic content next to the original pure signal it was supposed to amplify.

What is really happening ?

Lets start again with Benny Kim, his cd's are recorded in some studio or concert Hal, live or not live, long cables, tons of equipment, noise gates, limiters, expanders, reverbs, mixing tables, recording equipment, usually today the signal are all digital, and go through many Digital signal processors before ending on a hard disk and being edited on a computer.
Then the signal is reedited in the studio, sometimes they add reverb, ect .
(now a days its even popular in studio's to add a tube stage just to get a WARMER sound )
All in all it is a very long process for the signal before it is put on the final cd and shelved in the stores.
So it is not so surprising that something is lost slowly, and due to the high tech we don't lose much but what we lose are subtle harmonics.

Since the complete signal is also constituted of very fine harmonics, that are barely measurable it is understandable that they are drowned in noise at the end of the studio process.

So the sound of Benny beautiful Stradivarius is already lost at this stage.

Of course we expect to hear Benny's beautiful Stradivarius again when playing on a high end set, alas we don't all have such a trained ear, this means that our listening abilities are handicapped and will be deceived easily into believing that we are indeed listening to Benny beautiful Stradivarius .
Now off course you are listening to the beautiful notes he played, and you are hearing them exactly as he played them, only different.

This is the heart of the discussion :

The single ended tube amp adds the missing harmonics to some degree, the ones that got lost in the recording process and in the reproduction process, the musicality is back, but it isn't the same violin!!!!!

This discussions explains why so many systems exists, it's to me the first explanation that makes sense, let me explain:

Speakers have very high distortion figures compared to amplifiers, I would say the market is swamped with different speakers and different amps.
And all claim to be the best, or best value.
And what complicates things further is that distortion changes heavily depending on the volume setting, and therefore different combinations of amps & speakers give different results as the volume setting changes!
The other aspect of course is how much did the recording lose?

The question is would Benny recognise it is his Stradivarius if he were to listen to a set of different violins on a high end set?

Alas I didn't get Benny's opinion on this .

Benny Glass 2004 webdesign