Why do we want to distortions?

@atmasphere   Thank you for the clear and detailed response. You provided me a level of education in audio that I never thought would be obtained on a forum.   

@atmasphere 
thank you thank you thank you!
I have enshrined your message in Apple notes where I am sure I will refer to it frequently in the future

what I am trying to understand is if the original recording is with euphonic distortions that are deemed as positive then don't we want the most transparent system to hear the original  and  How does tube euphonic distortions add a stage to the sound?

I wouldn't worry about the original recording! Some are great and some are terrible. The way distortions occur and how some are added in the studio causes things to work out differently. When you are playing back you simply want the most transparent you can get but without the playback editorializing on the content.

By this I mean the playback apparatus has to be well-behaved. I've seen some systems sound great with a great recording and then freak out when a poor recording is played. But get that same poor recording on a properly set up system and while it won't sound great, at least the playback won't exacerbate problems.


That is one reason I eschew brightness and harshness in the playback as it will make bad recordings worse. It sucks when a favorite artist has a lousy recording; it sucks worse when your system can't be graceful about it.


With regards to sound stage, it appears that a prominent 2nd or 3rd harmonic somehow helps the ear winnow out detail in the recording. I do not know why this is the case so I'm going on a lot of anecdote (and familiarity with recordings I've made on location and in the studio), but I did encounter one paper where the experiment was to add a 2nd harmonic to the playback and improved soundstage was the result. I think more research is needed. At any rate in my own work it appears that the *amount* of distortion isn't the point- but what is important is that even if the distortion is super low, most of it should be the lower orders.

Thanks for the education atmasphere. One can never have enough knowledge.

A very interesting thread about distortion. It's really a subject that is hard to understand as there are so many aspects also related to our hearing and perception of sound.

To me it seems like if we in a playback amplifier add some low order harmonic distortion with a distribution similar to our aural harmonic distortion, this may be an interesting way forward. In a paper from Cheever, 1989 there is an interesting discussion about aural distortion and high order distortion. Both Cheever, Pass and several others agree on that to much negative feedback create high order harmonics that we are very sensitive to. Cheever also discuss aural masking and the effect by adding such distortion to the playback system. But does this masking effect also apply to to some extent to intermodulation distortion? I have not a clue.

Is it so that we should focus on how much an amplifier deviates from our hearing aural harmonics? I had the opportunity to borrow a Benchmark AHB2 for a weekend. To listen to it and to measure its performance using my audio measurement system. From a pure "standard" measurement point of view its really hard to beat its performance. Super low distortion for example. But to me it was not playing musical. Transparent and with high resolution of course. Not engaging but very neutral. This amplifier is a technical masterpiece. Using forward error correction that from a measurement point of view more or less eliminate distortion. At least to very, very low levels. By the way, error correction, is to my knowledge a superior method to manage different kind of distortions compared to for example global negative feedback. But that's another story.

To me, there is more going on than masking effects by adding a falling level of low order harmonics. Maybe its about the improved dynamics?

Here is my idea... Instruments may be more clearly defined in all of its natural harmonic spectra by adding well defined low order harmonics. We get the masking effect and we also "enhance" the natural sound of voice and instruments if we add some harmonics that are inline with our hearing harmonics. We are very sensitive to unnatural and high order harmonic distortion and this would just make use of the way our hearing and perception of sound works. As long as we stay close to the aural harmonics we just get a more musical presentation. Without changing the timbre (I think). I think this might have a good effect on the holographic image as well. Hope these ideas may bring something to the subject.