How close to the real thing?

Timlub ,

Franky has an Holodeck, you will never match his soundstage

:):):)::)

Weseixas, " ... has a Holodeck" -- nicely put :-)

Timlub, unfortunately the key phrase in your comment is "distortion is so far below our hearing that it was unconceivable to hear" -- of course distortion is easy to hear! My system distorts, your system distorts, everyone's system distorts. That is why every system sounds different from every other system, every time you change something in a system it sounds different, because you have changed the distortion component. If you have two widely differing systems that don't distort then they must sound identical.

I think the problem area is in the use of this word "distortion". One dictionary says "a change in the wave form of the original signal", which sounds fair enough to me. The argument would then be how MUCH change is allowed before you would call it distortion; I would say only so much that you can hear a difference between the original signal and the distorted one: if you can hear a difference between the original and the altered signal then you can hear the distortion! Two systems sound different, which is the distorting one? Both, of course, as compared to the original waveform.

Another way of looking at it, is that there are 2 tiers of distortion, let's call it "macro" distortion and "micro" distortion -- sounds familiar ... :-). Everyone knows macro distortion: boomboxes overloading, speaker cone rattling, treble ripping layers of skin off your eardrum, you could even include really bad digital playback here; all very easy to pick.

Micro distortion unfortunately is everywhere, it's all that low level stuff that makes one system sound different from the next. But everyone normally calls it the million and one other things, see J. Gordon Holt's Audio Glossary. Interestingly he includes "distortion" in its own right, firstly as a "true" definition: "1) Any unintentional or undesirable change in an audio signal." and then to highlight most people's concept of "macro" distortion: "2) An overlay of spurious roughness, fuzziness, harshness, or stridency in reproduced sound." But in the majority of the other, sound related terms in his glossary he specifies virtually every other type of "micro" distortion: dry, forward, haze, liquid, etc, etc. Talking of THD and IMD, these are just straightforward ways of putting numbers to the distortion in a very specific setup, somewhere between maximum "macro" and minimal "micro" ...

So, what to do? My "solution" is to eliminate, obviously, "macro" distortion, and then as much of the unpleasant, AUDIBLE "micro" distortion as I possibly can, which is, very, very difficult. How do I know I've got there? When I can change something on the system and from the point of the auditory experience nothing changes! And, at this point the sound becomes "real" ...

Frank

"If you have two widely differing systems that don't distort then they must sound identical".
So, when 2 different cone materials sound different on speakers, one is more distorted or when you roll tubes for a completely different sound, one is distorted, or when a designer changes from bipolar to mosfet or vise versa, they sound different because one has distortion or when we add spikes to a speaker and the sound cleans up a bit, we have lowered distortion or 2 identically spec'd phono cartridges sound completely different, its because of distortion????? Does Silver copper or gold in wire carry more distortion??? They all sound different. I can go on and on.... Your comments do not hold merit. I'm glad that you have a Holodeck, distortion matters overall, no argument, but it is not the one thing catch all.
Sorry Frank, I can't agree on this one.... I've been convinced of a few things on here...Thanks Atmosphere & Almarg, but you've got a long way to go to change my mind on this one. Good Listening, Tim

Its true that by definition a reproduced signal that is not exactly identical to the original source (ie exactly the same as the real thing) is distorted and that the reason no two systems deliver the exact same sound is because each distorts the input signal differently.

So not all distortion is necessarily unpleasant. In fact some may be enticingly pleasant! Others will induce different responses, both positive and negative.

FWIW, low ordered distortion is pleasant, but it does obscure detail, and the ear tends to hear it as a fatness or warmth in the sound. Lower orders are the 2nd, 3rd and 4th.

Transistor amps have almost none of these distortions, but they are common with SET amplifiers. P-P tube amps on the other hand tend towards the 3rd and 5th.

Now it is the higher odd orders that our ears use as loudness cues. Anytime they are distorted, the amp will sound louder than it really is. This is why SETs will sound very 'dynamic' for their power, as normally they don't make much distortion, but if you push them (which is what transients do) then the loudness cues appear **but only on the transients**.

Transistor amps tend to have these higher odd orders all the time. This is one of the reasons they tend to sound hard or bright. Now its important to note that these harmonics do not have to be very distorted, usually 100th of a percent are audible, simply because these harmonics are so important to the human ear.

This, BTW, is why two amps can seem to have such different tonal characteristics even though they both measure flat frequency response on the bench. The addition of global negative feedback to any amplifier will increase the odd-ordered distortion slightly, which is why any amp with GNF will tend to sound brighter even though frequency response is unaltered.

(The trick, IMO, is to build an amplifier that does not use feedback, and use other means to eliminate distortion.)

The bottom line here is that distortion is always audible and to nearly anyone. Its just that it does not *sound* like distortion to us, often it sounds like a tonal aberration ('bright' in the case of many transistor amps, 'caramel' in the case of many tube amps).