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In Reply to: RE: Here is the problem with this analogy. posted by fstein on November 13, 2015 at 13:59:31
nt
try it! you know you want to!
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And that's even measurable, although it can be at really low levels such that there are measurement difficulties: it is hard to see in all the noise and yet can still cause a problem.
But if you wanted to point at a problem area, that is a classic that's been around for many decades and not really been solved by solid state designers, although tube amp designers seem to fare better. You might see it as the holy grail; build a solid state amp that lacks odd ordered harmonic generation in general and you are on to something.
Honestly, that would represent transformation and it would likely end the market for tubes.
nt
try it! you know you want to!
-I have often found the use of that term to be misleading, wherein the designer felt it was 'negligible'.
The fact is no solid state amp is lacking that harmonic in such a way that it is inaudible (many tube amps have it too, but apparently in lessor amounts). It is true though that some have less than others- and are often described as having 'tube like' sound. But it is still present and audible as our ears are more sensitive to higher ordered harmonics like this one than the best test equipment.
Therein lies part of the subjectivst/objectivist debate which has been going on for decades and will continue until this fact is realized. I'm not holding my breath.
to recognize sound....Get a hearing test and your doctor can confirm this for you...Then compare that level to that of distortion spectra as measured for any number of ss or class d amps. You will find the amps are not outputing 7th harmonic at levels you can hear.
try it! you know you want to!
And FWIW I was not suggesting 'infinite sensitivity'!!
What I did say is that our ears can detect the 7th harmonic better than test instruments can. This is why two amps can measure the same bandwidth on the bench but one can sound bright while the other does not. Its not due to frequency response variation, its due to the fact that the ear/brain system converts distortion into tonality. This and the ear/brain system uses higher ordered harmonics in order to calculate how loud a sound is. In that regard we seem to have about 140db or so range. That's wider than a lot of test equipment can do...
I certainly have never read anything that gave a figure of human auditory thresholds anywhere near that, especially when the signal contains mixed frequencies...Best to keep in mind as well the limits of the source media as well: vinyl is good for about 50-70 dB; a standard cd/16-bit is good for a 96 dB range, and a 24-bit DVD has a theoretical 144 dB range.
I suppose it comes down to the fact that while our senses are rather limited, our ability to fool ourselves is almost endless...
try it! you know you want to!
Edits: 11/13/15
Our ability to hear a 7th harmonic does not require that the amplifier be playing quietly. It seems that you don't understand how distortion is perceived by the human ear.
We can hear that 7th harmonic quite easily regardless of how loud the amp is playing.
and that some amps don't produce audible amounts of harmonic distortion....
try it! you know you want to!
The ear is so finely tuned that it can pick them out easily. It does not matter that they might be at a low level- the ones of concern occur in the frequency bands to which the ear is the most sensitive, and in addition it uses those harmonics to calculate volume. Its more sensitive to them than it is the fundamental tones that made them!
You don't seem to understand how the ear works in this regard. Its not like an amp is on the bench where the less volume the less distortion.
try this:
https://phineasgage.wordpress.com/2007/10/13/audiophiles-and-the-limitations-of-human-hearing/
try it! you know you want to!
So now do you get that what you are talking about and what I've been talking about are not the same thing at all?
Once you do understand this, it will be like a light going on- you will instantly understand why the SS/tubes debate has been going on for so many decades.
if you can't hear it, it doesn't matter, 2nd, 3rd, 7th, ascending, descending, it is all MOOT if below the threshold of audibility. Of course, there are no tube amps I am aware of capable of that type of performance so it is entirely possible that your argument about the negative consequences of 7th harmonic is entire real for tube amps and why there are those who actually like the audible 2nd harmonic distortion that some tube amps produce.
try it! you know you want to!
Edits: 11/16/15
I really have no idea why you made this comment:
if you can't hear it, it doesn't matter, 2nd, 3rd, 7th, ascending, descending, it is all MOOT if below the threshold of audibility. Of course, there are no tube amps I am aware of capable of that type of performance so it is entirely possible that your argument about the negative consequences of 7th harmonic is entire real for tube amps and why there are those who actually like the audible 2nd harmonic distortion that some tube amps produce.
Could you explain the text in bold, as it seems to be at the heart of your comment.
I certainly agree that if you can't hear it then it does not matter. What you want to keep in mind here is that the ear converts all distortion into some type of tonality. The 2nd being 'warmth' for example, the 7th being 'metallic' and 'harsh'. The difference between the two examples is that the 2nd is relatively innocuous in "large" amounts while the 7th is annoying even though it might be buried in the noise of the test equipment and/or the amp itself.
It's all over ........ :)
Go Rossi ......
I mean with the amplifiers ....... :)
Go Rossi ......
(nt)
nt
try it! you know you want to!
nt
try it! you know you want to!
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nt
try it! you know you want to!
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Memo bis punitor delicatum! It's all there, black and white,
clear as crystal! Blah, blah, and so on and so forth ...
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So What , you NCore CLass-D guys get together and compare graphs ...
:) ROFL
.
Go Rossi ......
nt
try it! you know you want to!
...and the mouse in your pocket.
nt
try it! you know you want to!
and some amps don't produce harmonic distortion that is audible. Thus, 7th, 2nd, whatever, if you can't hear it, it doesn't matter! Your comments on the conversion of harmonics to tonality only applies to those that are audible! Since there are no tube amps I am aware of capable of amplifying the input signal without producing any audible harmonic distortion, your comments are certainly relevant in regards to tube amps. There are, however, ss and class d amps that are indeed capable of amplifying the input signal without producing audible harmonic distortion and thus your comments about tonality are pointless in regards to amps which do not produce audible harmonic distortion.
try it! you know you want to!
Its like herding cats.
I don't know of a transistor amp wherein the higher ordered harmonics are inaudible even when they measure in trace amounts. Such a thing does not exist. The harmonic structure of all amplifiers is audible.
Since your education about the human ear is obviously limited, this conversation will simply go in circles. Instead of trying to make me wrong, you might instead take some time to study how the ear/brain system works. Obviously you are a proponent of class D; like all other amps class D has particular artifacts related to distortion that can be heard by the ear. If you at least knew that the ear can do such a thing it would open the up the possibility to do something about it. You can't do that if you are operating with a blind spot!
"...you don't want ANY 7th order harmonic distortion."(emphasis mine)
He doesn't mention anything about thresholds of audibility.
That's your strawman.
that anything below the threshold of audibility is moot. There is no straw man, sleepy...
try it! you know you want to!
...you have no understanding of what Ralph is telling you and Curl is saying.
Hint: they aren't talking about steady state sine wave measurements.
nt
try it! you know you want to!
-
then let me know how you or anyone else can hear its harmonic distortion when it's -100dB down and below the threshold of audibility. As you have said, "doesn't matter if it isn't audible...."
If you think it is audible with a complex signal, show some data to support you position.
try it! you know you want to!
Edits: 11/16/15
Think about the distortion riding on top of the energy of the waveform (a little calculus is helpful) and you will see what the problem is.
I couldn't disagree more strongly with one sentiment expressed in the linked article:
"In other words, it's not really worth trusting an audio reviewer who is older than you are, because there is a range of higher frequencies that you can hear while they cannot. "
While I could detect active burglar alarms at age 18, I couldn't begin to hear the kinds of differences among audio gear that older, trained ears I knew at the time could. There's more to music than the last octave.
In fact, I find getting the midrange right far more important than either extreme.
Music does not consist of isolated sine waves. Therefore, a test of how an amplifier responds to isolated sine waves can not completely characterize the response of the amplifier to music.
"Harmonic distortion" is not a fundamental characteristic of a system. It is one method of measuring the non-linearity of a system.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
nt
try it! you know you want to!
It has been a long time since I read of these things (I think they were in latin) and I'm sure/I hope there's been more research since but my understanding is that, yes, something like a 140dB dynamic range might be possible from a tone played very loudly to one played very softly (even below background noise) but certainly not simultaneously!
IIRC, the ear has a working dynamic range much, much less than that, which depends on the loudest sound and tone spacing. In those terms hearing a harmonic 140dB below the fundamental is just not plausible.
This masking effect is interesting because I wonder if the relatively high levels of 2HD & 3HD in valve amps swamps-out the subjectively deleterious effects of higher harmonics, rather than the claim that these amps are free of high order products.
13DoW
And that is in the range of max sensitivity of the human ear (audibility thresholds depend on frequency!). When you add in masking effects of multi tone sounds, it is MUCH MUCH less, no matter what the frequency.Keep in mind the playback media range as well- if you are listening to vinyl, the range is only 70dB or so, redbook, better, and dsd closing in 140 dB. So with vinyl, if your amp's harmonic distortion is -100dB, my understanding is the media is in capable of resolving it regardless! Lots of tube lovers also love vinyl. Maybe because its limited dynamic range masks some of the distortion of their amps which would otherwise be audible with cd....
All this talk about higher order harmonics, harmonic patterns, etc., is meaningless if your equipment is capable of reproducing the signal with distortion levels BELOW the threshold of audibility. Few amps are capable of doing this, certainly not tube amps, but there are some that can. Of course we'll then hear about how terrible they must be because they use feedback. And feedback is bad because it creates higher order distortion products. A circular argument that fails to understand that unlike SET amps and other tube amps, not all amps produce audible harmonic distortion.
Of course there is nothing wrong with enjoying that tube distortion. Many do...
try it! you know you want to!
Edits: 11/14/15
You seem to talk out of both sides of your mouth. In one place claiming that any distortion products below -80 dB are inaudible and in other places touting the use of very high amounts of NFB to drive distortion well below that. Seems to me that you're just cherry picking your arguments.
Based on relatively new work it seems the pattern of the distortion is quite important. However, it is quite well known that even several percent 2nd order is inaudible while even very low amount of high order is audible.
For many musical instruments, the second harmonic is actually louder than the fundamental, so it should come as no surprise that adding a couple percent of 2nd harmonic isn't audible as "distortion".
"Secondly", (ha!, I made a funny), odd order harmonics give instruments more "bite" or "edge". As a trumpet player, this is quite evident to me in the sound of various trumpet brands and models. This is why we describe various trumpets as having a comparatively more "symphonic" sound or a more "jazz" sound. Take two trumpet models from the same manufacturer - Yamaha. The Yamaha "Chicago" horn has a fuller and more sonorous sound than the Yamaha "EM" (Eric Miyashiro) horn, which has more "sizzle". The same concept holds true for audio system components.
Thirdly, with regard to masking and psychoacoustics, it has been studied and shown since at least the 1950s that these general conditions apply:
1. Lower tones are better at masking higher tones rather than vice versa.
2. Tones which are harmonically related and fairly close together are more easily masked than tones which are not.
3. The "success" of the masking is related to the relative levels of the tones.
Folks who wish to explore the topic in more depth should go to the Audio Engineering Society website (aes.org) and the Acoustical Society of America (acousticalsociety.org). Even if you're not a member, you can search and peruse abstracts and purchase the papers for a fee. The topic area is also covered in Eric Heller's excellent "Why You Hear What You Hear" and other academic texts.
:)
It all comes crashing down at clipping .... Big un over little un .....
Go Rossi ......
Well, when an amp clips then it is of course not making the same distortion pattern it was before it was clipping...that is why one should avoid clipping. That being said it has been demonstrated that an amp without negative feedback will recover from clipping much fast than one with a lot of feedback. Clipping recovery can go a long way towards masking clipping because it is usually at high volume levels where our hearing is less sensitive...if it is short enough.
I agree. The pattern of clipping is important.
I was given some clipped recordings to restore and I started doing some experiments by taking clean digital recordings (24/96) and deliberately clipping them and then doing listening tests. In most cases clipping one cycle of the waveform will be inaudible, while the same clipping applied to multiple cycles will be audible. If one note is clipped it may be hard to notice the harshness and it may appear as just a bit more dynamics by the musicians. However, if the damage repeats for several notes then it can be perceived as a defect, either with the recording or the musicianship. In some cases repeated distortion won't be perceived as a deficiency in the sound quality or musicianship, but the listener will get a headache from listening. (I didn't try to do any scientific tests to "prove" these conclusions, because they appeared to be completely obvious.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
It doesn't get worse than digital clipping....
Go Rossi ......
Some of the tapes I worked on had analog clipping and they sounded different than digital clipping. In one case, the analog clipping wasn't really on the tape, it was a very, very hot metal cassette tape and with the gain knob on my cassette player cranked up the analog output stage of the Nak cassette deck was clipping. After I discovered this situation though careful listening I changed my procedures and ran the gain up on my ADC and ran the gain down on my tape deck. (There wasn't any S/N problem due to loss of bit depth when recording 24 bit audio from cassette tape.)
The problem with digital clipping is that it voids the preconditions for the Nyquist theorem to be applicable. As a gross example of that, consider a 1000 Hz sine wave. With purely analog clipping one will get a series of odd harmonics, 3000, 5000, 7000, etc... But if you take a digital square wave (+1 and -1 samples at 1000 Hz) one will get all kinds of alias products that will be at odd frequencies, including beat tones below the 1000 Hz fundamental. These will show up on a spectrum plot (FFT) and will also be clearly audible, especially if you use a sweep tone. A sweep tone with analog distortion will move in one direction. A sweep tone with digital distortion due to aliasing will have "birdies" moving in the opposite distortion.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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