I can hear 1% thd on a 1k sine wave. It sounds like a "bright" 1k, sort of a triangular waveform. 1% thd with music is a different story. Most speakers have well more than that all throughout the midband range. Mechanically induced HD sounds different than electronic HD.
How much distortion has full range Lowther driver in Oris like horn ? The graph looks like Himalayas BUT ...
Idea of thd is not ment for listener . Its for amplifier . Ofcorse listener can listen to thd more than 10% like hard core rock or something . Desortion itself isn't the problem . Desortion due to amplifier is . Therefore its not the matter of you can hear it or not . Its the matter of is it present or not .
I cannot heat 10% even harmonics. I think I even like some even harmonics... I know... I am bad.
My often favorite amp is my little flea power 'kitchen amp' using a 6AS7, driven by a current mirrored 6922. The output from the 6922 is in phase with the signal, as opposed to a normally plate loaded 6922, so instead of some harmonic cancellations, it is actually harmonic addition going on. The output power is just above 2W. At 1W and more the 2nd harmonic is at about 10%.
This amp sounds fabulous. I've had my daughter sitting in the living room listening to music and ask me why her music sounds so much better in my house than at her moms... and she is not interested in audio gear at all, just likes to listen to music. I've taken this amp to meets because of it's high even harmonics, and all who listen to it really love it.
I think we can easily hear odd harmonics at lower levels than this, but even harmonics... not me at least. Or if I hear it, (which I dont consciously) I actually like it.
My often favorite amp is my little flea power 'kitchen amp' using a 6AS7, driven by a current mirrored 6922. The output from the 6922 is in phase with the signal, as opposed to a normally plate loaded 6922, so instead of some harmonic cancellations, it is actually harmonic addition going on. The output power is just above 2W. At 1W and more the 2nd harmonic is at about 10%.
This amp sounds fabulous. I've had my daughter sitting in the living room listening to music and ask me why her music sounds so much better in my house than at her moms... and she is not interested in audio gear at all, just likes to listen to music. I've taken this amp to meets because of it's high even harmonics, and all who listen to it really love it.
I think we can easily hear odd harmonics at lower levels than this, but even harmonics... not me at least. Or if I hear it, (which I dont consciously) I actually like it.
The 2nd harmonic is about as benign as it gets. Musically speaking it's exactly an octave higher, so it's perfectly consonant.
H3 is an octave + a perfect 5th so it's also very consonant, just a little less.
H4 -- 2 octaves
H5 -- 2 octaves + major 3rd
H6 -- 2 octaves + perfect 5th
H7 -- 2 octaves + (blues) 7th
H8 -- 3 octaves
H9 -- 3 octaves + 2nd
Etc...
They tend to get more dissonant further up (bearing in mind that the tuning is perfect, not "equal temperament"). Which is a problem for THD as it gives equal weight to all harmonics, which is nonsensical.
Distortion reduction techniques like NFB tend to 'flatten' the gain of the harmonic series, reducing H2, H3, H4 the most, while (often) increasing the higher ones. Brute force (extremely high gain and high NFB) could bring down all harmonics, but probably at the cost of a high part count, and introduces new ways for various things to go wrong. Not to mention inelegant design.
(Typical) hearing sensitivity is easily 40dB higher at ~4kHz compared to 100Hz.
Relative phase may make a difference, too. There is more than one way to calculate THD: either taking phase into account or only the absolute value of harmonics. This probably makes a difference to audibility and subjective experience. For instance, a series of harmonics of equal amplitude and aligned in phase produce a very sharp sawtooth-like wave with tall spikes, and not much area under the curve. Without actually testing it, this already suggests a potential to shred the eardrums despite not producing much discernible tone, and minimal RMS power.
Re: people claiming to hear 0.0xx%. I wouldn't discount that because of the above. But it could also be IMD.
AFAICT, negative feedback actually introduces an additional mechanism for IMD to take place. IMD is what causes H1 + H2 to create the harmonic series of H3, H4, H5... in the first place. For a pure sine wave, the results are harmonically related, but I wouldn't be too confident if the inputs are real music signals.
H3 is an octave + a perfect 5th so it's also very consonant, just a little less.
H4 -- 2 octaves
H5 -- 2 octaves + major 3rd
H6 -- 2 octaves + perfect 5th
H7 -- 2 octaves + (blues) 7th
H8 -- 3 octaves
H9 -- 3 octaves + 2nd
Etc...
They tend to get more dissonant further up (bearing in mind that the tuning is perfect, not "equal temperament"). Which is a problem for THD as it gives equal weight to all harmonics, which is nonsensical.
Distortion reduction techniques like NFB tend to 'flatten' the gain of the harmonic series, reducing H2, H3, H4 the most, while (often) increasing the higher ones. Brute force (extremely high gain and high NFB) could bring down all harmonics, but probably at the cost of a high part count, and introduces new ways for various things to go wrong. Not to mention inelegant design.
(Typical) hearing sensitivity is easily 40dB higher at ~4kHz compared to 100Hz.
Relative phase may make a difference, too. There is more than one way to calculate THD: either taking phase into account or only the absolute value of harmonics. This probably makes a difference to audibility and subjective experience. For instance, a series of harmonics of equal amplitude and aligned in phase produce a very sharp sawtooth-like wave with tall spikes, and not much area under the curve. Without actually testing it, this already suggests a potential to shred the eardrums despite not producing much discernible tone, and minimal RMS power.
Re: people claiming to hear 0.0xx%. I wouldn't discount that because of the above. But it could also be IMD.
AFAICT, negative feedback actually introduces an additional mechanism for IMD to take place. IMD is what causes H1 + H2 to create the harmonic series of H3, H4, H5... in the first place. For a pure sine wave, the results are harmonically related, but I wouldn't be too confident if the inputs are real music signals.
Test your own limits of distortion audibility with the Klippel test. Use good headphones and a quiet room late at night when ambient sounds are lowest.
https://www.klippel.de/listeningtest/
I scored quite high, meaning I can hear pretty low levels of distortion well below 0.5%.
https://www.klippel.de/listeningtest/
I scored quite high, meaning I can hear pretty low levels of distortion well below 0.5%.
You need to consider that 3H isn't so consonant when it occurs in a chord. In a C major chord you will get another G, a B and a D. And the effect gets worse with higher order harmonics: not just the odd ones but the 6th, 10th, etc. Also worse with minor chords as you get a Bb. The only harmonics that are truly consonant are the powers of two. The 'engineering simplification' of even and odd has been used for far too long.
THD is measured for a single tone so chords do not apply. The effect of reproducing the tones in a chord with a nonlinear amp is best measured as IMD and for an amp with THD = 10% the effect on your ears (and probably mood) won't be nice. High THD is only acceptable when musicians are playing in TDM. The best example I ever heard was from a high school friend's 4W EL41 SE: for (very) small ensembles it sounded much better and louder than my 15W 2X EL84 PP (on the same speaker). But that reversed completely when playing orchestral classical music ;-)
I'm talking about harmonics, not THD or IMD. Non-power-of-two harmonics are unpleasant in chords however they may be produced, including by an instrument itself.
If you did not hear a reference, then you will not be able to say distorted or not.
Same material played in the reference and the test system.
Same material played in the reference and the test system.
All even harmonics are exactly related to the original tone. As stated, they are higher octaves of the same note. The third harmonic is not exactly a musical 5th. It's often close enough to be considered consonant by most listeners. The third harmonic of A above middle C ( A4 = 440 Hz) is 1320 Hz. The musical 5th of A6 is E6 (1318.5 Hz) an error of 1.5 Hz. This error will not be detected by most listeners unless the H3 is very strong. The fifth harmonic is far enough away from a musical third for it to sound dissonant to some listeners depending on its level. The error on an A3 (220 Hz) note is 8.7 Hz. 1100 Hz (5th harmonc of A3) vs 1108.7Hz for D flat 6. Any IMD distortion present in the amplifier will made sum and difference products with these tones and the original note. It is very rare to find a device with significant harmonic distortion that does not have IMD. Even at low levels the IMD products will contribute to listener fatigue and create that "veil" that audiophiles talk about.
At low frequency and higher volume our own ears is producing more than 10% 2nd harmonics according to research!
Our ears produces almost no 7th order distortion as a comparison.
THD does NOT take into account what type of order there is to the harmonic.
That's why i really do not like Amirs statements at Audio Science review, since he seldom mention this facts. He only focus on THD as a number.
THAT IS NOT SCIENTIFIC !
As an engineer you have to consider that there exists several other disciplines, such as psycho acoustics and perception psychology, and biomechanics.
It is the transfer of movement of the ear drum trough the different bones and to the small hairs in the inner ear that converts the sound to electrical impulses, that generates distortion in itself.
During development of compression techniques (such as mp3) a huge amount of effort was made to understand our ears... it is clear that lower order of distortion is masking higher order of distortion and that odd orders sounds worse in itself.
So that is the explanation to what we (audiophiles) have heard and understood for decades. Some type of distortion at 1% is more or less inaudible while some type (typically odd order of higher order) is terrible even at 0.01%.
Tons of research is done of course- on this topic, and unfortunately THD still is used as a number describing "sound quality" .
https://hifisonix.com/wordpress/wp-content/uploads/2017/11/Perceptual-Levels-of-distortion.pdf
Our ears produces almost no 7th order distortion as a comparison.
THD does NOT take into account what type of order there is to the harmonic.
That's why i really do not like Amirs statements at Audio Science review, since he seldom mention this facts. He only focus on THD as a number.
THAT IS NOT SCIENTIFIC !
As an engineer you have to consider that there exists several other disciplines, such as psycho acoustics and perception psychology, and biomechanics.
It is the transfer of movement of the ear drum trough the different bones and to the small hairs in the inner ear that converts the sound to electrical impulses, that generates distortion in itself.
During development of compression techniques (such as mp3) a huge amount of effort was made to understand our ears... it is clear that lower order of distortion is masking higher order of distortion and that odd orders sounds worse in itself.
So that is the explanation to what we (audiophiles) have heard and understood for decades. Some type of distortion at 1% is more or less inaudible while some type (typically odd order of higher order) is terrible even at 0.01%.
Tons of research is done of course- on this topic, and unfortunately THD still is used as a number describing "sound quality" .
https://hifisonix.com/wordpress/wp-content/uploads/2017/11/Perceptual-Levels-of-distortion.pdf
There are a few other things he does that are far from scientific*.
While they do have some useful data; the real purpose of the site is to reinforce and spread their beliefs on what is important in audio, not to be impartial or scientific in their work.
The standard procedure there is if the outcome fits their fixed hypothesis then any questioning of the methods will be dismissed.
It is sad because it could be a very useful site if the methods were continually looked at and improved. As it is, it is a place to gather and bash things that they all agree are bad and shouldn't exist because they don't want them.
*
-They mock anyone that does sighted listening comparisons, except Amir who always tests the equipment first so he knows what to listen for. If he hears that it is sounding bad then it is okay but if you hear that it sounding good then you are wrong.
-Vintage equipment of unknown background and repair status is often tested to show how bad it is with no way of knowing if it is performing anywhere near how it did when it was new.
-They continue to test tube amps even though harmonics will always give them a low number since he groups that with regular distortion.
-Speakers and lower power amps are generally driven far beyond the range any buyer of them would put them through. To most there, every piece of equipment must be able to produce live performance sound levels. No sane person makes a 5w amp and tries to drive inefficient speakers to hearing damaging levels.
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Nobody listen pure sinewave . Its too bland . No instrument is perfect . Hormonic make it lively . Many artist put hormonic knowingly in there mix . Also in today's world if you record a put out a music vedio with square wave sound . Then the Mob will go crazy haters will **** there pants . And critic's will say " ah so deep " . That is the world we livin .
Relative harmonic content of an instrument depends on the mode of playing. Because attenuation of soundwaves in air is frequency-dependent, the relative amount of harmonics for the same sound also conveys information about distance. Higher relative amount of harmonics (from for instance a predator) implies it's closer and might pose a danger. That mechanism could explain why high harmonics sound more objectionable than low ones. But before the level of "objectionable" is reached, the high harmonics already are / have been subconsciously processed and could influence one's judgment about quality of sound.