The confusion is that "overtone" here is not being used as a synonym for "harmonic"...
Careful use of language is needed.
Harmonic:
1 - A tone that is a component of a complex sound
2 - Any of a series of musical tones whose frequencies are integral multiples of the frequency of a fundamental
Overtone:
1 - A musical tone which is a part of the harmonic series above a fundamental note, and may be heard with it
2 - A component of any oscillation whose frequency is an integral multiple of the fundamental frequency.
It is all the one and same non-linearity, regardless the measuring method use. The methods may just be less or more revealing the non-linearity types. Harmonic distortion of 2nd order creates all kinds of intermodulations as well, which are definitely not ear pleasing.
The overtone and harmonic series are practically identical but confusion arises because the harmonic series has no fundamental while the overtone series does.
If we stick to A220 the overtone series is the Fundamental (220Hz), 1st overtone (440Hz), 2nd overtone (880), 3rd (1320Hz).
The harmonic series looks like this: 1st harmonic (220Hz), 2nd harmonic (440Hz), 3rd (880Hz) and 4th (1320Hz).
Fundamental = 1st harmonic, 1st overtone = 2nd harmonic, 2nd overtone = 3rd harmonic and so on.
If we stick to A220 the overtone series is the Fundamental (220Hz), 1st overtone (440Hz), 2nd overtone (880), 3rd (1320Hz).
The harmonic series looks like this: 1st harmonic (220Hz), 2nd harmonic (440Hz), 3rd (880Hz) and 4th (1320Hz).
Fundamental = 1st harmonic, 1st overtone = 2nd harmonic, 2nd overtone = 3rd harmonic and so on.
The series yes, but an overtone doesn't have to be an integer of the fundamental whereas a harmonic does. Overtone - Wikipedia
equal tempered scale is far from mathematical:
here is its distorsion:
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An externally hosted image should be here but it was not working when we last tested it.
That is just one method to distribute the Pythagorean comma - in this tuning no intervall other than the octave is in tune (eg. a pure 5th is about 702 cent - not 700 = 7 HT * 100 cent).
Further reading eg. The Graphical Guide To Tunings, by Gunnar Tungland.
Just so.
The first overtone (where some folks expect a Second Harmonic) of 220Hz on piano is not 440Hz but nearer 441Hz.
(Actually it is likely the nominal 220 strings are tuned near 219Hz, so their overtone lands near 440.)
On a perfectly limp or hinge-end string it would be 440Hz. But piano strings are so stiff that the end-effects raise the overtone frequencies.
If tuned "exact", the overtones of lower notes would *beat* against the fundamental of upper notes and sound sour. "Stretch tuning" sets the fundamental of the upper note to the (sharp) overtone of the lower note; typically a running average over a couple octaves.
Point is the Overtones of piano (and most instruments) are not Harmonics but enough "off" to notice. This makes instrument overtone timbre different from tube/FET harmonic distortion.
Hi All
I realize that my headline for this thread was not good at all, as it has now turned into a long row of postings on purity of sound reproduction, what harmonics actually are, and how to tune a piano or a guitar!
My intention was a discussion on how to actually go about creating someting like the SSL Fusion, Vintage Drive, the circuit needed, different solutions, schematics, actual experience with such circuits etc. Only two responses to that; the H2 circuit by Nelson Pass, and the link to the Aphex Aural Exciter.
I have now Sim'ed the H2 circuit. A very simple and clever little circuit. It more or less does what it says, produceses primarily H2 distortion, but also a little 3'rd and 4'th. The circuit (as also described by Mr. Pass) is a little fiddly to dial in to the wanted distortion spectra. Also I realize that a placement in the chain just before the power amp, is not really the best, as it will very much depend on the "size" of the amp, how much distortion you'll actually get.
The H2 circuit will give lower distortion al low levels and higher towards higher levels of input. Meaning that if you have an input sensivity of say 0.775 V for full output, then you are likely to get to the max distortion level much more often on a 50W amp, than on a 300W amp. You could of course ajust the circuit to give more max distortion, but that will of course give more distortion at lower levels but also much more at very high levels.
If placed after a source, you would always get the desired distrtion level atthe peaks of the music, no matter the overall sound pressure level at the speakers.
The Aphex exciter circuit is moch more complex, and introduces different kinds of distortion, and I think if placed before the power amp you'll have the same issue.
Then of course why not just place it after the source .... well not so easy i a home theather setup, as the source will go digitally into the receiver or processor.
I realize that my headline for this thread was not good at all, as it has now turned into a long row of postings on purity of sound reproduction, what harmonics actually are, and how to tune a piano or a guitar!
My intention was a discussion on how to actually go about creating someting like the SSL Fusion, Vintage Drive, the circuit needed, different solutions, schematics, actual experience with such circuits etc. Only two responses to that; the H2 circuit by Nelson Pass, and the link to the Aphex Aural Exciter.
I have now Sim'ed the H2 circuit. A very simple and clever little circuit. It more or less does what it says, produceses primarily H2 distortion, but also a little 3'rd and 4'th. The circuit (as also described by Mr. Pass) is a little fiddly to dial in to the wanted distortion spectra. Also I realize that a placement in the chain just before the power amp, is not really the best, as it will very much depend on the "size" of the amp, how much distortion you'll actually get.
The H2 circuit will give lower distortion al low levels and higher towards higher levels of input. Meaning that if you have an input sensivity of say 0.775 V for full output, then you are likely to get to the max distortion level much more often on a 50W amp, than on a 300W amp. You could of course ajust the circuit to give more max distortion, but that will of course give more distortion at lower levels but also much more at very high levels.
If placed after a source, you would always get the desired distrtion level atthe peaks of the music, no matter the overall sound pressure level at the speakers.
The Aphex exciter circuit is moch more complex, and introduces different kinds of distortion, and I think if placed before the power amp you'll have the same issue.
Then of course why not just place it after the source .... well not so easy i a home theather setup, as the source will go digitally into the receiver or processor.
We can change the thread title for you if you like.
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