Harmonics occur naturally in musical sounds. They are what makes musical one musical note sound "rich" rather than "thin".
Each musical instrument has a harmonic signature that makes it recognisable to us.
When an amplifier distorts this harmonic pattern, it can either make the sound different - or, unpleasant.
We normally test with a single (sine wave) frequency, and check that no other frequencies are generated.
Each musical instrument has a harmonic signature that makes it recognisable to us.
When an amplifier distorts this harmonic pattern, it can either make the sound different - or, unpleasant.
We normally test with a single (sine wave) frequency, and check that no other frequencies are generated.
One more try...
Eric Larson wasn't wrong in any respect, but let me try some more explanation:
Say you have a sound wave of some frequency. The favorite note for tuning instruments is an "A" of frequency 440 hz. Also called "A-440." The harmonics of that are frequencies that are integer multiples of that frequency, 2 x 440, 3 x 440, 4 x 440, etc.
giving 880 hz, 1320 hz, 1760 hz, etc. These would specifically be referred to as the second harmonic, third harmonic, fourth harmonic, etc. The original frequency is usually referred to as the "fundamental" although it is also the first harmonic.
If there is something about the system that is prone to oscillating at one of those harmonic frequencies, it may be driven to do so by the mere existence if the fundamental frequency.
How about a piano? It has an A at 440 hz. The next A up the scale, one octave away, is A 880 (so, you get what an octave is?). Since the peaks of the 440 hz. sound wave occur exactly at the same time as every other peak of the 880 hz. , the sound waves from the lower string tend to make the upper string vibrate at its fundamental frequency, 880 Hz. That's why when you push the damper pedal down on the piano and play one note, you hear others joining in to make a richer sound that consists of the fundamental plus other harmonics.
Now, instruments all tend to have harmonics that are naturally occurring as a result of how they are made. That's why an A on a piano sounds different than an A from an oboe. That's because of the differing amplitude of each harmonic produced by the two different instruments.
Harmonic distortion is the distortion (difference between the output signal and input signal) that is due specifically to the harmonics that the amplification system introduces to the signal. Obviously it "shouldn't" introduce any. But all electronic systems introduce some. And as you read more about all this stuff, you'll find that some harmonics are thought to be more naturally pleasing to the ear than others.
As an aside, note that a "pure" frequency consists of nothing other than a sine wave. Exactly. And considering that, you'll realize that a square wave has tons of harmonics.
Eric Larson wasn't wrong in any respect, but let me try some more explanation:
Say you have a sound wave of some frequency. The favorite note for tuning instruments is an "A" of frequency 440 hz. Also called "A-440." The harmonics of that are frequencies that are integer multiples of that frequency, 2 x 440, 3 x 440, 4 x 440, etc.
giving 880 hz, 1320 hz, 1760 hz, etc. These would specifically be referred to as the second harmonic, third harmonic, fourth harmonic, etc. The original frequency is usually referred to as the "fundamental" although it is also the first harmonic.
If there is something about the system that is prone to oscillating at one of those harmonic frequencies, it may be driven to do so by the mere existence if the fundamental frequency.
How about a piano? It has an A at 440 hz. The next A up the scale, one octave away, is A 880 (so, you get what an octave is?). Since the peaks of the 440 hz. sound wave occur exactly at the same time as every other peak of the 880 hz. , the sound waves from the lower string tend to make the upper string vibrate at its fundamental frequency, 880 Hz. That's why when you push the damper pedal down on the piano and play one note, you hear others joining in to make a richer sound that consists of the fundamental plus other harmonics.
Now, instruments all tend to have harmonics that are naturally occurring as a result of how they are made. That's why an A on a piano sounds different than an A from an oboe. That's because of the differing amplitude of each harmonic produced by the two different instruments.
Harmonic distortion is the distortion (difference between the output signal and input signal) that is due specifically to the harmonics that the amplification system introduces to the signal. Obviously it "shouldn't" introduce any. But all electronic systems introduce some. And as you read more about all this stuff, you'll find that some harmonics are thought to be more naturally pleasing to the ear than others.
As an aside, note that a "pure" frequency consists of nothing other than a sine wave. Exactly. And considering that, you'll realize that a square wave has tons of harmonics.
Hello,
take a look at here, it's explained the simple way : http://www.harmony-central.com/Guitar/harmonics.html
Basically harmonics are the differences,in frequency,between the original signal (called fundamental) and the tested signal.
So if the tested sinewave is equal to the fundamental, there are no harmonics; if the tested sinewave has a frequency that is the double of the fundamental frequency , it is called second harmonic; if the tested sinewave has a frequency that is the three times of the fundamental frequency , it is called third harmonic and so on.
To go more deeper, take a look at FOURIER THEORY : everything started from it!!
Regards
Claudio
take a look at here, it's explained the simple way : http://www.harmony-central.com/Guitar/harmonics.html
Basically harmonics are the differences,in frequency,between the original signal (called fundamental) and the tested signal.
So if the tested sinewave is equal to the fundamental, there are no harmonics; if the tested sinewave has a frequency that is the double of the fundamental frequency , it is called second harmonic; if the tested sinewave has a frequency that is the three times of the fundamental frequency , it is called third harmonic and so on.
To go more deeper, take a look at FOURIER THEORY : everything started from it!!
Regards
Claudio
Bricolo said:
Put 1 kHz sinus wave signal at the input of an amplifier. What do you get at the output? Of course 1 kHz sinus (but a little bit more voltage) ....but... also 2 kHz added and 3 kHz added and 4 kHz added and 5 kHz added etc. This additional tones are added the original input signal. Do you see the pattern? x2, x3 x4 x5 x6 x7 times the input frequency. This additional tones are harmonics to the basic tone. 1% harmonic distorion means that all of the harmonic tones has 1% of the basic signal's amplitude.
Why do you get overtones? The amplifier in not linear. Output (not =) Input*Gain
OK, I'll take a stab at it 
Mathematics shows us that any waveform you can dream up
can be shown to be made up of various frequencies, each with
its own amplitude and phase. This is called Fourier analysis.
ANY wave form.
If the wave form is repetitive forever, then the spectral
composition will be made up of the frequency of repetition
plus multiples of that frequency.
If the wave is a pure distortionless sine wave, then there is
only that frequency. This makes a convenient test signal,
since if the amplifier distorts, the output will not be a pure
sine wave and there will be additional frequencies, all
multiples of the fundamental sine wave.
Even order harmonics, 2nd, 4th, 6th, etc, represent
distortion which is not symmetric from + to - about the "0"
point, and odd order harmonics, 3rd, 5th, etc, are distortions
which are symmetric above and below the zero point of the
wave.
Distortion analyzers remove the fundamental with a filter
and leave you the harmonics to look at.
Does that help?
Mathematics shows us that any waveform you can dream up
can be shown to be made up of various frequencies, each with
its own amplitude and phase. This is called Fourier analysis.
ANY wave form.
If the wave form is repetitive forever, then the spectral
composition will be made up of the frequency of repetition
plus multiples of that frequency.
If the wave is a pure distortionless sine wave, then there is
only that frequency. This makes a convenient test signal,
since if the amplifier distorts, the output will not be a pure
sine wave and there will be additional frequencies, all
multiples of the fundamental sine wave.
Even order harmonics, 2nd, 4th, 6th, etc, represent
distortion which is not symmetric from + to - about the "0"
point, and odd order harmonics, 3rd, 5th, etc, are distortions
which are symmetric above and below the zero point of the
wave.
Distortion analyzers remove the fundamental with a filter
and leave you the harmonics to look at.
Does that help?
This sound to me like producing harmonics is the only kind of "distorsion" a amplifier circuit is able to produce. A question, i don´t know if its stupid, but i really don´t understand: what is about mixing the signals? Every Radio employs circuits where one frequency is put in, and mixed with a second frquency and out comes the positive and negative difference (plus the original frequencys) so if i don´t go the usual way to put 1 kHz in the amp and look ´how much 2kHz , 3kHz ... comes out, but i put in 1kHz and 900Hz and look for what i suspect comes out : 100Hz and 1100Hz, 900Hz and 1kHz) ???
Harmonics
Here is a link to a the Physics Classroom. In lesson 4 there is a section on harmonics.
This is simplified but it is helpful.
http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/soundtoc.html
Cheers
Craig Ryder
Drop me an email for an outline of Online diytube electonic resources.
Here is a link to a the Physics Classroom. In lesson 4 there is a section on harmonics.
This is simplified but it is helpful.
http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/soundtoc.html
Cheers
Craig Ryder
Drop me an email for an outline of Online diytube electonic resources.
Ok, my thought is, every natural sound from any instrument has a lot of harmonics. A little less or more (0,01 - 1 % ) wouldn´t change the sound much. But this " intermodulation distortion " would cause a serios destruction of sound. Why is there no data how much of this much worse kind of distorsion is produced by an analog cicuit? harmonic distorsion, 1/2% , 1% says nothing. How much mixing the signal is there?
Is this intermodulation stuff the reason why a cicuit with less active devices sounds better?
Is this intermodulation stuff the reason why a cicuit with less active devices sounds better?
till said:
In reality the intermodulation distortion caused in amplifiers is very small, as compared to that present in a mixer. To produce high levels of Intermod distortion, you could put a single diode on the output of the amplifier, thus creating a diode mixer (A simple RF mixer is 1 diode!). If you can imagine what the output would look like on a scope, with one half of the signal missing, this would contain high intermod distortion. (And high harmonic distortion)
In a perfect linear amplifier, the Intermod distortion would be 0, that is you could send in two sine waves, say 900Hz and 1000Hz into the amp, all you would get out would be 900Hz, and 1000Hz. The same would be true for harmonic distortion, nothing but the origional signal would come out.
In reality, No amplifier is perfectly linear, so there are small ammounts of IMD, as well as harmonic distortion. The Intermod and harmonic distortion should be roughly proportional (They are both caused by the nonlinearities of the amplifier). So, that is if you increase the harmonic distortion, you will increase the Intermod as well. It's a pretty simple to measure harmonic distortion, so that's the number often used for comparisons of amplifiers.
-Dan
yes i understand this. but the comparison has only some value if harmonic distorsion and imd is absolutely same way proportional in both amps compared.
All i want to say is, this intermodulation distorsion is eventualy the much better parameter to compare 2 amps. Why is it not measured apart from normal harmonic dist. ? It would be very intersting to knor differences of this imd of different amps.
Nelson Pass said:OK, I'll take a stab at it
Mathematics shows us that any waveform you can dream up
can be shown to be made up of various frequencies, each with
its own amplitude and phase. This is called Fourier analysis.
ANY wave form.
If the wave form is repetitive forever, then the spectral
composition will be made up of the frequency of repetition
plus multiples of that frequency.
If the wave is a pure distortionless sine wave, then there is
only that frequency. This makes a convenient test signal,
since if the amplifier distorts, the output will not be a pure
sine wave and there will be additional frequencies, all
multiples of the fundamental sine wave.
Even order harmonics, 2nd, 4th, 6th, etc, represent
distortion which is not symmetric from + to - about the "0"
point, and odd order harmonics, 3rd, 5th, etc, are distortions
which are symmetric above and below the zero point of the
wave.
Distortion analyzers remove the fundamental with a filter
and leave you the harmonics to look at.
Does that help?
thanks a lot, Nelson
PS: have you recieved my mail?
Nelson Pass said:OK, I'll take a stab at it
Mathematics shows us that any waveform you can dream up
can be shown to be made up of various frequencies, each with
its own amplitude and phase. This is called Fourier analysis.
ANY wave form.
If the wave form is repetitive forever, then the spectral
composition will be made up of the frequency of repetition
plus multiples of that frequency.
If the wave is a pure distortionless sine wave, then there is
only that frequency. This makes a convenient test signal,
since if the amplifier distorts, the output will not be a pure
sine wave and there will be additional frequencies, all
multiples of the fundamental sine wave.
Even order harmonics, 2nd, 4th, 6th, etc, represent
distortion which is not symmetric from + to - about the "0"
point, and odd order harmonics, 3rd, 5th, etc, are distortions
which are symmetric above and below the zero point of the
wave.
Distortion analyzers remove the fundamental with a filter
and leave you the harmonics to look at.
Does that help?
I'm glad you posted here, Nelson
It's your fault if I've posted this topic
I explain: in your zenamp.pdf, you wrote (at the right bottom of page 4)
Fig 6 shows the harmonic distortion curve from 10 milliwatts to 20 watts at 1 Khz and 8 ohms. Below 10 watts the distortion is purely second harmonic.
but Fig 6 only shows a distortion/power graph
how can you conclude it's 2nd, 3rd or 4rd harmonic, looking the curve?
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