"AH"?
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Why Don't High SINAD Receivers Exist?
- Thread starter thunderchicken
- Start date
A bit baffling to read that from someone with as much experience as you. Yes, you may be able to 'hide' SINAD's 'N' component under the room's noise floor but AFAIK, there is no device/way to 'hide' the HD part. Or even more generic: AFAIK, the only distortion that truly acts like a (hide-able) noise-floor is, well, the noise floor
HD simply 'infects' your signal top down, it does not matter if you listen at '3db' or '300dB'. Yes, at lower volumes the HD %level might also be lower. But it might also be higher. Or you might get completely different HD 'coloration' at the same %level. Very doubtful gains that way. If any.
Here's an easy analogy for HD: when playing a video 5x faster, its 5x faster audio will sound 'colored' with a higher pitch. That's a simple form of clock distortion. And no matter the listening volume, the ~exact same higher pitch 'coloration' is there.
HD works ~same as that clock distortion, it 'colors' the sound. From the first dB of volume to the last.
Yes, a lot of "usually" and "maybe" in my post but that's the state of distortion science. Here's the very short takeaway: the HD may or may not be audible but one thing is for sure, you can't hide/undo it! The HD will always reach your ears and always at the exact measured level.
Or put in another way: the entire HD in it's whole 'glory' is imprinted in every single sound-wave that reaches your ears.
P.S.
uf, really didn't want to talk about that offtopic distortion. I blame it on you @peng
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A bit baffling to read that from someone with as much experience as you.
Yes, you may be able to 'hide' SINAD's 'N' component under the room's noise floor but AFAIK, there is no device/way to 'hide' the HD part. Or even more generic: AFAIK, the only distortion that truly acts like a (hide-able) noise-floor is, well, the noise floor
HD simply 'infects' your signal top down, it does not matter if you listen at '3db' or '300dB'. Yes, at lower volumes the HD %level might also be lower. But it might also be higher. Or you might get completely different HD 'coloration' at the same %level. Very doubtful gains that way. If any.
Those HD components may or may not be audible but one thing is for sure: you can't hide/undo them! And the'll always reach your ears at their 'best' level.
Here's a (potentially) useful and very easy analogy for HD: when playing a video 5x faster, its 5x faster audio will sound 'colored' with a higher pitch. That's a simple form of clock distortion. And no matter the listening volume, the ~exact same higher pitch 'coloration' is there.
HD works ~same as that clock distortion, it 'colors' the sound. From the first dB of volume to the last.
P.S.
uf, really didn't want to talk about that offtopic distortion. I blame it on you @peng
I am here to learn, so thanks. However, I don't follow you in this case, as I never meant to say noise floor would hide HD, of course not so we are actually in agreement on that point. My point is, if you look a the FFT, 32 tones test etc., and you see none of the HD, be it 2nd, 3rd, 5th order are all at 75 dB below the foundamental frequency, then I, for one would not be able to hear it in my room that has at least 23 dB of noise between 20 and 20,000 Hz if the SPL I listen to is not higher than 980dB (75+23). So again, it is not hidden, but I would not be able to distinguish the HD signal from the background noise. In fact, as soon as I turned off the HVAC, I felt my room was silent, yet REW/Umik-1 tell me far from it, as it measured 20 to 25 dB across the audio band.
It is like if I play some music and listen to say 80 dB level (way too loud for me) at volume position -5 for a little while, then I turn the volume down gradually until I cannot hear anything. I did that a few times and I know by the time the volume position reached -79 I definitely could not hear the music. And as I think I mentioned, I know at least in theory, if my room is much quieter, like approaching that in an anechoic chamber then I should be able to hear the music even with volume position at minimum but any DH contents would have been blended with noise of the devices in use, not the noise floor of the room in that scenario.
So it has nothing to do with my experience as such, but the applicable theories. (science..)
PS HD your referred to is harmonic distortions right? So the 2nd harmonic of a 1000 Hz signal is 2000 Hz, so on and so forth. If the 2nd harmonic created by the electronic devices in the audio chain, is say -75 dB, and the foundamental is say at 90 dB, the spl due to the 2nd harmonic would be 90-75 = 15 dB. So I don't follow what you meant by "HD simply 'infects' your signal top down, it does not matter if you listen at '3db' or '300dB'."
I should also mention that at low output level, THD of an amp, such as the AVR-X4700H would tend to be higher, say even 10%, that is -20 dB. But 20 dB below a low spl listening level of say 40 dB, is still very low for a room with even just 20 dB noise in the audio band.
I hope we don't have a different understanding of harmonic distortions. (Fourier is key in the understanding of it)
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glad to hear that it was (at least partially) a misunderstanding. But now I'm not sure if we have any disagreements left to discuss
Your PS seems to indicate that we do. I changed my post after you quoted, maybe that version is more clear?
Trying again.
The frequency domain THD-graph might be quite misleading: most people see those 2-3-x harmonics and their mental-image is that of "extra sounds" that can be heard at -75db or whatever. Or they imagine the 2-3-x harmonics as forming a sort of audible noise floor. AFAIK, the THD-level is not some sort of "noise floor level".
Just look at the same THD graph in the time domain. The original 1khZ sinewave looks 'perfect' and the distorted one looks 'deformed'. There are no 'extra sounds' in there, the distortion harmonics are an integral part of the deformed sinewave.
A bit out of ideas here
. Maybe this or this helps for someone with EE knowledge?! Like this quote "Total harmonic distortion (THD) ... is due to harmonics _in_ the signal"
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glad to hear that it was (at least partially) a misunderstanding. But now I'm not sure if we have any disagreements left to discuss
Your PS seems to indicate that we do. I changed my post after you quoted, maybe that version is more clear?
Trying again.
AFAIK, the HD level cannot be seen as a "volume level" or "noise floor level". The frequency domain THD-graph is actually quite misleading, most/many people see those 2-3-x harmonics and imagine that they are some "extra sounds" that you hear at -75db or whatever. Or imagine that the 2-3-x harmonics form a sort of audible noise floor.
Look at the same THD graph in the time domain. The original 1khZ sinewave looks 'perfect' and the distorted one looks 'deformed'. There are no 'extra sounds' in there, the distortion harmonics are an integral part of the deformed sinewave.
A bit out of ideas here
I does seem like we have a different understanding, I think.... I know my understand is correct, not because I am an EE, but also because I have studied communication theory that involves Fourier series, transforms (such as the FFT).
I have read lots of harmonics related articles, and there is nothing in those links that contradicts my understanding..
The "deformed" (I take it you meant non sinuisodal), waveform is in fact an infinite series of sinusoidal waveform of the fundamental, and harmonics of the fundamental. If you add the point on wave values of say a 1000 Hz, 2000 Hz, 3000 Hz sine wave together you will get a deformed looking wave. For musical instrument, I am sure you know, has a lot of harmonic contents but they would not sound objectionable. When reproduced by the audio signal path of electronics amplification, the electronic devices (loudspeakers too obviously) add their own and are not not pleasant sounding to our ears because while they are still harmonics of the fundamental, they are not what the same harmonics the instrument produced, but are extra ones.
There is good reason for THD to be stated in - X dB, or SINAD (that includes noise) in X dB, it is to make it easier to relate to threshold of audibility.
Please take a read of Benchmark's below:
https://benchmarkmedia.com/blogs/ap...preting-thd-measurements-think-db-not-percent
and note it says: "When distortion reaches 1% it is just 40 dB lower than the music. When distortion reaches 0.1% it is 60 dB lower than the music. When distortion reaches 0.01% it is 80 dB lower than the music. Obviously the 40 dB, 60 dB and 80 dB figures are easier to understand than 1%, 0.1% and 0.01%. "
As you mentioned before, this may be off topic though I think it is still "on" topic until it isn't if we keep going and we may be getting there
. So if we disagree then I am totally okay with agreeing to disagree.But let me try one more time before we move on:
In your first link, if you go to chapter 13 (yours link to chapter 11), and go right to the bottom of the page:
http://www.dspguide.com/ch13/4.htm under the last section the "The Fourier Series" you will see the table below that show the component harmonic frequencies and their magnitude. You can see how the pulse train (rectangular wave) can be reconstructed with harmonics, the example use only the first 14 harmonics, to get to the original it need a lot more, but anyway, in the table, you can see that the 3rd harmonic is only 0.2 V and this is a very ugly waveform, of a 1 kHz fundamental.
A music signal waveform could look very complex/ugly but it is still just a series of harmonics of fundamental sine wave. Obviously the harmonics of a pure square, triangular or whatever "deformed", i.e. non sinusoidal waveform are not "distortions" if they are produced by musical instruments of electronics if produced perfectly, otherwise they would be distortions if created by the electronics such as amplifiers. But harmonics are still harmonics, that are harmonics of the fundamental frequency of the original signal, as such they are sine waves at multiples of the fundamental frequency.
Thank you for an interesting discussion.
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3dbinCanada
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That is an interesting flaw you found in there.
But here's something even more interesting: I didn't (want to) say that TVs sound bad. Or good. Also didn't say that AVRs sound bad. Or good. Also no "golden ears" or other ears in my posts besides a few "try this comparison yourself".
My AVR_SQ=TV_SQ argument is mostly a tech/engineering point of view. It's just a simple '=' argument and should be independent of any good/bad implications. But there are of course other implications, like the (at least) partially true: an AVR is not needed since the TV can output the same SQ into external amps/speakers.
Here's someone who does the unusually far-out argument waaaaaay better than me. For anyone who likes their standup comedy to be a lot more than simple ha-ha, it should be quite a delight.The 'flaw' you found is still a beauty and it's definitely easy and (somewhat) fair to interpret my '=' like that. I was actually curious how many will cry on that '=' with "you insulted my precious AVR, I hate you" (like 3db did). And while 'secretly' cheering for someone to use a "my TV is better" angle, I had very low hopes. Thank you for that good surprise! And a surprisingly balanced 'cry-score'
It's all just a human-nature thing, it happens (almost always) when you put an unusually far-our argument on the table. Many people who don't like it (and/or don't understand it), will have a very butt-hurt reaction. Some will even put their own stuff into the original argument and start demonstrating how that stuff is wrong. A psycho form of yelling/arguing with yourself that I sometimes find entertaining. Sometimes not.
But that's pretty much how I 'became' all sorts of 'scary people' in this thread: audiophile, DBT-hater, deaf and many other things. Sorry to disappoint: just an engineer who sometimes finds psychology fun. Danger warning: that is only armchair psychology at best!
Or an even more far-out idea: forget imaginary audiophiles, DBTs and all other off-topics and (re)start talking about "high SINAD
Nothing like putting words in someone's mouth.. Who said anything about hating you? Enough of your armchair psychology. .wrong there too Im afraid.
You keep referring to engineering but ignore the most important aspect.... (warning, spoiler alert, you won't like what you hear) ... the sound. For some strange reason you keep avoiding the sound telling everyone here that its not about the sound but just the engineering. Furthermore, you keep discounting real life experience with specifications yet you never put in a correlatation of specs to sound. Why does sound quality not matter to you? Are you afraid of DBT? Is this why you shun them so fiercely?
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3dbinCanada
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Audioholics forum.
I does seem like we have a different understanding, I think.... I know my understand is correct, not because I am an EE, but also because I have studied communication theory that involves Fourier series, transforms (such as the FFT).
I have read lots of harmonics related articles, and there is nothing in those links that contradicts my understanding..
The "deformed" (I take it you meant non sinuisodal), waveform is in fact an infinite series of sinusoidal waveform of the fundamental, and harmonics of the fundamental. If you add the point on wave values of say a 1000 Hz, 2000 Hz, 3000 Hz sine wave together you will get a deformed looking wave. For musical instrument, I am sure you know, has a lot of harmonic contents but they would not sound objectionable. When reproduced by the audio signal path of electronics amplification, the electronic devices (loudspeakers too obviously) add their own and are not not pleasant sounding to our ears because while they are still harmonics of the fundamental, they are not what the same harmonics the instrument produced, but are extra ones.
There is good reason for THD to be stated in - X dB, or SINAD (that includes noise) in X dB, it is to make it easier to relate to threshold of audibility.
Please take a read of Benchmark's below:
https://benchmarkmedia.com/blogs/ap...preting-thd-measurements-think-db-not-percent
and note it says: "When distortion reaches 1% it is just 40 dB lower than the music. When distortion reaches 0.1% it is 60 dB lower than the music. When distortion reaches 0.01% it is 80 dB lower than the music. Obviously the 40 dB, 60 dB and 80 dB figures are easier to understand than 1%, 0.1% and 0.01%. "
As you mentioned before, this may be off topic though I think it is still "on" topic until it isn't if we keep going and we may be getting there
But let me try one more time before we move on:
In your first link, if you go to chapter 13 (yours link to chapter 11), and go right to the bottom of the page:
http://www.dspguide.com/ch13/4.htm under the last section the "The Fourier Series" you will see the table below that show the component harmonic frequencies and their magnitude. You can see how the pulse train (rectangular wave) can be reconstructed with harmonics, the example use only the first 14 harmonics, to get to the original it need a lot more, but anyway, in the table, you can see that the 3rd harmonic is only 0.2 V and this is a very ugly waveform, of a 1 kHz fundamental.
A music signal waveform could look very complex/ugly but it is still just a series of harmonics of fundamental sine wave. Obviously the harmonics of a pure square, triangular or whatever "deformed", i.e. non sinusoidal waveform are not "distortions" if they are produced by musical instruments of electronics if produced perfectly, otherwise they would be distortions if created by the electronics such as amplifiers. But harmonics are still harmonics, that are harmonics of the fundamental frequency of the original signal, as such they are sine waves at multiples of the fundamental frequency.
View attachment 72407
Thank you for an interesting discussion.
Could it be possible that you’re both saying the same thing. It does “color” the sound however is coloration is at a very low Db therefore it doesn’t have a huge effect
I also think that we are largely saying ~the same thing. And could very well be that I am exaggerating the diffs.
Yes the HD 'coloration' can be small enough so it's not audible. But not because it "is at a very low dB" level somewhere 'under' the signal but because it's a very small 'deformation' of the signal itself.
I would not go into 'audibility' though, or at least not from the beginning. That is a separate and giant 'blackhole' by itself, maybe we can keep it 'closed' for now?!
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We agreed it could be inaudible if low enough, but like he said the difference is (I think), he said "not because it "is at a very low dB" level somewhere 'under' the signal "and what I am saying is "when the distortion is X (X can be 100, 50, even 10 dB) dB below the fundamental frequency, it will not be audible if you turn the volume low enough such that the sound pressure level at the listening position is below the room's noise level, that is the "sound" due to the noise in the room when the music is not playing. I listed some examples before but I'll do it again here:
Room noise floor with no music playing, say even the amps are power off, no tv no nothing...................23 dB 1000 to 6000 Hz (that is a very quiet room)
Now play some music and set the volume so that the spl at the listening position is....................................75 dB avg, 95 dB peak
In this example, if the THD (total) is -70 dB, SINAD will be somewhat higher depending on the devices because SINAD = THD+N numerically.
so during the peak moments, the music could be at 90 dB (maximum in this example), but the harmonic distortion components in total will be at :
95 - 75 = 20 dB level, and that is 3 dB below the room's noise level so the listener will not be able to distinguish whether the "sound" was noise or distortions from the electronic devices playing through the loudspeakers which also have their own distortions, typically in much higher %/dB than the electronic devices. The sound of the distortions will still be there, dogs and cats may be able to sort what what's noise, what's the 2nd, 3rd, 4th, 5th.... harmonics from the dac, premap, amp, speaker's distortions.
The numbers I used are just an example, so if you pick different numbers, say at such low level the amp's THD is 5%, or -26 dB, then 90-26 dB = 64 dB, in that the distortions will be highly audible as 64 dB from the distortions is 64-23 = 41 dB above the room's noise floor level.
Then in this second numerical example, if you turn the volume way down, at some point the very high distortions of -26 dB would again sink below the room's noise floor and disappear to the ears.
To make another point clear, consider the following:
1) Let's assume there is an instrument that produce a tone at 1,000 Hz and the waveform is perfectly triangular, so it is not a "Pure_tune", but it is "the sum of a number of harmonically related sinusoidal components".
2) Now further assume we record this tone, play it through a super hi-fi system including the speakers that has no distortions, no noise, that is THD+N = - infinity or SINAD = infinity.
In this example we are playing a non pure tone so it has lots of harmonics, but no distortions, the harmonics are naturally produced by the musical instrument.
3) Now assume the same as 1) and 2) above except if the hi-fi system would produces harmonic "distortions" such that THD = - 100 dB, or 0.001%. Note: ignore noise just for simplicity for demo purposes.
In this case 3), the same 1000 Hz being play will have not only the natural harmonics that are obviously not considered "distortions", but also have the harmonic components produced by the hi-fi system such that the THD+N is at the -80 dB level. In this case, you will have the following observations:
1) To use lashto's term, the 1000 Hz triangular waveform will now be slightly deformed though it may not be highly visible to the eyes at such low level (0.01%), it would be highly visible if THD is higher, say 10% (-20 dB)
2) Even at just 0.01%, depending on the profile of the harmonic distortions, that is % of the individual harmonics that include 2nd, 3rd,.......9th 11th etc. etc.. depending on one's hearing (this is where I agreed with lashto too, that we wouldn't want to get into), it may or may not be audible and it would again, still depend on the listening spl at the seating position, as well as the room's noise floor.
So again, we are sort of saying the same thing but it does appear our concept/understanding of "harmonics/harmonic distortions" are quite different.
Thanks @peng, your EE input is highly welcome cause I am just an E. I can follow math but EE-math is not something I do for a living.
Kinda preparing a bigger post with a larger psycho-acoustics perspective. It looks like we still have somewhat different views on that THD+N level being "below music". I still think that the "below" only applies to the N but not to the HD.
And I definitely want to know if I'm right or wrong. So, expert EE input still highly needed.
And we are all so off-topic here, I would say that this thread is at 120% THD now
Kinda preparing a bigger post with a larger psycho-acoustics perspective. It looks like we still have somewhat different views on that THD+N level being "below music". I still think that the "below" only applies to the N but not to the HD.
And I definitely want to know if I'm right or wrong. So, expert EE input still highly needed.
And we are all so off-topic here, I would say that this thread is at 120% THD now
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There is no Learning without BendingOh, no, that would be totally audible.
. Let's see, maybe I will learn something. Trying to put my HD thoughts in order now
There is no Learning without Bending
Let's see, maybe I will learn something. Trying to put my HD thoughts in order now
Thanks again for engaging, and again we don't have to agree on everything the discussion has been at least interesting and enjoyable.
Now back to the original topic, the OP, in his first post seemed to have suggested he would consider 100 dB as "High".
In that case, I would say the AVR-X3600H could be considered an AVR capable of high SINAD, arguably speaking, because on more than one occasion Amir did mention 103 dB was achieved.
Such as:
https://www.audiosciencereview.com/...ds/denon-avr-x3600h-av-receiver-review.12676/
"When I first ran this test, I had set the sample rate to 48 kHz by accident and SINAD, for the first time in any video product, went up to 103 dB! Sadly and for unknown reason, setting it to 44.1 kHz increased second harmonic causing SINAD to drop to 99 dB. Still excellent though for an AVR: "
"Notice that even with 44.1 kHz we get a SINAD of 103 dB. The reason that is higher than the dashboard is because the digital input is lower value in this test than full 0 dB used in the dashboard."
"Notice slightly better performance for 48 kHz as I indicated (in red). Since majority of video content is produced at 48 kHz and multiples of it, that is not a bad thing although you could argue when you want the best performance, it would be for music content."
So it may be fair to say the X3600H would fit in Amir's green bucket DACs. That's probably all we can ask, considering an AVR is a compromised device, with so many things jammed in one box thereby trading something for versatility.
I wonder if anyone will really read this monster post. Let's see. And let's see who learns what here @peng . Hopefully we all do.I does seem like we have a different understanding, I think.... I know my understand is correct, not because I am an EE, but also because I have studied communication theory that involves Fourier series, transforms (such as the FFT).
I have read lots of harmonics related articles, and there is nothing in those links that contradicts my understanding..
The "deformed" (I take it you meant non sinuisodal), waveform is in fact an infinite series of sinusoidal waveform of the fundamental, and harmonics of the fundamental. If you add the point on wave values of say a 1000 Hz, 2000 Hz, 3000 Hz sine wave together you will get a deformed looking wave. For musical instrument, I am sure you know, has a lot of harmonic contents but they would not sound objectionable. When reproduced by the audio signal path of electronics amplification, the electronic devices (loudspeakers too obviously) add their own and are not not pleasant sounding to our ears because while they are still harmonics of the fundamental, they are not what the same harmonics the instrument produced, but are extra ones.
There is good reason for THD to be stated in - X dB, or SINAD (that includes noise) in X dB, it is to make it easier to relate to threshold of audibility.
Please take a read of Benchmark's below:
https://benchmarkmedia.com/blogs/ap...preting-thd-measurements-think-db-not-percent
and note it says: "When distortion reaches 1% it is just 40 dB lower than the music. When distortion reaches 0.1% it is 60 dB lower than the music. When distortion reaches 0.01% it is 80 dB lower than the music. Obviously the 40 dB, 60 dB and 80 dB figures are easier to understand than 1%, 0.1% and 0.01%. "
As you mentioned before, this may be off topic though I think it is still "on" topic until it isn't if we keep going and we may be getting there
But let me try one more time before we move on:
In your first link, if you go to chapter 13 (yours link to chapter 11), and go right to the bottom of the page:
http://www.dspguide.com/ch13/4.htm under the last section the "The Fourier Series" you will see the table below that show the component harmonic frequencies and their magnitude. You can see how the pulse train (rectangular wave) can be reconstructed with harmonics, the example use only the first 14 harmonics, to get to the original it need a lot more, but anyway, in the table, you can see that the 3rd harmonic is only 0.2 V and this is a very ugly waveform, of a 1 kHz fundamental.
A music signal waveform could look very complex/ugly but it is still just a series of harmonics of fundamental sine wave. Obviously the harmonics of a pure square, triangular or whatever "deformed", i.e. non sinusoidal waveform are not "distortions" if they are produced by musical instruments of electronics if produced perfectly, otherwise they would be distortions if created by the electronics such as amplifiers. But harmonics are still harmonics, that are harmonics of the fundamental frequency of the original signal, as such they are sine waves at multiples of the fundamental frequency.
View attachment 72407
Thank you for an interesting discussion.
Agree with ~all you say above, it's all good info. But I 50% disagree with that Benchmark quote.
"When distortion reaches 0.01% it is 80 dB lower than the music. Obviously the 40 dB, 60 dB and 80 dB figures are easier to understand than 1%, 0.1% and 0.01%. "
For the N part of the THD+N or SINAD distortion, I agree that the dB value is definitely the most intuitive/useful.
However, for the HD part I pretty much disagree completely: to me the % value is most intuitive and the dB value (potentially) confusing.
And IIRC, THD was originally thought as a % number.
At this time, I assume most people actually got a good understanding of my points and @peng 's.
So I'll just throw a few more examples/analogies/views, just to see what sticks. That is, I will just repeat the ~same thing over and over. Sue me
I'd like to know which analogy people find most useful. And should be useful for me too, to kinda re-organize the HD-info in my own head. And there is still a chance that I got some things wrong. At least some of the stuff below might be just "my view" and not necessarily 100% correct.
One view: about the THD number as either dB or %
The THD dB value I see as confusing because it creates the impression that the THD dBs are related the sound level dBs (similarly to the way noise floor dBs are related to the sound level dBs). The % value does not carry that dBs-to-other-dBs confusion. But many also interpret a value of 0.01% THD to mean that some 'lower' 0.01% part of the signal is distorted and the rest is ok. I think it's much a better analogy to see 0.01% THD as a 0.01% 'deformation' of the entire signal.
A potentially useful graph: Green is the original signal, Blue is a sample 3rd harmonic and Red shows how the original signal will look after adding the 3rd harmonic into it: it's 'deformed'. And it's not deformed at the top or bottom, it's fully deformed.
And another one showing how a pure sine-wave is 'deformed' by (idealized, even-order) HDs until it becomes a square-wave. Fully deformed again.
And another one showing how a pure synth signal looks after you put a guitar's HDs into it (this one is just a visual aid, not necessarily 100% correct).
A different view: sort of a big simplification/abstraction which might work visually. And yes, I'll try to describe a graph in words
Let's take an original signal at 90dB volume and plot it on a THD-freq graph as a sort of "music floor" at 90dB. It would be a straight music-floor-line at 90dB.
The N itself would be another straight line at say 20dB (i.e. -70dB under the original). Because the N is best seen as a separate signal and (hopefully 100%) unrelated to the music-floor signal.
I guess @peng that we fully agree up to here.
Here's where we (potentially) part ways.
The question is: how would one plot/draw the THD on this graph? Would it be an extra THD-floor-line, somewhere between the music-floor line and the noise-floor line? Most people do that. Even some audio experts do that (or seem to think that way).
And I think that's just wrong. On such a graph, my best 'visual' representation of the THD would be as 'something' that makes the 90dB music-floor line undulated instead of straight ... whatever that 'undulated' looks like is a another discussion and let's forget it for now.
Mostly because of the above, I think that putting HD and N together in a single number is a pretty bad idea. An opinion I seen a few times from expert EE & acoustics people (sorry, no link/quote). THD+N is ok from a measurements/engineering perspective but if you want to discuss audibility/acoustics, that number it's a useless mashup.
Another view: sort of a gedankedexperiment that should help with the psychoacoustics/neuroscience of HD.
I think the psycho-acoustics give a much better view of HD than the view you get from math & THD graphs. And you made a very helpful mention @peng of the harmonics that are included in any note played by a musical instrument.
So let's say we grab a piano and play a single, 'pure' note like A4 (i.e. a frequency of ~432Hz). And lets assume that we recorded that signal perfectly with no extra distortion. If we analyze/plot it, we'll see the fundamental at 432 Hz and multiple harmonics at 2X, 3X, etc.:
This might just be one of those proverbial "image better than a thousand words". So let's see some of those words:
- First of all, the above graph might be a surprise for some: a 'simple' piano note looks exactly like a THD measurements graph. You have the fundamental at 432Hz and it's HDs at 2x, 3x, etc. It's almost 100% the same as a THD graph. And there is no metaphor/analogy in here, those two graphs are indeed mathematically ~100% same (that's mostly under a big 'AFAIK', anything to correct here @peng?!?).
- The HDs of this simple piano note are seriously high, its THD would be a gruesome >50%. And btw, the HDs of some instruments go much higher than that, even above 100% (for the trumpet IIRC).
To figure out how it'll sound, we can apply the HD-as-a-floor-distortion model to the above piano-note graph. Here are its predictions:
- at >50% THD we should hear a seriously distorted, "aaa, my head hurts" sound. Still somehow recognizable as a piano A4 note.
- we should hear that THD-floor as a sort of high level 'mud' in the A4 sound.
In the case of the trumpet with >100% THD, the HD-as-a-floor-distortion model says that we shouldn't even hear the A4 note fundamental, just some fully distorted HD-floor garbage. But again we don't, we just hear a crystal-clear A4 trumpet note.
Generally, no matter how many HD spikes and no matter how big they are, the human ear will still hear an A4 note. And the (432Hz) pitch of the A4 note will not change at all and it will still be recognizable to our ears as an A4 note/pitch.
This would be my base for saying that the HD-as-a-floor-distortion model is simply Wrong: it predicts that we'll hear lots of 'garbage' but there is none to be heard.
And here's something even more 'strange': with a bit of math and signal-processing it is possible to take the A4/432Hz fundamental out of that recorded piano A4 sound. And we will have a recording of a piano A4 note which only contains its HDs.
What will you hear if you play that HDs-only recording?
...
Take a guess... really curious if someone guesses right here. I surely didn't the first time.
---
Here's the 'strange' answer: you will hear the ~same piano A4 note. We took out the A4 fundamental but our ears still hear it from just its HDs.
This is pretty much my base for saying that the HDs are 'imprinted' into the signal. Actually, according to the above experiment, the HDs are not just 'imprinted' into the signal, the HDs are the signal!
Not sure exactly what is the math/EE view on this but the human ear says it quite clearly: the HDs are the signal.
.....
No idea if anyone will read this to the end but anyway, no more time, gotta stop. Should be enough for a while. More to follow about the real "money question": how do those HDs actually sound to our ears? ... Sometime.
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let's not get ahead of ourselves, I might not be bending that much
. And my opinion of the x3600 and entire Denon 2020 line is still: engineering clusterfuck. Doubt that one will ever bend. Maybe into worse. But definitely a good, enjoyable distortion talk.
Hope you have time to read the above at some point. EE input highly needed.
That's a long post, so let me try to response a little bit at a time. For now, I would point out the fact that you are sort of saying what I said in my own monster length post earlier, that the music instrument produced waveform would look like HD, except please recognize that I also said those are not actually consider HD, they are just H. Harmonics, but not harmonic distortions.
Harmonics are produced from the music instrument itself and it is not distortions, what you see are just the harmonic components of the tone that is not a pure tone (sine wave). I don't know if there is a musical instrument that produce a pure tone. Piano, violin, drums, all produce tones that contains tons of harmonics, but they are not harmonic distortions.
Harmonic distortions came from the reproducing devices, that include the recording devices, media, media player, amplifiers and loudspeackers etc. Those devices fail to reproduce the original signal 100% accurately, and so harmonics (related to the original signal) are added, that's why they are distortions. Are we on the same "wavelength" on this point too?
To summarize this part of our discussion:
1) Of course your A4 note would sound crystal clear, it is not a pure tone so it has lots of harmonics, but not harmonics from "distortions".
2) The harmonic profile of an undistorted A4 note, that is, as played by the real piano, will in fact look like the reproduced signal by a hi-fi system, the difference is that the reproduced one will have all the harmonics of the piano's, plus the additional harmonics created by the reproduction system's devices, from mic to loudspeakers. It is those added harmonics; and because they are harmonics added externally by the devices, we called them harmonic distortions and they could sound irritating if high enough, in % or dB. Emphasis: If the electronic devices can reproduce the original signal, from the recording devices, to media, media player through to the amplifiers and speakers, then there would be no additional harmonics to the original A4 notes own natural harmonics.
3) Expressing HD in dB makes it easier to visualize the spl relative to the original music signal as per Benchmark's.
So basically, I can see that you don't buy Fourier theorem/series, that allow us to analyze any periodic waveform by breaking it down to the harmonic components, and the the what you called "deformed" waveform is actually a non deformed waveform plus the harmonics (distortions) created by the reproduction devices. It is a well known fact in the EE world but at this point, I don't know what else I can say and link to convince you that the so called "deformed" waveform is 100% equal to the original non deformed waveform + the effects of the harmonics created by the devices in the signal chain of the reproduction system. Fourier has proved it many years ago. Fourier is the foundation of communication system, without it, we can forget about the advance of telecommunication. Now we are borderline on the EE territory so below are just recommended readings if you are interested and have time to spare.
https://en.wikipedia.org/wiki/Fourier_analysis
https://en.wikipedia.org/wiki/Harmonic_analysis
May be we can forget about Fourier, and use a over simplified analogy that I can think of, so consider the following:
15 = 1+2+3+4+5, imagine 1 is the fundamental of that A4 note, 2, 3, 4, 5......(there are many more but let's just stop here) would be the harmonics, but no distortions yet. Next, consider 16.5 = 1+0.1+2+0.2+3+0.3+4+0.4+5+0.5 and now the 1, 2, 3, 4, 5, are the fundamental, 2nd, 3rd, 4th and 5th harmonics of the note A4 and the 0.2, 0.3, 0.4 and 0.5 are the individual harmonic components of the harmonic distortions. Just for simple demo, call those all at 10%, i.e. each of the 2nd, through 5th harmonics are at 10% of the A4 notes fundamental and the 1st, 2nd, through 5th harmonics.
So in this make up example, I simply try to show the difference between the naturally produced harmonics by the musical instrument, piano in your example, and the harmonics produced by the electronic devices, that are considered distortions, hence the term harmonic distortions.
One important point to note, is in the link I included in my previous post but I guess you might have overlooked it so let me repeat it here, the bold and underlined part:
https://en.wikipedia.org/wiki/Pure_...e,hearing thresholds at different frequencies.
"Unlike musical tones that are composed of the sum of a number of harmonically related sinusoidal components, pure tones only contain one such sinusoidal waveform."
Some other definitions from wiki can be useful in our discussion, no advanced EE stuff, just simple wiki definitions:
Again, the important points I want to highlight are bold underlined.
On harmonic distortions:
https://en.wikipedia.org/wiki/Total_harmonic_distortion
To understand a system with an input and an output, such as an audio amplifier, we start with an ideal system where the transfer function is linear and time-invariant. When a sinusoidal signal of frequency ω passes through a non-ideal, non-linear device, additional content is added at multiples nω (harmonics) of the original frequency. THD is a measure of that additional signal content not present in the input signal.
The total harmonic distortion (THD or THDi) is a measurement of the harmonic distortion present in a signal and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. Distortion factor, a closely related term, is sometimes used as a synonym.
On pure tone and music tones:
In psychoacoustics, a pure tone is a sound with a sinusoidal waveform; that is, a sine wave of any frequency, phase, and amplitude.[1] In clinical audiology, pure tones are used for pure tone audiometry to characterize hearing thresholds at different frequencies.
Pure tones have been used by 19th century physicists like Georg Ohm and Hermann von Helmholtz to support theories asserting that the ear functions in a way equivalent to a Fourier frequency analysis.[4][5] In Ohm's acoustic law, later further elaborated by Helmholtz, musical tones are perceived as a set of pure tones. The percept of pitch depends on the frequency of the most prominent tone, and the phases of the individual components is discarded. This theory has often been blamed for creating a confusion between pitch, frequency and pure tones.[6]
Unlike musical tones that are composed of the sum of a number of harmonically related sinusoidal components, pure tones only contain one such sinusoidal waveform.
Traditionally in Western music, a musical tone is a steady periodic sound. A musical tone is characterized by its duration, pitch, intensity (or loudness), and timbre (or quality).[1] The notes used in music can be more complex than musical tones, as they may include aperiodic aspects, such as attack transients, vibrato, and envelope modulation.
On harmonic analysis and Fourier theorem:
https://en.wikipedia.org/wiki/Fourier_series
https://en.wikipedia.org/wiki/Fourier_transform#Applications
https://en.wikipedia.org/wiki/Harmonic_analysis
https://www.sfu.ca/sonic-studio-web...at,coefficients known as Fourier coefficients.
The Fourier theorem states that any periodic waveform can be approximated as closely as desired as the sum of a series of sine waves with frequencies in a harmonic series
One motivation for the Fourier transform comes from the study of Fourier series. In the study of Fourier series, complicated but periodic functions are written as the sum of simple waves mathematically represented by sines and cosines. The Fourier transform is an extension of the Fourier series that results when the period of the represented function is lengthened and allowed to approach infinity.
@lashto , I have collected many articles on the distortion topic, and this morning I tried looking for one that may be good for you to read. Well the first I opened seems like a good one, so linked below, if I find more, then more to come.
http://www.eselab.si/doc/Chapter13_3.pdf
The key point I would love to influence you on is in the 3rd paragraph on the first page. You only have to read the first several pages unless you want to dive deeper. The key point being that the deformed waveform you referred to is just a matter of presentation by us humans, in reality it can be broken into, represented by an infinite series of sine waves, obviously also, as always by us humans, fortunately as we are the smartest living thing.
"By using Fourier series, it can be shown that the output waveform consists of the original input sine wave plus sine waves at integer multiples (harmonics) of the input frequency."
The author is not only an EE, but hold a Ph.D in EE, and appears to have good standing in this field.
http://www.qualisaudio.com/xfrm/richard_cabot/Rich_Cabot_Resume.htm
http://www.eselab.si/doc/Chapter13_3.pdf
The key point I would love to influence you on is in the 3rd paragraph on the first page. You only have to read the first several pages unless you want to dive deeper. The key point being that the deformed waveform you referred to is just a matter of presentation by us humans, in reality it can be broken into, represented by an infinite series of sine waves, obviously also, as always by us humans, fortunately as we are the smartest living thing.
"By using Fourier series, it can be shown that the output waveform consists of the original input sine wave plus sine waves at integer multiples (harmonics) of the input frequency."
The author is not only an EE, but hold a Ph.D in EE, and appears to have good standing in this field.
http://www.qualisaudio.com/xfrm/richard_cabot/Rich_Cabot_Resume.htm
hold your horses a bit, I am not debating the math. Fourier, Ohm and Helmholtz are all good guys and I had enough beers with them in various Hilbert spaces. Helmholtz seems to know his beers best, he's my favorite
My angle is mostly psycho-acoustics. You can math-split that (distorted) test signal into as many H/HD components as you wish and you can math-assign dB levels to the Hs/HDs or the "HD-floor". It's very useful for many EE purposes. But the human ear does not hear any of those math-spliced Hs/HDs as separate and couldn't care less about that calculated "HD floor" level.
You (still) seem to see a difference between "natural" instrument Hs and amp/dac/etc generated HDs. It's the exact same physical phenomenon, uses the exact same math and sounds the exact same way to our ears. It's the exact same duck!
Same as you hear the piano A4 and all its Hs as one single note, you will hear the amp/dac/etc test tone and all its HDs as one tone. At any volume and irrespective of any conceivable form of (noise) floor.
The piano and the Violin sound different because they have different Hs. There are some other factors in that still unknown timbre thing, but the Hs play a big role (some say the biggest by far, some say the biggest by a bit ... it's all WIP, don't expect news anytime soon).
Here's the 1000 words picture: that's why A4 on a piano has a different timbre than the same A4 on a violin.
Exactly as the Piano and Violin will sound different because of different Hs, a tube-amp and the SS-amp will sound different (different timbre) because of the differences in the Hs/HDs spectrum. In the case of the amps, the Hs actually play a bigger role because (most) other timbre factors are not present. The "tube warmth" and that "musical sound" that audiophiles keep debating debated over trillions of useless internet posts is just a simple bunch of even harmonics.
(for the DYI fans @pkane 's has a very nice H generator on this forum, have fun proving all the above with your own ears.)
Both the violin and the tubeamp will sound same as warm, same as tubey and same as violin no matter the volume. Sorry, there is no device or phenomenon in this world that can hide the Hs/HDs. The volume button, the room-noise and that math-calculated HD-floor do not hide any single H.
If the ear was able to separate those Hs and you were able to hide them under some sort of "floor", it'll mean that a tube-amp will not sound tube-warm at low volumes or a violin will not sound same as warm when played lower volume. They don't. That HD-floor theory produces just funky hiccups wherever you apply it.
I have not found a study for this but I'll go even further: not even a brick-wall-like noise floor will hide the Hs/HDs. It's like the noise floor and the Hs are two different things
Correction. There is something in the universe that can hide the Hs from your ears: other Hs.
If the ear was able to separate those Hs and you were able to hide them under some sort of "floor", it'll mean that a tube-amp will not sound tube-warm at low volumes or a violin will not sound same as warm when played lower volume. They don't. That HD-floor theory produces just funky hiccups wherever you apply it.
I have not found a study for this but I'll go even further: not even a brick-wall-like noise floor will hide the Hs/HDs. It's like the noise floor and the Hs are two different things
Correction. There is something in the universe that can hide the Hs from your ears: other Hs.
P.S.
I guess at this point we both said what was to be said. Even the answer to that "money question" is included if one reads carefully. We can agree to disagree or whatever. But I think we should stop distorting the thread, it's at 250% THD now.
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