Brett said:
I would not rule that out before a controlled blind test.
Experienced testers use to go for 0.01%THD as a rough limit for audible distortion. Of course it depends on spectrum and also program material.
/Peter
I think it was Hiraga who first proposed the most "natural"
distortion pattern is one of decreasing level with increasing
order. The delta between one harmonic and its
immediate predecessor had to be somewhere between
10-25db.
As I recall the reason for this pattern was that the brain had to
make the same adjustment for naturally occurring ear
non-linearities.
Any device (amplifier) that could emulate this pattern would be
perceived by a listener as sounding "neutral" because the
ear/brain could not distinguish this pattern from its own internal processing.
Similiar to how the eye has a blind spot that is filled in and we don't even perceive it.
So their may actually be two ways to make a natural sounding
system. 1) Emulate this pattern, or 2) Eliminate distortion all
together.
Tube amps seem to have success because they try and do 1).
The hard part about 1) is that the delta between a harmonic
and its immediate predecessor may depend on level and
harmonic order.
So it might be easier to go for 2).
I think the ear might have an incredible sensitivity and that
is why we haven't had full success yet with either approach.
It also needs to be done at a system level, not just at the
amplifier.
distortion pattern is one of decreasing level with increasing
order. The delta between one harmonic and its
immediate predecessor had to be somewhere between
10-25db.
As I recall the reason for this pattern was that the brain had to
make the same adjustment for naturally occurring ear
non-linearities.
Any device (amplifier) that could emulate this pattern would be
perceived by a listener as sounding "neutral" because the
ear/brain could not distinguish this pattern from its own internal processing.
Similiar to how the eye has a blind spot that is filled in and we don't even perceive it.
So their may actually be two ways to make a natural sounding
system. 1) Emulate this pattern, or 2) Eliminate distortion all
together.
Tube amps seem to have success because they try and do 1).
The hard part about 1) is that the delta between a harmonic
and its immediate predecessor may depend on level and
harmonic order.
So it might be easier to go for 2).
I think the ear might have an incredible sensitivity and that
is why we haven't had full success yet with either approach.
It also needs to be done at a system level, not just at the
amplifier.
I know one amp (or a couple) that has been tested as transparent where all other amps failed.
So I say that 2 is definately possible.
/Peter
So I say that 2 is definately possible.
/Peter
Links to said tests please.Pan said:
I believe the numbers given are way too optimistic. Geddes tests found higher and I've seen a few people with excellent ears not even come close to that using the Klippel test.
I light of no proof, I shall view them as unfounded assertions based upon my own experience.
Brett said:
I said that I, based on my own blind tests, would not rule out what you said before I had performed a blind test on gain stages with those numbers under discussion.
I also said that experienced testers (those that I know and those that I have talked to) use to go for 0.01%THD as a rough limit.
Don't know what there is to proove.
/Peter
crossover distortion can be made as low as 0.01% and yet it is still heard.
I think the reason it is audible is that the 2H & 3H are almost absent and the vast majority of the distortion is due to the higher harmonics many of which are not continuous but very spiky in nature.
We seem to be very good at isolating these spiky artifacts and "hearing" them.
I think the reason it is audible is that the 2H & 3H are almost absent and the vast majority of the distortion is due to the higher harmonics many of which are not continuous but very spiky in nature.
We seem to be very good at isolating these spiky artifacts and "hearing" them.
What we need is a "human ear.model" for our simulators.🙂
How can distortion of that order be heard?? Most speakers
and even the best headphones can barely do .1% so
the amps distortion would be drowning in a sea of speaker induced distortion..
An externally hosted image should be here but it was not working when we last tested it.
OS
ostripper said:
Well Our hearing has a dynamic range of 120-130dB and masking only take place effectively for tones above and close to the fundamental.
Play around with some software and find out for yourself. 🙂
First, the best speakers and headphones has about 0.01%THD at 80-90dB SPL but sure, many products are poor designs technically speaking.
Second, the notion that distortion in one stage would totally and atuomatically mask distortion from another is based on.. assumptions and it is wrong. 🙂
Look at it this way, an instrument has "distortion" at 10-50% or so.. yes, the harmonic overtones is often a big part of the total power of an instrument. Does this mean that this cover up 1-5%THD in the amp or another link in the chain? Of course not!
/Peter
Why not show this graph insted?
An externally hosted image should be here but it was not working when we last tested it.
To Pan
By the way, the fact that the cochlea is full of water has nothing to do with its ability to ring a certain way! A sound wave can be generated in water! Just the damping factor (again a damping factor) of the ringing system will be different and the ringing frequencies different (difference of speed in the different mediums). Any medium that can have a pressure can carry sound!!!
Anyway, this is the explaination of ear physiology encountered in many articles so I am not bringing some breakcking news here!
The non-linearity for pitch and level is poorly understood, some say it could be purely a neuronal effect and nothing mechanical in the cochlea.
Another fascinating thing is that if you produce a tone and all its harmonics and remove the fundamental and let ear it by a human, the fundamental will be heard even if it's not there! It's a part mechanical, part brain processing phenomenon.
Pretty amazing...
Ragards
By the way, the fact that the cochlea is full of water has nothing to do with its ability to ring a certain way! A sound wave can be generated in water! Just the damping factor (again a damping factor) of the ringing system will be different and the ringing frequencies different (difference of speed in the different mediums). Any medium that can have a pressure can carry sound!!!
Anyway, this is the explaination of ear physiology encountered in many articles so I am not bringing some breakcking news here!
The non-linearity for pitch and level is poorly understood, some say it could be purely a neuronal effect and nothing mechanical in the cochlea.
Another fascinating thing is that if you produce a tone and all its harmonics and remove the fundamental and let ear it by a human, the fundamental will be heard even if it's not there! It's a part mechanical, part brain processing phenomenon.
Pretty amazing...
Ragards
This is the range from quietest to loudest. Add a noise at -40 db to pop music at zero and theres a good chance you wont hear it. Distiortion is never heard alone its ontop of the source.
you need a better definition of distortion, an acoustic instrument is not distorted. Is adding EQ distortion? Is adding reverb distortion? As soon as the sound goes thru a microphone it is "distorted"!
yes, distortion is everywhere. thunderclap occurs, reverberates off of mountains, muffled by trees-vegetation, finally reaches
dirty earwax filled ears, interpreted by brain with hangover
... 4 distortions already...😀
OS
dirty earwax filled ears, interpreted by brain with hangover
... 4 distortions already...😀
OS
darian said:
I did not say anything about that. What I said was that water is not compressible (to any significant degree that is) and I see no reason why the tappered pipe (as you said) would be cause of nonlinearities.
Of course! I think anyone over 5 years of age or so have noticed that one can hear sound under water, even I. ;-)
Make that any medium, period.
Amazing indeed!
/Peter
Hello,
If you want to know more about physiology of the ear, I attached a very interesting file.
To Pan,
A soundwave exciting a pipe generates standing waves that are harmonics of the fundamental. So these harmonics are non linearities.
http://www.phys.unsw.edu.au/jw/pipes.html
Technically a certain pipes sould have a certain resonance frequency where the response is maximal, then on each side of it the response falls according to the Q factor of the system. That is why the Fletcher -Munson curve has grossly a upside-down bell shape. Of course the cochlea is not a perfect tapred pipes and is not straight but a spiral. So the response is much more complex and it has the great advantage of tremendously broadening the response of the sytem by making it utterly complex. It also generates a lot of harmonics that are even different in nature for differet frequencies. Very very complex...
Regards
If you want to know more about physiology of the ear, I attached a very interesting file.
To Pan,
A soundwave exciting a pipe generates standing waves that are harmonics of the fundamental. So these harmonics are non linearities.
http://www.phys.unsw.edu.au/jw/pipes.html
Technically a certain pipes sould have a certain resonance frequency where the response is maximal, then on each side of it the response falls according to the Q factor of the system. That is why the Fletcher -Munson curve has grossly a upside-down bell shape. Of course the cochlea is not a perfect tapred pipes and is not straight but a spiral. So the response is much more complex and it has the great advantage of tremendously broadening the response of the sytem by making it utterly complex. It also generates a lot of harmonics that are even different in nature for differet frequencies. Very very complex...
Regards
cbdb said:
Of course, that 's the definitin of the term dynamic range.
I don't know what that has to do with the audibility of HD and IMD but can you please explain what you mean by "-40dB to pop music at zero"?
Please also be open to the possibility that people listen to other types of music than overcompressed and overlimited pop.
What do you mean by alone and ontop of the source?
What!?
But please make some effort to understand what's written. I wrote "distortion" in an attempt to explain that the harmonics of an instrument are similar to HD. I started that text with these words "Look at it this way.." also a clear indication that I tried to present a way of thinking of this so Ostripper would understand that what he brought up is not correct.
Frequency and phase deviations is called linear distortion.
But of course you must think in a wider perspective. Think about RIAA correction and reedbook pre-emphasis for example or why not a pole shifting filter to extend the frequency response of a woofer for a more linear response and better groupdelay.
Used as above I don't think anyone would call EQ distortion but rather correction of a present distortion.
Reverb is technically speaking linear distortion since phase and frequency response is manipulated, not that I would want to be without it though. 🙂
Absolutely. However the best microphones have verey good performance regarding both nonlinear distortion and linear distortion. The biggest problems with mic's is noise and polar pattern. Next to speakers mic's can be considered the weakest link in a recording and playback chain.
/Peter
darian said:
Thanks for the PDF, I'll read it soon.
But a pipe filled with air and a pipe filled with water has major different charactereistics. Air is extremly compressable and that makes it nonlinear. I play flute (and have made a couple myself as well) and obviously by listening to it you hear that there is something more than the fundamental going on and I also record flute and look at waveform and doing frequency analysis of instruments. I recorded the lowest note of a Low D the other week and the waveform was almost a pure slightly smoothed triangular wave, indicating dominantly odd order harmonics added to the fundamental note.
edit: now that I think about it I'm not sure how much 2nd and 3rd there was. Perhaps I'll do an analysis tomorrow.
Darian, funny about that website about windinstruments at the flute section there's a picture of a wooden flute made by Terry McGee, I bought a flute from him some years ago. 🙂
/Peter
And what I brought up with the flute above brings us right back on topic. The note I analysed contained plenty of 3rd order harmonic but still sounded very warm and smooth. And that makes me wonder.. is it really so that we should focus on pressing down the 3rd order and allowing more 2nd order?
To my ears it sounds better to lower the distortion and make it more symmetrical (dominantly odd order harmonics). This also results in lower IMD levels.
/Peter
To my ears it sounds better to lower the distortion and make it more symmetrical (dominantly odd order harmonics). This also results in lower IMD levels.
/Peter
Well, okay the air is less linear so in a flute where the pressure variations can be tremendous you can have distortion by the air medium itself. In everyday life before a sound coming from loudspeaker to your ear suffers noticably from air distortion, you will have to use a lot of power! Actually, the ear will probably distort way before! Well, the distortion I was talking about was not coming from the liquid in the cochlea but from the physic of the cochlea itself.
So you know physics of pipes as I see. So as being a closed pipe, the cochlea has all the harmonics generated, even and odd, so these are mechanical non linearities that the hair-cells will perceive. So you can agree with me after all that the cochlea is by essence non-linear and induces distortion...
The distribution of harmonics is following a certain pattern so if you respect it it should be almost non-perceptible like Hiraga said. High order harmonics are not generated in high amount by the cochlea so the brain cannot correct them and they sound unatural, so artificial sounding and aggressive.
Regards
So you know physics of pipes as I see. So as being a closed pipe, the cochlea has all the harmonics generated, even and odd, so these are mechanical non linearities that the hair-cells will perceive. So you can agree with me after all that the cochlea is by essence non-linear and induces distortion...
The distribution of harmonics is following a certain pattern so if you respect it it should be almost non-perceptible like Hiraga said. High order harmonics are not generated in high amount by the cochlea so the brain cannot correct them and they sound unatural, so artificial sounding and aggressive.
Regards
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