is it possible to clearly define linear and non-linear distortion so these terms aren't semi ambiguous.
distortion (to my understanding) is "any" anomaly that is not part of the original signal.
so regardless of what classification you give it harmonic,linear,non-linear it's still distortion.
the mechanism of distortion needs to be identified (this maybe an oversimplification) but if an amplifier distorts can we blame the driver? and conversely if we hear distortion from a driver are we to conclude that "it" is the source?
from my standpoint both are possible and can't be viewed as mutually exclusive.(neither works well on there own)
distortion (to my understanding) is "any" anomaly that is not part of the original signal.
so regardless of what classification you give it harmonic,linear,non-linear it's still distortion.
the mechanism of distortion needs to be identified (this maybe an oversimplification) but if an amplifier distorts can we blame the driver? and conversely if we hear distortion from a driver are we to conclude that "it" is the source?
from my standpoint both are possible and can't be viewed as mutually exclusive.(neither works well on there own)
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Linear distortion = alteration to spectrum or waveform/time domain.
Nonlinear distortion = any alteration to the signal that results in new spectral components.
Nonlinear distortion = any alteration to the signal that results in new spectral components.
Well, don't think I ever said it was inaudible 🙂
Nope, I make sure I hardly ever end up in a situation where I push the drivers to hard. LND IS a factor of course, all I'm saying is that it is one of the easiest to design away from being a major concern. Of course concert levels from 20-20k with bookshelf speakers is impossible without excessive distortion but that was not the original question here.
/Anders
after an extended listening session of the sound files Weltersys created all i can say is that the clips employing tones made it easier to distinguish harmonic content (sonic signature if that term makes sense) i am wondering what differences i would perceive if the playback (and recording) chain where removed from the equation.
to say that there was a level of distortion i found objectionable can't say as i think playback medium, normalization and applied eq all narrowed my ability to make that distinction/judgment.
to say that there was a level of distortion i found objectionable can't say as i think playback medium, normalization and applied eq all narrowed my ability to make that distinction/judgment.
Earl mentioned the audibility of non linear distortions in electronics a opposed to speakers with higher levels of static distortions.
This makes made think back top long ago courses about the how solid state devices work, ie the structure of the silicon in various transistors. The physics of the BJT junction is pretty complex compared with the physics of a vacuum tube. Not to open that can of worms.
Earl's posts always contain a lot to think about.
This makes made think back top long ago courses about the how solid state devices work, ie the structure of the silicon in various transistors. The physics of the BJT junction is pretty complex compared with the physics of a vacuum tube. Not to open that can of worms.
Earl's posts always contain a lot to think about.
Someone else did and you backed it up. 🙂
It's also one of he most expensive things to design away from. It's good that you hardly ever end up in situations where distortion is a problem, I know for a fact that there are bunches and bunches of people who do, also sometimes without knowing it untill they experience something cleaner with higher performance.
Then of course "major concern" and its definition is maybe a discussion on its own. 🙂
Thanks Anders, I completely agree with you.
"like the Devil reads the Bible " - I like that phrase!!
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One cannot expect to use a loudspeaker beyond its intended application and not have it sound bad. If your position is that one can always play a speaker loud enough that it has audible NLD then yes, that's true, but that is a completely absurd position.
My position is that I can always design a speaker such that it has no audible NLD at intended listening levels. In my room that's about 110 - 120 dB - easily enough headroom for any playback level that I am likely to reach.
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Turk - it is possible to do, but perhaps not simply. As I said early on what I came away with after studying nonlinear systems intently was how very difficult they were to understand. This is ground ripe for misunderstanding and low comprehension of the issues.
Basically the root definition of Linear versus non-linear are mathematical. In this domain the issues are unambiguous, but in the audio and subjective domain they are anything but. It is true that any modification of the waveform is "distortion", but there are two distinctly different types of distortion - linear and non-linear. Linear distortion has the same effect on the signal no matter how high or low in level the signal gets. Nonlinear distortion has different effects at different levels and different effects for different signals - like THD and IMD, which both result from a nonlinear system but create different outcomes.
Linear systems cannot introduce new tones that were not there originally, NLD can. This is a major distinction. One thing that makes this whole thing complex as far as audibility goes is that the ear itself is highly nonlinear! This means that its nonlinearity can mask much of the nonlinearity in the system - but how much and where? That's the real question.
Basically if you want to understand nonlinearity you have to dive into the mathematics to really get good solid definitions that are free from ambiguous interpretation.
How about subharmonic NLD, usually in tweeters, do you also find it inaudible?
Attachments
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A paper on subharmonic distortion in compression drivers:
www.beyma.com/uploads/descargas/1352741021.pdf
www.beyma.com/uploads/descargas/1352741021.pdf
Sub harmonics is an interesting issue. That's because they cannot be generated by any process that is time-invariant (See Schetzen for a proof of this. Surprised me as well!) There is no mathematical mechanism for this. What can cause it is a nonlinear system that is time variant such as would occur from thermal modulation effects, especially in tweeters with small voice coils. Since no time-invariant system can generate sub harmonics there were no sub-harmonics present in any of the systems that we looked at in our study of THD perception. There could have been in the compression driver study, but to what level I do not know.
The Beyma paper clearly shows (Eq. 1) that the system needs to be time-variant for sub-harmonics to occur.
It is, to me, a fascinating aspect that needs more study as this is a fundamental indication for thermal nonlinear effects. Audibility has never been investigated to my knowledge.
The Beyma paper clearly shows (Eq. 1) that the system needs to be time-variant for sub-harmonics to occur.
It is, to me, a fascinating aspect that needs more study as this is a fundamental indication for thermal nonlinear effects. Audibility has never been investigated to my knowledge.
That is a fascinating plot with multiple 1/2 orders. I suspect strong thermal modulation going on there. What kind of tweeter is that? I'd like to do those tests myself.
There are "oil-canning" diaphragm effects that can do this, but that takes an especially weak cone to do.
By the way - Prague is my favorite city in the EU. A beautiful historic city.
Thinking about the sub-harmonic issue, this is well worth studying. I can see how it could change a lot of things. It is a wide open field as far as I can tell. The Beyma paper didn't get much traction, but I am not sure that means anything.
Turk,
If the recording and playback were removed, that is you heard what the mic heard through the original playback system, the only way to listen at consistent levels would be to ascend twice as far in the sky for each 6 dB increase in drive level. However, high frequency air absorption would then progressively attenuate the HF, making the harmonic distortion harder to hear at greater distances.
Our hearing is sensitive to frequency response differences, without equalizing the response of the drivers all flat, there would have been obvious differences in response that would swamp any subtle differences between the driver's sonic signature.
From what you wrote above, it appears you can't make much distinction between the drivers when using the music source.
As Earl said in post #34:
"One thing that makes this whole thing complex as far as audibility goes is that the ear itself is highly nonlinear! This means that its nonlinearity can mask much of the nonlinearity in the system - but how much and where?"
One of the most surprising things is that what sounded horrific to my ears during the actual playback was far less objectionable in the recording listening back over headphones at a moderate level. This did not change bouncing down from the high resolution 44.1kHz 16 bit recording to the MP3 format. My "ear distortion" adds to the driver distortion, the combination of high SPL and high distortion sound worse than high distortion at low level.
The addition of the LF portion of the music audio to the HF horn masked the distortion further. In this thread recordings of the HF with no "virtual LF driver" are available:
http://soundforums.net/varsity/4329-...html#post29143
It is easier to detect the differences in the HF driver's different sound at various drive levels when heard without LF content.
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