hum....
both Mr Geiger and Mr Geddes seem to be approaching the discussion of distortion in loudspeakers as something that can't be discussed without the prerequisite education.
Geddes professes that like him JBL does not consider distortion important.
Geiger, i take it from his profile here at DIY Audio, would also be an industry insider.
draw your on conclusion folks!
both Mr Geiger and Mr Geddes seem to be approaching the discussion of distortion in loudspeakers as something that can't be discussed without the prerequisite education.
Geddes professes that like him JBL does not consider distortion important.
Geiger, i take it from his profile here at DIY Audio, would also be an industry insider.
draw your on conclusion folks!
For those wishing to understand more, a repetitive waveform can be broken down, or expanded, into a sum of other frequencies. They would consist of a fundamental frequency and it's harmonics. It's undergraduate math like this: https://www.google.com/url?sa=t&rct....CHP04.1.pdf&usg=AOvVaw3wP2ZJq29Xvuitb2o5G0o6
If the harmonic frequencies are even, i.e., 2,4 6,8, etc., they are referred to as even order. The odd number harmonics are odd order.
If a higher order even harmonic (not 2nd, but, say, maybe 6th harmonic -- a relatively big-ish even number) exists, then Geddes is saying that lower number even harmonics would also exist and are related (they couple, they are not independent). Also, DC is considered even order, and is a DC offset. In addition, the fundamental may be referred to as the 1st.
These are all things someone with a degree should have learned, or mostly learned, at some point in school, although they may be forgotten after a time if never used.
Talking the way in the way quoted above is just professional engineering language that should have very specific meaning to engineers. There is nothing wrong with it and it serves its purpose well if understood. Those that would like to learn more about engineering can do it or not, great if they do, but it can be a big undertaking if a lot has been skipped along the way.
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Sure, imagine a sin wave that is very heavily clipped on top but not at all on the bottom.
In a speaker, the physical meaning might be that the mechanical center or resting point of the cone is not at the center of its motion limits, or magnetic linearity, or something like that not symmetrical about the resting position. So, if the cone can move only a little way in one direction before becoming nonlinear, but can move farther in the other direction okay, then when you get it moving far enough to hit nonlinear-in-one-direction, there is a DC offset so long as that condition continues.
OK, I can see that, I think the terminology, DC offset, threw me. He's saying only the even order distortions would accumulate to cause that? I presume then, the odd orders would cancel either side of the potential off-set....I'm trying to picture this. Ah, no, the node would be there
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Can someone please explain this. It was previously brought up here. This article seems to indicate that when a source is within two wavelengths or less of a given frequency the sound doesn't disperse as expected, but bounces around.
Sound Fields: Free versus Diffuse Field, Near versus Far Field
This is strange. Since it implies that even without walls the sound is different as one gets closer. I think this may have some bearing on "dynamics"
Perhaps sources from a distance have less environmental distortion but more inherent physical distortion from having to play louder. This would explain the "live sound" better.
Sound Fields: Free versus Diffuse Field, Near versus Far Field
This is strange. Since it implies that even without walls the sound is different as one gets closer. I think this may have some bearing on "dynamics"
Perhaps sources from a distance have less environmental distortion but more inherent physical distortion from having to play louder. This would explain the "live sound" better.
I think each have different views, but we all have to make our own judgment in application. That is the responsible attitude.
Thanks ...
... for the contribution (sans argumentum ad hominem).
I find this article by Dr. Mostafa S. Habib to be a concise and well written treatise of the prerequisite math. As he points out in paragraph 4.3, this regime may be applied to non-periodic (transient) waveforms as well.
Regards,
WHG
... for the contribution (sans argumentum ad hominem).
I find this article by Dr. Mostafa S. Habib to be a concise and well written treatise of the prerequisite math. As he points out in paragraph 4.3, this regime may be applied to non-periodic (transient) waveforms as well.
Regards,
WHG
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Probably not an explanation for "live sound" better, whatever that means exactly. If you think about it all electric instruments use speakers, so the same effects must apply to them. And then acoustic instruments are in part transducers themselves, and sound waves emitted from them would be expected to be subject to the same kinds of effects.
Also, basically it seems like we are talking about complex situations involving mechanical vibration, wave mechanics, and maybe fluid dynamics. So, the exact details would probably be very dependent on the particular situation.
However, with most things like this there is not an exact line at two wavelengths away, or whatever distance, where an abrupt switch from one thing to another occurs. Rather someone has tried to create a classification system for when effects have changed enough with distance that it makes sense to approximate them using a different model, that's all.
No argumentum ad hominem was intended. No attack on anyone in any way. Just trying to state the facts. For people who would like to learn engineering, one doesn't have to go to graduate school to learn a lot of the most useful stuff.
Also, it is a fact of life that people tend to forget math they don't use. I know more that one senior PhD physicist who every once in a while wishes they still remembered everything they learned back in postgraduate classical eletrodynamics. If wasn't something they used after they got of school, some of it gets lost.
The majority of audio power amplifiers are feedback devices and therefore they have far
lower distortion than speakers that most often do not employ feedback.
Earl, I want to be nice but I see you post absurd claims fairly often so it is difficult.
Have you published this secret test that is so superior to everyone else's?
Why not, if not?
What was the amp that you tested?
It must have been pretty bad to have failed so miserably.
Amp designers have known for years that the usual THD and IMD tests if low enough in
level are inaudible. They also know that jump discontinuities such as crossover distortion
are nasty (perceptually irritable) and far more audible. We have lived with this knowledge
for many decades and yet you act as if you need to educate all of us - it is rather amusing
because you are showing your ignorance of what we already know.
Hafler did a null test years ago with their XL line of amplifiers that will uncover all forms of
distortion, are you familiar with that?
I've done level matched A/B tests of several excellent power amps and it is as if the
switch is not connected.
I doubt it about JBL, why would they bother to produce lower distortion drivers if it does not matter? Where is the return on investment for their engineering?
Thanks Again ...
... it was a refreshing read.
The Latin applies elsewhere in this thread.
Regards,
WHG
... it was a refreshing read.
The Latin applies elsewhere in this thread.
Regards,
WHG
That's sort of what I was getting at, there isn't an exact point where the behavior changes. But the bottom line is that according to the link I posted soundwaves emitting from a source behave different depending on distance from a source.
This is of course important since it means that there might be mechanisms in our hearing that can tell the scale or size of a sound source.
Of course our eyes can tell large objects from small, based simply on the behavior of light, and its why sitting closer to a small TV isn't the same asa big screen.
Speakers are hardly linear the point that has been made is that the distortion resulting from
their non-linearity is perceptually not an issue (or however Earl says this). I do not agree
with the point but that is Earl's claim.
Yes, human hearing is also non-linear.