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Old 30th August 2012, 04:32 AM   #101
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Yes, as Floyd Toole is said to have remarked, "The greatest fallacy in audio is that what offends the eye offends the ear in like measure".
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Old 30th August 2012, 04:45 AM   #102
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The eye pays little attention to the time domain, which makes it possible to use time-redundancy to lossy-compress video (portions of video frames with no motion in them are discarded with little to no apparent loss). We're not going to notice that the grain structure of the sky isn't changing; visually, it might even be an improvement.

For the ear, time-delayed reflections are translated into distance and space, a very different system than the eye uses to estimate distance. The ear hears into things, while the eye looks at surfaces.
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Old 30th August 2012, 06:16 AM   #103
graaf is offline graaf  Poland
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Quote:
Originally Posted by FrankWW View Post
Quote:
Pedant alert- the time/frequency trade-off is not the Heisenberg relationship. It's a classical uncertainty, well-known a hundred years earlier. It is, though, an effective way of illustrating the general concept.
exactly, it is just rethoric, use of analogy for illustrative puropses
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Old 30th August 2012, 07:00 AM   #104
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Originally Posted by Lynn Olson View Post
I agree in principle, but we have to be aware the visual system can mislead us. Case in point: square waves from a linear-phase speaker look much better on an oscilloscope than the square waves from a speaker using an allpass crossover. The allpass function makes a complete mess out of the square wave.

However ... where the scope does not match hearing is display of nonlinear distortion. As a former Tektronix employee, we were aware that visually seeing sinewave distortion on a scope is very, very difficult. For trained observers (we're talking Tek here), 3% is about the limit, and that takes really good eyes. But 3% distortion for audio is quite bad, and clearly audible, particularly if high-order harmonics are present. Fifth-order (and higher) harmonics sound pretty bad, yet are invisible on a scope. (Scope electronics can have up to 1% nonlinear distortion, since greater linearity cannot be seen on the display.)

If we switch domains to a spectrum analyzer, then the analyzer discards time information, displaying only log-scale amplitude in the frequency domain. So a loudspeaker with very poor impulse could still look good on the spectrum analyzer.

So now we're in the soup of trying to match visual displays to audio perception. In visual terms, linear allpass distortion looks far worse than 10% nonlinear distortion, which is fairly subtle visually. But I think most of us here would agree that 10% distortion is completely unacceptable for quality reproduction, while there might be debate about audibility of linear allpass distortion.
This leads to a fairly simple conclusion:
You can not use one single measurement to determine the quality of a speaker.
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Old 30th August 2012, 08:09 AM   #105
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Quote:
Originally Posted by Dirk95100 View Post
This leads to a fairly simple conclusion:
You can not use one single measurement to determine the quality of a speaker.
I can think of about ten parameters that are important for loudspeakers. Part of the reason loudspeakers are difficult to design is the requirement to cover nearly three decades; a three-decade bandwidth is difficult enough for an RF antenna without bandswitching, much less a transducer that also has to have reasonably low distortion.

OK, now we're agreed on the need for a constellation of parameters, how should they be weighted? Now we're back in the subjectivist soup again, since different listeners may well have different perceptions, and almost certainly will have different musical tastes.
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Old 30th August 2012, 08:46 AM   #106
soongsc is offline soongsc  Taiwan
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Just looking at levels, I would say getting CSD values 40db below original level as fast as possible would be of very high priority. Near field driver harmonic levels would also be very high priority. The higher level one has the higher priority to get fixed.
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Old 30th August 2012, 10:06 AM   #107
graaf is offline graaf  Poland
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Originally Posted by Tom Danley View Post
If a perfect measurement microphone exactly captures the acoustic pressure of one single point in space and converts it into a Voltage signal, why wouldn’t the ideal speaker be at least a close reciprocal of that?

How can science (the vast array of measurement tools available now) be used to understand where and why it falls short?
I think I can agree that an ideal monaural loudspeaker should be as close reciprocal of a perfect microphone as possible

but it is not enough - because what kind of a microphone and what kind of a speaker? omni? dipole? cardioid? ?

furthermore - in stereo/multichannel - what kind of microphone array and what kind of an equivalent loudspeaker array?

moreover - where is the listener in all of it? what exactly are we trying to get for him? are we trying to put the listener as if in the original soundfield in place of the microphone array as in case of dummy head recordings for headphone binaural? or what are we trying to do?

in case of conventional loudspeaker stereo triangle it seems that we simply do not know at all what we are doing - it is just using some old tricks that happen to work somehow creating some kind of picture - somewhat more or less realistic for some, not so for others

there is no science behind this technology - it is just hit-and-miss, a chimpanzee technology

Last edited by graaf; 30th August 2012 at 10:12 AM.
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Old 30th August 2012, 11:51 AM   #108
MaVo is offline MaVo  Germany
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"putting the science back into speakers" is a meaningless phrase if applied this broad. i am sure professionals like tom go at their business with quite a scientific approach, so in this case nothing needs to be put back. in other cases, it boils down to the individual taste. i figured out what i like in audio in a quite long process of build/discard and could not be be less interested if science told me what i like isnt the right thing. and companies that make money with consumer stuff, they would probably only bother if the science increased their money spend per money earned ratio. in the end, science is allready where it needs to be.
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Old 30th August 2012, 01:44 PM   #109
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A thing that I find is that my reactions to music are almost entirely visceral and emotional, the intellect has very little to do with it, and that's why I like it.

I suspect it is because of this that a lot people think that there must be some sort of ghost in the recording and reproduction equipment, when as a scientist all that I can say is that we have never found one and that it is the performance and the composition etc.where the ghost lies, and not in the machines.

There is of course a huge industry that has sprung up by taking advantage of this belief and many pundits willing to pay lip service to it.

In fact it has grown so large that some people now contend that it must be true because so many people seem to believe it.

A great many people also believe that the earth is flat and six thousand years old, so does this mean that it is in the places where this is the consensus?

The commercial imperative is what drives the audio industry and when you have such a situation a science does dominate, and that is marketing psychology.

The guru of the market psychologists is B.F. Skinner the inventor of behaviorism.
He said that since we are all being conditioned all the time anyway it was incumbent upon the powers that be to see that we were conditioned in the right way, and foe him the right way is consumer capitalism, and the marketers concur. Marketers use this as their rational, and have spent vast amounts of money in research into the subject, and it does work, it is also true that most people think that it doesn't work on them.

The audio industry only wants this particular science in loudspeakers because they sell more of them that way, Bose for instance employs hoards of science Phd' s and there consumer outlets are a tour de force in marketing psychology, they use the physical sciences to design the cheapest ones that give the most profit margin, and then psychology to sell them, and they are only one of the more glaring examples.

I would suggest that this is a bit of science that needs to be taken out and not put in, but as we all know there is fat chance of that.

Anyway I now climb down from my soap box and await comments with baited breath.
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Old 30th August 2012, 02:02 PM   #110
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If we know how to create the illusion of the real event, then we can go from there.
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