In reality, we need both 'convenient' and 'more exact' calculations, depending of the 'depth' of our enquiry, and what we want to learn from it.
In a way, to me, that is a fundamental difference between physics and engineering.
Engineers want results, often pretty good approximations. They will use convenient formulas, often simplified from the basic physics, to make a calculation.
Sometimes, they go astray a little, but mostly they work pretty well.
I was always impressed by Oliver Heaviside and his approach to 'practical' engineering problems, always trying to solve what was often considered 'unsolvable' at the time.
He had a goal in his life, and it first came out as solving problems with long distance telegraphy, which was of interest to him, since he worked in the field, early in his 'career'.
His writings in 'The Electrician' and other publications (when they would publish him) took on some of the biggest names (and sometimes, Blowhards) at the time.
He took on Lord Kelvin, for example, with 'The age of the Earth' controversy. Etc.
He was despised and covertly censored by others high in 'station' at the time.
And this should be a lesson for all who think that what they know is all there is to know, because what they 'know' today, may be modified so much as to be more like the 'rogue critic', who 'had' to be suppressed, and is later found to be correct after all. '-)
In a way, to me, that is a fundamental difference between physics and engineering.
Engineers want results, often pretty good approximations. They will use convenient formulas, often simplified from the basic physics, to make a calculation.
Sometimes, they go astray a little, but mostly they work pretty well.
I was always impressed by Oliver Heaviside and his approach to 'practical' engineering problems, always trying to solve what was often considered 'unsolvable' at the time.
He had a goal in his life, and it first came out as solving problems with long distance telegraphy, which was of interest to him, since he worked in the field, early in his 'career'.
His writings in 'The Electrician' and other publications (when they would publish him) took on some of the biggest names (and sometimes, Blowhards) at the time.
He took on Lord Kelvin, for example, with 'The age of the Earth' controversy. Etc.
He was despised and covertly censored by others high in 'station' at the time.
And this should be a lesson for all who think that what they know is all there is to know, because what they 'know' today, may be modified so much as to be more like the 'rogue critic', who 'had' to be suppressed, and is later found to be correct after all. '-)
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This comment is not really appropriate except as a joke maybe? The time/frequency domain transform pair contains no thrown away or hidden variables and is perfectly reversible. They are EXACT representations of the same thing.
How about imaginary numbers, you run all these a+jb terms through ordinary algebra and at the end you just throw away the imaginary part and get the right answer. Must be a sleight of hand there somewhere?
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Then again Ed, in this age of spelling checkers, dyslectia is no excuse for sloppy spelling
That is howl jung get the wrong works.
It was lots of fun in school when reading Shakespeare out loud. The teacher assumed I had a different edition than the others.
I did learn my left from my right in fourth form. (10th Grade.) I knew there was a scar on my left hand and realized I was down to just checking one hand after a while, so I no longer have to look at my hands to tell left from right. Now P's and 5's stopped being a problem a bit before that.
The good news is that no one had heard of dyslexia when I was in school, so they just marked me down for poor penmanship and bad spelling.
I always have to add a column of numbers down first and then again up to see if I get the same answer.
The biggie is reading legal documents. Sometimes what I read in them the first time isn't there upon later reading. This problem has cost me quite a bit.
So it ain't really funny.
ES
I openly challenge the very 'idea' that double blind testing is the ONLY effective way of noting differences in audio listening quality.
Like Heaviside and his loading coils, many good ideas are first found to be 'unscientific' or 'unnatural' for a period, only to have emerged as a GREAT IDEA, that allows for engineering progress.
Like Heaviside and his loading coils, many good ideas are first found to be 'unscientific' or 'unnatural' for a period, only to have emerged as a GREAT IDEA, that allows for engineering progress.
It is never funny –especially on young age-when behaviour or abilities deviate a bit from the “common”.
been a while since you studied physics john?
loading coils work objectively – beneficial results can be measured, heard blind, independent investigators get the same results - didn't depend on their reading of either side's write ups, allegiance to a Guru
in fact the story line suggests Heaviside's loading coils come from the wave propagation equations - not the "million monkey's with solder irons" process that some audiophile subjectivsts seem to be promoting with raising "try it", "you have to listen" above any theory, existing technology, science knowledge base - or at least any theory subject to the scientific method
loading coils work objectively – beneficial results can be measured, heard blind, independent investigators get the same results - didn't depend on their reading of either side's write ups, allegiance to a Guru
in fact the story line suggests Heaviside's loading coils come from the wave propagation equations - not the "million monkey's with solder irons" process that some audiophile subjectivsts seem to be promoting with raising "try it", "you have to listen" above any theory, existing technology, science knowledge base - or at least any theory subject to the scientific method
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Mr Curl
Please, don’t make a parallelism btn loading coils and challenging DBT.
Heaviside went to great lengths in deriving the theoretical grounds of the idea and conducted numerous comparative actual measurements on physical installations to prove his point.
George
This is what my non-dyslectic daughters never do.
They can never know if the result of the addition is correct.
They can only assume it is correct.
Their chance being correct is low, as they use a pocket calculator instead of hand writing the numbers in columns.
George
I don't. FFT and its inverse are merely ways of exactly transforming sampled data from time to frequency domains and back again. Any real difficulties come from implementation problems or inadequate sampling. Perceived difficulties come from problems of understanding by the user.RNMarsh said:
FFT is a mathematical transform. Not to be compared with what actually constitutes the real electromagnetic field.
Yes. He was right, as he had the correct theory of transmission lines. It was the 'practical engineers' who were wrong, because they had insufficient trust in the maths (or insufficient knowledge) to accept a counter-intuitive result: adding inductors would improve the frequency response and reduce dispersion.jcx said:
The interesting thing was that back then people wanted to treat long lines as though they were short. Nowadays people seem to want to treat short lines as though they were long. Both groups fail to understand transmission lines.
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My better audio products have: Been used in serious listening comparisons and found to be better than most.
Heaviside had one heck of a problem convincing people to try loading coils. One would have thought from his previous history as being mathematically 'competent' and his numerous previous articles, that it would have been easy, but it was not so.
You would think that after all the designs that I have made in the last 45 years that have achieved awards for sound quality, that I will have an easier time, here, but it is not to be so. '-)
Heaviside had one heck of a problem convincing people to try loading coils. One would have thought from his previous history as being mathematically 'competent' and his numerous previous articles, that it would have been easy, but it was not so.
You would think that after all the designs that I have made in the last 45 years that have achieved awards for sound quality, that I will have an easier time, here, but it is not to be so. '-)
Any tool will get you into trouble if you don't know how to use it (my wife and a pair of pliers?). FFT, like a swept analyzer, can show a lot of data and both can lie with the best of them. Learn how to use the tools and their limitations. Don't dismiss them if you don't get what you expect, figure out why.
Double Blind testing is very powerful but a lot of work and needs real statistical understanding to get useful results. And again be sure you know what you are testing for. John Atkinson admitted he beat a test because he could hear a teltale click in one option. Does that mean the test is invalid or that its a test of sensitivity of the influence of a telltale click? I suspect the visual component of perception is more important to decoding audio stimuli than we give credit for. I think more real research into understanding the relationships is necessary before drawing useful conclusions from audio only testing.
In a movie theater, dialog is rarely stereo but every viewer can place the sound with the moving lips (even when out of sync). Does this mean that stereo doesn't matter or that you need visuals to decode stereo?
Double Blind testing is very powerful but a lot of work and needs real statistical understanding to get useful results. And again be sure you know what you are testing for. John Atkinson admitted he beat a test because he could hear a teltale click in one option. Does that mean the test is invalid or that its a test of sensitivity of the influence of a telltale click? I suspect the visual component of perception is more important to decoding audio stimuli than we give credit for. I think more real research into understanding the relationships is necessary before drawing useful conclusions from audio only testing.
In a movie theater, dialog is rarely stereo but every viewer can place the sound with the moving lips (even when out of sync). Does this mean that stereo doesn't matter or that you need visuals to decode stereo?
Some people trust their ears. You have the need to peek. Your privilege, of course, but even the smallest understanding of how human perception will inform one of why these sorts of controls are necessary IF you want to actually know what you (or someone else) could hear.
SY, this is MY reality. I would rather go with what other people think of my efforts, primarily, and secondarily, what I have found 'wanting' in my previous efforts over the last 45 years, that became 'obvious' enough that I was forced to move away from that specific design, because of the 'problems' that became apparent to me, only after YEARS of listening to the product, and I wanted better.
Sy,
One of life's lessons I learned earlier on was that you have to look at parity of price in the audiophile world. I brought a very well designed product to the CES and Stereophile shows and was admonished for setting my selling price to low. This was an eye opener to me. I thought that I had priced the product well to sell based on cost and profit margins but the product was just to good to sell at my price point. I was upsetting the apple cart so to say, the speaker sounded much better than many that had prices 10 times the price and dealers did not want the product in their stores, it would have gutted their higher end product sales. Also it is a matter of perception. If you made and many have a product better than say an Apple product and attempted to sell it at a lower price point people seem to feel that the product must be inferior if the price is lower.
A friend once told me that his first job was to sell ball point pens. He packaged the pens in two ways, as a low cost pen and at a much higher cost in a different package. The cheaper model that was identical to the expensive model languished on the shelf and the expensive pens sold well. Perception is a large driver of consumer choice, I will not make that mistake again.
One of life's lessons I learned earlier on was that you have to look at parity of price in the audiophile world. I brought a very well designed product to the CES and Stereophile shows and was admonished for setting my selling price to low. This was an eye opener to me. I thought that I had priced the product well to sell based on cost and profit margins but the product was just to good to sell at my price point. I was upsetting the apple cart so to say, the speaker sounded much better than many that had prices 10 times the price and dealers did not want the product in their stores, it would have gutted their higher end product sales. Also it is a matter of perception. If you made and many have a product better than say an Apple product and attempted to sell it at a lower price point people seem to feel that the product must be inferior if the price is lower.
A friend once told me that his first job was to sell ball point pens. He packaged the pens in two ways, as a low cost pen and at a much higher cost in a different package. The cheaper model that was identical to the expensive model languished on the shelf and the expensive pens sold well. Perception is a large driver of consumer choice, I will not make that mistake again.
Dick showed a complete understanding of the mathematical underpinings of the FFT. Nothing he said would bother me, so what are YOU trying to say?
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