Yes Stocker, my mistake.... please, forget that.
Cheers for the wine we will have together.
All rigth.
Peace for us brother..i misunderstood.
Carlos
Cheers for the wine we will have together.
All rigth.
Peace for us brother..i misunderstood.
Carlos
Years & years ago i decided that single number THD is an irrelevant measurment.
Earl Geddes has done some recent research which estalishes that using proper scientific method. He has also come out with a metric that does seem to be useful.
dave
Earl Geddes has done some recent research which estalishes that using proper scientific method. He has also come out with a metric that does seem to be useful.
dave
planet10 said:
"irrelevant", "useful", etc.
It all depends on your perspective. We will not be able to find a measurement that will be a perfect indicator of sonic performance for all of us in all of situations.
From that perspective, a useful measurement is just as useful as an irrelevant measurement.
The beauty of a measurement, or scientific theories (valid ones at least) in general, is that they will help us understand certain situations. Another way to put it, those valid scientific theories will fail in other situations: Einstein's relativity theories, for example, fail miserably in microscopic scales where quantum theory excels. And vice versa.
does that mean we should all go out and throw einstein into the trash? I certain hope so, so that I can get a good collection of great works by Einstein when I come to your house to collect the trash, 🙂.
The same thing is true here: you will not be able to find a measurement that works in all situations for all of us. In other words, a good, valid measurement will fail from time to time. The goal for us is to find one that works in as many situations. But more importantly, we should know when to rely on what measurement.
It is foolish to throw that measurement into the trash simply because it will fail from time to time.
Of course, there is nothing to prevent us to be foolish: you have to right if you so decide.
I hope you all have a scientific and reasonable approach to this "measurement delimma", as ASKA does.
tlf9999 said:
The single measurement THD number is one that has NO correlation with what things sound like -- ie does not work in any situation -- so can only be considered a waste of time. The spectrum that comes before the collapse into a single number can be useful thou (ie the data that is generated before the marketing guys collapse it into a sound byte), but needs an informed mind to interpret.
dave
planet10 said:
If you were rigorous, you would have provided sound evidence along with that claim of yours.
Without any evidence, a claim is not worth the bits that carry it. More importantly, it adds nothing to an otherwise intelligent discussion.
tlf9999 said:
I already provided a reference... go look up Earl Geddes work.
And i know you cannot provide a reference that shows THD (single number) has any relevance to sonics because one does not exist. If you believe it is so, then sadly you have been hoodwinked by the marketing guys.
dave
planet10 said:
it isn't exactly helpful in a discussion to base your arguments on "go read someone's work", in this age of information overflow. You should at least give some reference as to what the author found and how s/he found that, which I believe is common curtesy - something in great shortsupply these days.
planet10 said:
I have tons of reference in support of that. You will just have to google to find them on yor own.
🙂
tlf9999 said:
As i said, he showed -- using scientifically valid experiments -- that there is no correlation between single number THD & sonics.
??? I've been looking for 30 years & haven't found any. Just the opposite. What i have found is stuff that pushes toward support of what Mr Geddes experiements show & what my personal experience has been. ie THD (single number) is a meaningless metric.
dave
LMAO
Mongo like when someone do silly like this:
Mongo want to see him have cake and eat it too....
Mongo like when someone do silly like this:
Mongo want to see him have cake and eat it too....
Re: LMAO
Good job, Mongo.
I like it when people are so humor-challenged.
🙂
bg40403 said:Mongo want to see him have cake and eat it too....
Good job, Mongo.
I like it when people are so humor-challenged.
🙂
I apologize in advance to the sincere users of this thread. I can't help myself.
tlf9999, do us a favor, contribute or go away.
That equates to "I know but I won't tell you" and is so shallow.
tlf9999, do us a favor, contribute or go away.
Re: I apologize in advance to the sincere users of this thread. I can't help myself.
Hi, servicing one's medicine right back to its right inventor.
bg40403 said:
Hi, servicing one's medicine right back to its right inventor.
Stop it, you two.......!
Tlf, the Earl Geddes work is extremely interesting, I've seen it before. Dave, my thanks for including it in the debate, it absolutely encapsulates the issues.
Here's the reference:
http://www.gedlee.com/distortion_perception.htm
There are connections with the Cheevers work, and Earl's interest in the spectrum is fascinating. Note also how he is able to quote a range of THD measurements. Here's a relevant excerpt, with full acknowledgement to Earl for this seminal work:
Stimulus %THD %IMD GedLee Metric
Phan08.wav 9.6 22.4 .4
Phan09.wav .1 .3 8.3
Phan03.wav 12.5 32.0 4.8
The original digital file, Phantom.wav, is also available for download from the site, undistorted.
To quote Earl: "While "your results may vary" one should normally find no correlation between perception and the THD and IMD measures. A good correlation with the GedLee metric is evident."
You need to visit the site to download and hear these files. You soon realise that Phan08 is good sounding, yet has outrageous THD and IMD. And Phan09 sounds appalling; gritty, noisy, and unappealing, yet the THD/IMD figures are vastly superior. All this flies in the face of conventional audio marketing and should be compulsory reading for any committed audiophile.
I believe this identifies and highlights a feverish audio marketing industry, which has worked assiduously over many decades to educate the buying public into the importance of THD, IMD (and incidentally, slew rate).
Earl is to be commended for his hard work and the convincing substance of that work.
Cheers,
Hugh
Tlf, the Earl Geddes work is extremely interesting, I've seen it before. Dave, my thanks for including it in the debate, it absolutely encapsulates the issues.
Here's the reference:
http://www.gedlee.com/distortion_perception.htm
There are connections with the Cheevers work, and Earl's interest in the spectrum is fascinating. Note also how he is able to quote a range of THD measurements. Here's a relevant excerpt, with full acknowledgement to Earl for this seminal work:
Stimulus %THD %IMD GedLee Metric
Phan08.wav 9.6 22.4 .4
Phan09.wav .1 .3 8.3
Phan03.wav 12.5 32.0 4.8
The original digital file, Phantom.wav, is also available for download from the site, undistorted.
To quote Earl: "While "your results may vary" one should normally find no correlation between perception and the THD and IMD measures. A good correlation with the GedLee metric is evident."
You need to visit the site to download and hear these files. You soon realise that Phan08 is good sounding, yet has outrageous THD and IMD. And Phan09 sounds appalling; gritty, noisy, and unappealing, yet the THD/IMD figures are vastly superior. All this flies in the face of conventional audio marketing and should be compulsory reading for any committed audiophile.
I believe this identifies and highlights a feverish audio marketing industry, which has worked assiduously over many decades to educate the buying public into the importance of THD, IMD (and incidentally, slew rate).
Earl is to be commended for his hard work and the convincing substance of that work.
Cheers,
Hugh
Hi Planet 10,
"The single measurement THD number is one that has NO correlation with what things sound like -- ie does not work in any situation -- so can only be considered a waste of time. The spectrum that comes before the collapse into a single number can be useful thou (ie the data that is generated before the marketing guys collapse it into a sound byte), but needs an informed mind to interpret."
If the THD figure is approaching ZERO, I hazard a guess that there is little to interpret! High End marketing people would love us to disregard measurements completely then their overhyped ( and overpriced) product becomes the superior creation of the 'black art' inner circle - with no science based constraints!
Cheers,
greg
😀
"The single measurement THD number is one that has NO correlation with what things sound like -- ie does not work in any situation -- so can only be considered a waste of time. The spectrum that comes before the collapse into a single number can be useful thou (ie the data that is generated before the marketing guys collapse it into a sound byte), but needs an informed mind to interpret."
If the THD figure is approaching ZERO, I hazard a guess that there is little to interpret! High End marketing people would love us to disregard measurements completely then their overhyped ( and overpriced) product becomes the superior creation of the 'black art' inner circle - with no science based constraints!
Cheers,
greg
😀
Measurements vs sound
Hi, Mark Levinson the well known audio Guru wrote once in his JC-2 brochure: "most standard specs are meaningless"
The Crown IC-150 had incredible low THD and IM specs but sounded lacklustre especially on harp and guitar.
The new GAS Ampzilla 2000 amp has a set of very nice measurement graphs, yet I have no idea how it really sounds on my loudspeakers.
http://www.ampzilla2000.com/graphs.html (Click on the graphs for legend)
So..................😎
Hi, Mark Levinson the well known audio Guru wrote once in his JC-2 brochure: "most standard specs are meaningless"
The Crown IC-150 had incredible low THD and IM specs but sounded lacklustre especially on harp and guitar.
The new GAS Ampzilla 2000 amp has a set of very nice measurement graphs, yet I have no idea how it really sounds on my loudspeakers.
http://www.ampzilla2000.com/graphs.html (Click on the graphs for legend)
So..................😎
AKSA said:
I just glanced through his presentation and it is indeed interesting (I am not yet convinced that it is valid). Here is a quote from his first couple of pages of presntation:
"They (measures of distortion, THD and IMD) are purely mathematical relationships between the input and output of a system. As such, there really is no reason to believe that they should indicate the perception of the system nonlinearity which they represent".
For the life of me, I cannot understand why being merely mathematical relationships between input and out would invlalidate one's perception of nonlinearity.
Does he suggest that a measurement of (non)linearity should NOT be a mathematical relationships between the input and output of a system?
If so, how's one going to measure (non)linearity of a system? Based solely on input or output?
Doesn't that sound odd?
AKSA said:
my listening impression (without looking at the measurements): both phantom and phan08 sound very close. phan03 has some high frequency distortion and phan09 seems to have a background hissing. Both are audioably different from phantom, as is phan08. So it seems my experience does support the GedLee Metric.
Now, if I were to give you all four versions of those files (without telling you what they are), how many of you can reliably rank order them consistently in accordance with the GedLee metric?
What if we were to use different music materials? that is, is there something special about this particular passage that makes the GedLee metric more successful (and THD or IMD less successful) in measuring music quality?
Re: Measurements vs sound
Would it suprrise you that it came from the czar of marketing, Mr. Levinson?
Another way to put it: do you expect a marketing guy to tell you how you can scientifically assess a piece of equipment's sound quality?
Isn't that like asking a con artist to be honest?
I would venture a guess that no measurement of any kind will reliably tell you how a given piece of amplifier will sound on your loudspeakers to you.
Elso Kwak said:
Would it suprrise you that it came from the czar of marketing, Mr. Levinson?
Another way to put it: do you expect a marketing guy to tell you how you can scientifically assess a piece of equipment's sound quality?
Isn't that like asking a con artist to be honest?
Elso Kwak said:
I would venture a guess that no measurement of any kind will reliably tell you how a given piece of amplifier will sound on your loudspeakers to you.
Re: Re: Measurements vs sound
Yap right, but that is the only thing that matters to me......🙂
And see Borgiorno's line below the graphs.
tlf9999 said:
Yap right, but that is the only thing that matters to me......🙂
And see Borgiorno's line below the graphs.
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