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In Reply to: RE: surrogates posted by fstein on November 10, 2015 at 20:40:27
of finding meaningful measurements that truly correlate to the complex process of hearing music is a noble one. Maybe someday we'll get there. The only way to achieve that goal is to push forward and continue to provide the most thorough examination of which measurements illuminate our understanding with knowledge as opposed to those which simply generate data. And to develop new ones that fill in current gaps.
Richard Heyser, JPL scientist and engineer extraordinaire made the following observation in an article in Audio Magazine:
"I claim that it should be possible to measure audio systems and have those measurements correlate with what we hear out of those systems. We are not doing that now. Our measurements are more precise than ever, but our understanding of what those measurements mean to the way a system "sounds" is still hazy.
I further assert that we are locked into that dilemma because we do not truly understand the meaning of those technical concepts which we now use. I don't think I can be more blunt about the matter."
Well said, sir. JA, stay the course.
Follow Ups:
Richard C. Heyser died in 1987, so the article was apparently published posthumously in 1988. Surely the understanding of how measurements of equipment relate to perception has advanced since then.
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"A fool and his money are soon parted." --- Thomas Tusser
share with us all the advancements.
What new metrics are available for amplifiers?
I am not convinced that any new metrics are needed to make good amplifiers sound the same when operated within their linear limits. That's about how Arny Krueger put it.
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"A fool and his money are soon parted." --- Thomas Tusser
He also said "Amps don't have harmonic distortion." Do you believe that too?
Here's what Arny said:
"Amps don't have harmonic distortion. They have nonlinear distortion, which is sometimes crudely measured using tests commonly called "Harmonic distortion".
I am not an EE, but he is, and I presume he knows what he is talking about. Perhaps you should try to understand what he said.
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"A fool and his money are soon parted." --- Thomas Tusser
I'm an EE too and he's not speaking my language. His statement makes no sense at face value, because harmonic distortion will result from any non-linearity. It's not the only form of distortion, but it's often the biggest.
Categorically speaking, linear distortion is just the deviation in frequency magnitude and phase response. These are the deviations that can be caused by a linear transfer function.
Categorically speaking, non-linear distortion is every other deviation that correlates with the signal, which distinguishes it from noise and interference which are deviations that are uncorrelated with the signal.
If you stimulate a non-linear system with a single pure sine wave at frequency f, all distortion products will occur at multiples of f. This is harmonic distortion.
If you stimulate a non-linear system with a multiple sine waves at frequencies f1,f2,f3,..., the harmonic distortion products will occur at multiples of f1,f2,f3,... Also, the sine waves will intermodulate at the sum and difference frequencies. That is a mix of harmonic distortion and intermodulation distortion.
You can generalize the above to any signal.
At first I wasn't sure what point he was trying to make by distinguishing harmonic distortion from non-linear distortion. I thought he might be suggesting that THD and/or a plot of the harmonic distortion spectrum is insufficient to characterize amplifier distortion. But nope, he seems to think that the only distortion that matters is clipping (which is harmonic by the way).
I don't know where that leaves IM distortion in its various forms. If Arny is trying to suggest that harmonic distortion is negligible but non-linear distortion is not, that only leaves IM distortion in its various forms. That plays right into the hands of Otala, Jung, Curl, et al who have been pointing out for a long time that high NFB designs with insufficient OLB that minimize THD produce unwanted TIM/SID. But I'm quite sure that's not what Arny thinks.
I suggest you ask Arny Krueger what he meant.
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"A fool and his money are soon parted." --- Thomas Tusser
I am not convinced that any new metrics are needed to make good amplifiers sound the same when operated within their linear limits.
We'll necessarily ignore your earlier comments:
Surely the understanding of how measurements of equipment relate to perception has advanced since then.
It hasn't.
That's about how Arny Krueger put it.
Yes, that's exactly what he thinks.
I just bought two 300 wpc power amps with balanced I/O and 4 ohm driving capability from a well-known and highly regarded manufacturer for less than $100 each shipped to my door.
I'm sure he did. Clearly, he couldn't care less about the reproduction of live, unamplified music. :)
Oh, I see. You go by the price!
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"A fool and his money are soon parted." --- Thomas Tusser
when you set the performance bar at your ankles. :)
Yeah, that Pyle Pro line is a real giant killer!
Thanks for finding another amusing story about Arny.
I just went with what YOU said, and the only thing you brought out was the price of the amplifier.
Your reading comprehension is not that good. The discussion was initially about what relation measured results (in general)have to do with perception, and I made remarks about a particular subset of measured results, those for amplifiers. This logical point seems to have escaped you.
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"A fool and his money are soon parted." --- Thomas Tusser
...and the only thing you brought out was the price of the amplifier.
There is a threshold of investment for many kinds of objects that vary widely by performance below which there can be no comparison. How about that $12,000 car that outperforms a McLaren P1?
Right? Are you serious?
I made remarks about a particular subset of measured results
Not really. You pointed to a series of posts by Arny without quoting which "remark". If you mean this:
"At this point, a very high percentage of all properly designed SS power amps including PA amps, and mainstream AVRs can be reasonably expected to sound the same if you turn of all of their DSP functions."
We'll continue to disagree. Sorry if you are likewise unable to hear such differences.
"Sorry if you are likewise unable to hear such differences."
I appreciate the sentiment. However, I am not at all sorry I can't "hear" differences between accurate amplifiers driven driven within their design limits. This saves me endless worries which would interfere with my enjoyment of recorded music and drama.
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"A fool and his money are soon parted." --- Thomas Tusser
However, I am not at all sorry I can't "hear" differences...
Neither could my mother. She was quite content listening to her clock radio.
This saves me endless worries which would interfere with my enjoyment of recorded music and drama.
Why would you have *worries* about hearing more of what's in your recordings? I consider it the joy of hearing a more realistic perspective. :)
When you get around to actually proving that you or anyone else can ear the differences between accurate modern amplifiers driven within their design limits get back to me.
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"A fool and his money are soon parted." --- Thomas Tusser
or you don't.
Your condition does make component selection far easier - everything works the same!
"or you don't."
That is actually quite ambiguous. Perception is affected by many things, and it is quite possible to perceive differences when in fact they are not detected. To "hear" can mean to perceive, but to "hear" can also mean to detect. If anyone is actually interested in determining detection thresholds, that is where controlled blind tests come in.
"Your condition does make component selection far easier - everything works the same!"
That is hardly correct and it is really a rather silly thing to say.
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"A fool and his money are soon parted." --- Thomas Tusser
That is actually quite ambiguous.
Only to those you don't get it. :)
I do get it. You audition electronics, form preferences, and don't care whether your preferences actually correspond to audible differences. That's fine with me.
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"A fool and his money are soon parted." --- Thomas Tusser
with the mediocre my friend. :)
for most modern ss amps is below the threshold of audibility....There's a large cash prize waiting for those who contend they can hear differences, yet no one has stepped up and claimed it...How illuminating...
try it! you know you want to!
Edits: 11/16/15
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