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In Reply to: RE: Design evolution over years for predominant second harmonic posted by 6AS7_6SN7 on April 29, 2017 at 02:58:19
Richard C. Heyser whom will take to task those in the 'subjective camp' and 'objective camp' and KINDLY humiliate both thought processes with the closest thing to proof I have ever found. These 9 pages WILL wet your whistle.Edited for accuracy
The Mind has No Firewall~ U.S. Army War College.
Edits: 04/30/17Follow Ups:
Beautiful paper indeed!
Just an addendum.
The Hilbert theorem (for linear networks), which states that amplitude response and frequency response are related by the Hilbert transform, only applies to the so called 'minimum phase' linear networks.
To make a long story short, a "minimum phase" network is a network where there is only one energy path from input to output.
Most microwave networks (filters) are not of this type, as usually there are multiple paths of energy from input to output via interconnected cavities.
SAW filters are not "minimum phase" too.
Most digital filters are not "minimum phase" either.
The frequency response of you listening room (i. e. from each speakers to each of your ears (when you are seated somewhere in there) IS NOT "minimum phase", as it is well known that many energy paths, via the inner room reflections, contribute to the hearing phenomenon.
About 25 years ago I published an article "Group delay calculation by scalar instrumentation" where I showed that, provided that you can ascertain the "minimum phase" hypothesis of a device under test (a RF filter for example), then you can accurately calculate the group delay vs. frequency response (which is of utmost importance in all digital systems) based on the measured wideband amplitude response (scalar measurement).
Group delay (i. e. the frequency derivative of phase response) is the time that energy around some frequency takes to travel from input to output.
So I do not feel humiliated, quite the opposite!
ecc230
Richard C. Heyser: "Perhaps more than any other discipline, audio engineering involves not only purely objective characterization but also subjective interpretations. It is the listening experience, that personal and most private sensation, which is the intended result of our labors in audio engineering. No technical measurement, however glorified with mathematics, can escape that fact."
The Mind has No Firewall~ U.S. Army War College.
"No technical measurement, however glorified with mathematics, can escape that fact."
Of course, everyone too lazy or too ill-equipped to make measurements (or perhaps too vain to accept the limitations of their own hearing and interpretation), will love quoting this out of context. Let's just not forget that poor electrical performance, much of which can indeed be objectively measured, will never produce the best listening experience.
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Buy Chinese. Bury freedom.
...didn't quote out of context.
I took from the full quote that objective measurement is important... as is the interpretation of said measurement with one's eye on on the intended end-use. That is, the listening, which we should recognise is personal. And not to forget that.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
You assume much If, you believe am quoting out of context.
Perhaps this will help.
The Mind has No Firewall~ U.S. Army War College.
Many heated discussions here have centered on individuals' assertions that - based on their hearing and nothing else - they know what's best for everyone. These long-winded and perpetually repeated ramblings emphasizing subjective superiority should offend anyone interested in designing and building quality tube gear. I was merely pointing out that your favored author offers undue credibility for such folks if the dissertation is not considered in its entirety.
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Buy Chinese. Bury freedom.
"Let's just not forget that poor electrical performance, much of which can indeed be objectively measured, will never produce the best listening experience."
Unless it does in the ears of the uneducated listener.
And that's the rub. If someone likes the sound of a system, no matter how bad it really is, how can you/I argue with that?
As long as music playback is seen as 100% subjective then there's no way to try to reason..........with anyone.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Moreover, people hear differently, this ...fact, allows me to exercise a large measure of tolerance toward people's preference in sounds that I (personally would deem um, er, peculiar.
The Mind has No Firewall~ U.S. Army War College.
"people hear differently"Yes they do.
But don't we all listen with our own ears?
When we listen to live, unamplified musical instruments we listen with our own ears.
When we listen to a playback system we listen with our own ears, the same ears we used to listen to the real thing.
So if the system is doing a really good job at it's job then shouldn't that be recognized as such by all?
Let's talk about frequency response, just to start with.
If my hearing is down in the upper octave then when I listen to the real thing I hear the highs as being down and when I listen to a playback system, that has an even frequency response, I would hear the highs as being down.
Now wouldn't that be appropriate or should a playback system compensate for the fact that we each hear differently?
So, just in terms of frequency response, each individuals system would be built to compensate to that individuals hearing shortcomings?
So what happens when I listen to live unamplified instruments with my hearing shortcomings? There are no tone knobs on a violin.
I say that playback is not (at it's root) subjective.
The playback either sounds like the real thing or it doesn't (having nothing to do with personal preference).
When trying to get a natural sounding recording of a acoustic instrument, one picks the microphone and the microphone placement based on listening to the instrument in the studio and walking back and forth to the control room listening to the live feed through the control room monitors and comparing the two for sameness.
The determination is subjective (determined by ear) but the objective of the exercise is just that, objective. The live feed through the control room monitors either sounds like the real thing or it doesn't.
Now I have to admit there are not a lot of engineers out there trying to make natural sounding recordings (at least not in the world of rock/pop music).
George Martin famously said (paraphrase) 'we can't have the instruments sound like themselves'
Ringo said 'we have guitars that sound like pianos. What's next, pianos that sound like guitars?'
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 05/01/17 05/01/17
Well said, Tre.
A close friend (75) has decreased hearing above 10K, how much I don't know.
I am 55 and I can hear up to 12.5K then drops like a rock.
So many stress equipment flat out to 20K, I could not care less.
These quibbles of frequency response in an amplifier are on the margin @
best. Best to look at one's speakers and the biggest contribution to poor
sound... the ROOM.
The playback will NEVER sound like the real thing if a full tilt orchestra
or big band is your bag. Much better chance with chamber music.
There are so many variables but first and foremost 'do no harm';
unfortunately, that means building a decent room FIRST with an ear for the
type of speaker one wants to use. Very few approach recreation of music
in that fashion.
The Mind has No Firewall~ U.S. Army War College.
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"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
In other words, only inside an anechoic chamber the measurement of amplitude response gives also an indication of group delay flatness (the lower the ripple, the flatter the group delay). Inside an anechoic chamber, as there are vitually no reflections, there is only one energy path from speaker to microphone/ear (minimum phase).
In all other listening rooms the frequency response measurement taken at one single point of the volume DOES NOT MEAN A THING!
Due to wall reflections the only way to characterize the audio phenomena inside the room is by recording the time domain impulse responses at many points inside the volume in order to find the "eigenvalues", that is, the location where the frequency response from speakers to listener is the flattest (and where group delay flatness is best).
This is the reason why - when looking for non linearities - I personally prefer the sonic signature method by moving the notebook around the room (when a single tone is diffused by the speakers).
With i-phones and a suitable app it is also possible to use white/colored noise and spectrum display, as you know, there are so many ways to be curious and have fun.
ecc230
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