Pavel,
The older standard for accoustics was if I remember correctly 10 micropascals. In some accoustics it is 1 micropascal supposedly only for underwater work but has drifted into gases for some work usually regard ultrasonics, sonar or gizmos like medical scanners.
Then there is sound intensity in air which uses the same reference as Sound Power Level which is 1 picowatt.
So basically SPL is often meant to mean Sound Pressure Level, but it is easier to use the small "a" after the "dB" to avoid confusing it with Sound Power Level if no weighting is being used. BTY "C" is not flat frequency response as often assumed.
The older standard for accoustics was if I remember correctly 10 micropascals. In some accoustics it is 1 micropascal supposedly only for underwater work but has drifted into gases for some work usually regard ultrasonics, sonar or gizmos like medical scanners.
Then there is sound intensity in air which uses the same reference as Sound Power Level which is 1 picowatt.
So basically SPL is often meant to mean Sound Pressure Level, but it is easier to use the small "a" after the "dB" to avoid confusing it with Sound Power Level if no weighting is being used. BTY "C" is not flat frequency response as often assumed.
Not exactly. The effect, if we can call it that, also showed up on simulations done with EM modeling software. This was done by another person (not the inventor).
The simulation shows that it works above 100% efficiency when the current is tuned to a narrow, specific range.
Also notice there are two independent secondaries with two independent loads. It looks like one load sustains the other and the reciprocity to the primary is removed. Too good to be true?
I am posting this attachment here with the same filename as when I received it from Mr. Thane Heins in 2012.
-Alex
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Now you expressed it correctly and I agree with you.
The reference of comparison in your previously quoted sentence (from post # 10160) was missing, that’s why I made the remark.
That’s correct.
If you were intrigued by Rod Elliot’s test, please note that all the logic against A weighting in Rod Elliot’s article is equally applicable to the ITU-R_468 noise weighting.
I wrote “No” because to the best of my knowledge, only on some microphone specs is the self-noise (or equivalent noise) been referenced to acoustic noise measurements standards either A weighted or ITU…
On all other audio reproduction components (cartridges, reel tapes, cassettes, R2R players, cassette players, CD players, A/D converters, D/A converters, preamplifiers, amplifiers, headphones, loudspeakers), the noise measurement is done without reference to such weighting. (SNR, EIN, spectral content, hiss, hum ect).
If you have information on the use of A weighting of noise on audio home reproduction equipment, please provide.
I am sorry if you’ve interpreted my reply to your post as negative.
No. “C” is not flat.
“Z” is
George
George,
"Z" is +/- 1.5 dB from 10 to 20,000 hertz and unspecified above that. Of course I have yet to see anyone actually use it! I believe that it really only started this century.
"C" is pretty much the one that has been used when folks want flat response as it was the closest to it for most of the time when the literature I am familiar with was researched and published.
"B" from my view was committe compromise and never found much use.
"Z" is +/- 1.5 dB from 10 to 20,000 hertz and unspecified above that. Of course I have yet to see anyone actually use it! I believe that it really only started this century.
"C" is pretty much the one that has been used when folks want flat response as it was the closest to it for most of the time when the literature I am familiar with was researched and published.
"B" from my view was committe compromise and never found much use.
I don't know what you mean - the Fletcher-Munson curves are meant to plot our sensitivity to signal at various levels & frequencies - plotted from listening tests. The A-weighted plot is derived from the Fletcher-Munson plots - therefore if the ITU-R 486 deviates from this A-weighted plot (Flecther-Munson plot) then my original statement still stands & is correct "You mean that we can see it shows that the ITU-R 468 curve deviates from the A Weighting curve below about 80Hz ect… Not that we are more sensitive to noise at these frequency sections"
Where do you find a problem with this original statement?
That's what I originally said & reiterated above - not sure why you disagreed with it first time around & now agree with it?
Can you spell out this logic as I don't see what you are talking about? If you mean that the A-weighting curve only applies to one SPL level (~30dB on F-M plots) then what level do you think the ITU-R 486 curve applies to?
I gave you a link to the BBC (British Broadcasting Corp) who researched noise in audio equipment & the resultant plots from listening tests was the genesis of ITU-R 486.
Here is the ITU standards paper on this https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.468-4-198607-I!!PDF-E.pdf
Just because the standard is not used widely (the US never adopted it) doesn't mean diddly squat, in my book - it's either a meaningful & more correct evaluation of our subjective sensitivity to noise or it's not. I believe it is meaningful & therefore worth bearing in mind
You are now off the fairway in the rough & have lost sight of the hole.
It's simple logic - what is comes out of our playback systems is a signal comprising of both recorded signal + noise plus the added noise of the reproduction system (many sources). If we are more sensitive to noise then the accepted wisdom (from the F-M plots) then let's take this into account in judging what's above/below audibility
Nah, i was just making a general point to Scottjoplin - you know, the sniper on the grassy knoll
Someone posted news which led to this recent paper about a "magnetic diode".
As you can see there is a clear parallel between this paper and what I have posted. There is some interesting data in the stuff I posted. Someone could try to replicate it. I am not too excited about it; It´s been 8 years and no news about this.
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I just like to remind people that the ear does not distinguish noise from signal in any form of engineering weighting measurement methodology.
the cilia bend back to the sum total and the sum total, like the surface of a water system modulated by big and small vibrations....this includes random noise and distortions, along with the signal. The ear's methodology hears the sum total and hears the micro modulations that ride minutely on the signal. Those micro modulations are not at the bottom, that's engineering thinking and methodology. "distortion is low, everything is ok!"
It is difficult to be more wrong than this for so long a time.
For at least a decade now I've been proposing a methodology that involves looking only at the positive peaks in a level of maybe about 10% of the full signal, and working hard to preserve absolute levels of perfection in the clocking of such a signal as the peaks would be in relation to one another.The clock must have low jitter in as wide a bandwidth as possible and the extension of that bandwidth toward DC being the critical part. In both measurement hardware and in reproduction hardware.
Forget about the other 90% of the signal. It is meaningless to the ear.
Eg, people like horns, calling them low distortion. If you look at the distortion of a horn, it is 15% to maybe 40% distortion. Yet people still feel they are accurate and low distortion.
Engineering analysis show that the positive peaks are the only thing horns come close to getting right.
There is far more other correlation across the industry and in other areas of research..
So change your method to reflecting the way the ear works and you'll finally achieve perfect correlation so you can really take a look at what is going on in there.
The strange thing about snake oil, is that snake oil is a real thing, and it works as it should. Medically and so on. Oddly enough. Yes, snake oil is a functional, real item.
I get what you are saying but the irony is not lost on me. Science marches on in this tug of war between chaos and order (quantum vs deterministic), but far more blood is shed than necessary due to the fallible man in the mechanism.
Individuality informs us, shapes us, and is likely our greatest advantage, but also likely our greatest enemy re moving forward.
Identical things are all dead together, as commodities are, and as human fallacies wish others to be.... but 'all individualism' has no order so that intelligence cannot arise. Both ends of the spectrum are dead things. Life and self reflection (the intelligence counterpart) exists solely in the middle, bouncing about - between those extremes.
Perfection is a death no less sure than chaos. Keep walking. Keep moving.
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No surprise some have withstood decades of irreproducability. Back in the day this thread was interrupted more frequently by these articles, I could list you a few. My favorite is a perpetual motion device that actually got past the patent office (IMO) because they simply did not claim connecting the input to the output (i.e. the perpetual motion itself). The Tom Bearden Website
Most of the demonstrations of "working" are cloaked (sometimes literally) and many are very easy to see through. It seems no matter how carefully the plans are disclosed non-believers can't get them to work. Of course you will find many conspiracy stories here. AFAIK only one, Steorn, finally fessed up as a put on.
That statement had me laughing hysterically. Thanks.
On occasion, I'm asked how much I would charge for one of my wooden gear clocks or house renovation work.. My answer is always "you can't afford me".
Even at two dollars an hour!
There is, and you stated it.
While they did state it was a lossy process, they left the bulk of that understanding on the cutting room floor. They are driving the copper with a motor, putting energy into the system. They've not included that transference in their discussion, so have neglected one of those there thermo equation things. Conservation of energy.
I was using this effect back in the seventies. But instead of copper, aluminum. And instead of a lock in amplifier and matrix math, a linear force vs displacement apparatus. The readout was a simple deflection based device with a curved scale.
It was in the dash of my 72 ford maverick.
Jn
Modify a AP system's software suite appropriately and the correlation should finally stick out like a sore thumb.
This might make things fun for a while, maybe a decade or two, as audio gains solid correlation in it's extreme pronouncements (tweaks, cables, etc) and so on. A shiny thing on a hill in the final glory march into perfection. Then encircled, and ticked off on the 'to do' list,...it becomes a commodity, and moves to being a dead thing. Audio would then be over.
And the types here, at this time, would have to find something new to gnaw on.
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Interesting, that was exactly my first impression.
I can see a spinoff company, working in the lab, writing obscure ill defined papers, with the continuous call for "more money from investors" as we're so close, look at the demo's..
If they show up at my doorstep hovering above the ground in a Delorian,
perhaps I'd change my mind.
Jn
Yes, auditory perception differentiates foreground from background, sound objects from noise, one sound object/stream from another - what the brain receives is just a continuous stream of signals which have no meta information with them - it has to sort out & make sense of these signals & the data is usually insufficient to find a unique scenario that they map to so we are constantly guessing our way in the audio world (similar with other perceptions too).
That is one of the great mistakes made here - that our auditory system is something like our engineering systems - it's not.
It explains why we don't notice the gorilla in the room when our focus is on something else in the same field of vision - it's why we have to train for blind testing - it's why blind testing uses statistics as we second guess our auditory perception in the absence of other confirming signals.
OK, if I understand - you are saying that the low level detail is the important stuff - is that correct & getting the timing & amplitude relationship between these low level details is crucial?
Are you saying that the low level details are what a horn gets right?
I agree with the last paragraph completely & it's what I've been saying all along - understanding of auditory processing can give us clues as to what we are perceiving in our audio systems & further analysis through designing new measurements can advance our systems
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