When I was a young'un I was proud of the fact that I could identify every make and model by a mere glimpse of the shape of a taillight -- how one's interests change over the years!!
Yes. The snag is that their results are the consequence of subtracting two big numbers from each other. Everyone knows that this results in few significant figures in the answer - even less when a minimisation technique is used. The results could depend on details of their data fitting algorithm - I assume this is entirely automatic; if it involves human intervention then their results may contain no significant figures at all.fas42 said:
Exact replication won't happen, as for that they would need to reproduce exactly the same clock drift and jitter.
There simply isn't enough detail in the paper to judge exactly what they are doing. Hence it should be regarded as marketing rather than science.
The first paragraph of theirs which you quote in post 9358 is a set of unsupported assertions of audiophile myths, presumably intended to separate readers into 'us' and 'them'. Their hope is to sell to 'us'; people like 'them' obviously have defective hearing or insufficiently discriminating systems.
Control system theory is the same for both applications, as they make clear with the "dog chases rabbit" analogy. I'm sure they must have looked at current audio systems test methods and recognised the maths. They haven't made an honest mistake, they cannot possibly be so ignorant.
I wouldn't be surprised to find that defence contractors sometimes tell lies. They sensationalise vulnerabilities and sell countermeasures.
Many years ago I used to assume that people doing their day job were smarter than me, and knew their own business better than me. Then I discovered that often wasn't the case so I assumed that I was as good as them. I now have a piece of paper which says I am smarter than most people; experience (in industry, academia and everyday life) has taught me that many people don't know their own business. I am therefore no longer surprised when people make a mess of things they are paid to do (and sincerely believe they can do) properly.
Now it may be that the technical stuff which would convince me that they did understand what they were doing has been airbrushed out of what is essentially a marketing tool. I don't know. I can't read what isn't there.
Now it may be that the technical stuff which would convince me that they did understand what they were doing has been airbrushed out of what is essentially a marketing tool. I don't know. I can't read what isn't there.
You hit the nail on the last point. You don't know what they were specifically contracted to do, you don't know what was reported, you don't know how it was qualified, you don't know what was extracted. All you know is the marketing spin and the "interpretation" of selected raw data by someone in the business of selling questionable gizmos to gullible consumers. Test labs do and report what they're told to do and report.
If one is totally unfamiliar and inexperienced with working in a lab and actually getting one's hands dirty taking measurements, one can easily be lulled into having some faith in a marketing blurb with all sorts of pretty graphs and pictures.
If one is totally unfamiliar and inexperienced with working in a lab and actually getting one's hands dirty taking measurements, one can easily be lulled into having some faith in a marketing blurb with all sorts of pretty graphs and pictures.
Valve rollers measure too. Using conventional techniques, the effects of differences between valves in the context of a simple sound system can be clearly identified. The usual measurements of the valves themselves tell only a small part of the story. I found that the dynamic impedance of the grid can vary a lot between similar pentodes in triode mode, for example, and that can make a difference to frequency and phase response as well as distortion characteristics.
They are looking for the perfect presentation, BTW. Not euphonic colouration or perfect reproduction. I have some respect for that attitude, even though I don't quite understand how it plays out in their heads, or why it's taking so long to get there.
It's not rocket science!
I don't have so much faith in the ignorance of others.
I accept the point that we don't know who's responsible for the lie.
I think that is a good answer ( Mr Plastic ) . My guess was that the plate resistance as some call it was the question . Although not in triode my UL feedback is above 43% so is more like a triode .
If anyone is interested could they look down the pages of the link showing 6550 with kickback diode . It looks safe to me to do this . I dare say in PP it might flash over ?
6550/KT88/EL34 single ended amplifier
If anyone is interested could they look down the pages of the link showing 6550 with kickback diode . It looks safe to me to do this . I dare say in PP it might flash over ?
6550/KT88/EL34 single ended amplifier
I have quoted this before so forgive .
"A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools."
- Douglas Adams, author (1952 - 2001)
It covers all questions about people that quote . The other one is " what history teaches us is that history teaches us nothing " . Myself , I am a bit foolish . It is how I learn .
My boss was highly educated with many pieces of paper . All of his ideas were rejected up to the point of when he was needed to get the company out of trouble . His son called the ones who thwarted him the Club of Uncles . The whole world is run by them.
"A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools."
- Douglas Adams, author (1952 - 2001)
It covers all questions about people that quote . The other one is " what history teaches us is that history teaches us nothing " . Myself , I am a bit foolish . It is how I learn .
My boss was highly educated with many pieces of paper . All of his ideas were rejected up to the point of when he was needed to get the company out of trouble . His son called the ones who thwarted him the Club of Uncles . The whole world is run by them.
Periodic impulse response measurement can be very precise; I use them all the time for measurements used in generating system alignments, and demonstrating effectiveness of the alignment:
To get above result woofer and tweeter were measured independently, but in time coherent fashion. Equalization, crossover, and crossover timing were created based on measured results. Settings were applied, and terminal polarity of tweeter reversed, and measurement made producing above result.
Notch is about -50dB, 0.3% residual energy at crossover point.
It isn't rocket science, at least not 21st century.
Two completely different clocks may be used, and a third clock can be in the middle. Only important point is that drift of clocks over measurement intervals must be very small.
Periodic sources can be made out of virtually any signal. Of course it is sensible to use well defined broadband signal. White noise, pink noise, swept sine may all be used very effectively. Periodic bursts also work great.
An externally hosted image should be here but it was not working when we last tested it.
To get above result woofer and tweeter were measured independently, but in time coherent fashion. Equalization, crossover, and crossover timing were created based on measured results. Settings were applied, and terminal polarity of tweeter reversed, and measurement made producing above result.
Notch is about -50dB, 0.3% residual energy at crossover point.
It isn't rocket science, at least not 21st century.
Two completely different clocks may be used, and a third clock can be in the middle. Only important point is that drift of clocks over measurement intervals must be very small.
Periodic sources can be made out of virtually any signal. Of course it is sensible to use well defined broadband signal. White noise, pink noise, swept sine may all be used very effectively. Periodic bursts also work great.
measurements vs reality
"increasing trend over the last years, where car manufacturers are lying about mileage" "..bmw being one of the worst.."
measurements vs reality 2
*measurement devices should be calibrated yearly, if not stated otherwise
* device measurement accuracy 0,1..5%?
* device measurement bias, error..
"increasing trend over the last years, where car manufacturers are lying about mileage" "..bmw being one of the worst.."
measurements vs reality 2
*measurement devices should be calibrated yearly, if not stated otherwise
* device measurement accuracy 0,1..5%?
* device measurement bias, error..
The problem with car manufacturer measurements are hardly a mystery. They measure highway consumption at a speed of 90 km/h. I would imagine at that speed, most get it about right.
What is wrong here is that European highways (motorways) are generally limited to 110 to 130 km/, average 120 km/h, and only in Germany, there are some sections which are unregulated. When cars are ran at 120 km/h, they quite normally use up 30-40% more fuel than at 90 km/h, so the problem is in the basic model used.
Everybody knows that, yet the pressure from car companies is to keep it, so they can quote true but still unfair numbers. Not many will drive at 90 km/h where they can legally drive 120 km/h, so the consumption quoted may be true, but is completely unrealistic.
Even more interesting are the consumption figures of supercars at supercar speeds. Germany's Auto, Motor & Sport tested the Porsche Cayenne Turbo at just uner its tops peed, at 270 km/h (168 mph). The consumption was 68 litres/100 km (app. 15 US gallons per 96 miles, or 6.4 miles/gallon).
Them 500 horses gotta eat, dude!
What is wrong here is that European highways (motorways) are generally limited to 110 to 130 km/, average 120 km/h, and only in Germany, there are some sections which are unregulated. When cars are ran at 120 km/h, they quite normally use up 30-40% more fuel than at 90 km/h, so the problem is in the basic model used.
Everybody knows that, yet the pressure from car companies is to keep it, so they can quote true but still unfair numbers. Not many will drive at 90 km/h where they can legally drive 120 km/h, so the consumption quoted may be true, but is completely unrealistic.
Even more interesting are the consumption figures of supercars at supercar speeds. Germany's Auto, Motor & Sport tested the Porsche Cayenne Turbo at just uner its tops peed, at 270 km/h (168 mph). The consumption was 68 litres/100 km (app. 15 US gallons per 96 miles, or 6.4 miles/gallon).
Them 500 horses gotta eat, dude!
I own matched pair of microphones circa 1996; When one has response flattened using full range source in closed coupler, and the 2nd microphone is then substituted into coupler, returned response matches original calibration chart to within tenths of a dB across entire useful bandwidth. When microphone roles are reversed, the second microphone also matches original calibration chart to same degree.
dvv;
The problem with your post is it has zero relevance to this forum, or to this thread topic.
Horses gotta eat, some posters here just gotta spew garbage.
My point was, since you obviously didn't get it, is that an industry, in this case auto but by no means limited to it, as the audio industry does the same, is to promote tests and measurements which enable them to show off their products, at the cost of any real relevance.
The audio industry still promotes classic static distortion measures as its holy grail, even after it has been shown that it is, at best, vaguely relevant to the sound. Just as the auto industry promotes ridiculous speeds for measuring fuel consumption. It'sd by no means a matter of science, both industries could do way better, it is a question of economics. They will always tend to use whatever makes their product appear to be better for the masses.
The audio industry still promotes classic static distortion measures as its holy grail, even after it has been shown that it is, at best, vaguely relevant to the sound. Just as the auto industry promotes ridiculous speeds for measuring fuel consumption. It'sd by no means a matter of science, both industries could do way better, it is a question of economics. They will always tend to use whatever makes their product appear to be better for the masses.
The true irony is that there are threads on this forum where recognised people in their field are debating whether subtle changes in topology will mean that, say, 0.0002% distortion will be achieved versus 0.0005%. This is living in a theoretical dreamworld, once the circuit is attached to real power supplies, grounding layouts, etc, these wonderful performance figures evaporate into nothingness.
Yet, this is considered to be the 'proper stuff' ...
Yet, this is considered to be the 'proper stuff' ...
@fas42 - you get me thinking...
I sometimes think back to the stuff we had back in the 1950's-'60's - like Quad II, Williamsons, Mullard 5-20 and 5-10, Quad 303, etc. They would have had (guessing) distortion figures of 0.05-0.1%, frequency response 30c/s-20kc/s +/- 0.5dB. Those amps sounded, and still sound, very good. 40 years ago I heard heard Quad IIs playing into ELSs in a small concert hall, and I thought then "this is as good as it needs to get". A fellow-student was given a 303, Thorens, and decent loudspeakers by Quad, which ended up being looked after by me for 6 months, and I felt the same about them.
So, I think, did the science of audio reproduction get as good back then as it needs to be for beings with a limit to their hearing (Iknow damned well that I can't hear 20kc/s, or distortion below .05%). There may be people out there who can hear any distortion above 0.0005%, but they must lead a tortured existence, and I've never knowingly met one.
Not decrying the never-ending striving for technical improvement, but it has perhaps become just a fanatical hobby - like stamp-collecting. Both are fine, providing you don't confuse them with living.
Just saying....!
I sometimes think back to the stuff we had back in the 1950's-'60's - like Quad II, Williamsons, Mullard 5-20 and 5-10, Quad 303, etc. They would have had (guessing) distortion figures of 0.05-0.1%, frequency response 30c/s-20kc/s +/- 0.5dB. Those amps sounded, and still sound, very good. 40 years ago I heard heard Quad IIs playing into ELSs in a small concert hall, and I thought then "this is as good as it needs to get". A fellow-student was given a 303, Thorens, and decent loudspeakers by Quad, which ended up being looked after by me for 6 months, and I felt the same about them.
So, I think, did the science of audio reproduction get as good back then as it needs to be for beings with a limit to their hearing (Iknow damned well that I can't hear 20kc/s, or distortion below .05%). There may be people out there who can hear any distortion above 0.0005%, but they must lead a tortured existence, and I've never knowingly met one.
Not decrying the never-ending striving for technical improvement, but it has perhaps become just a fanatical hobby - like stamp-collecting. Both are fine, providing you don't confuse them with living.
Just saying....!
A bit more of a lookaround - yes, the Vertex stuff appears to have gone into the twilight zone ... it would have required someone to have been paid to make the serious effort needed to get something more substantial on the table, which in our world, obsessed with the bottom line, means it's died in the bum ...
DiffMaker is moving in the right direction, but it hasn't been developed enough - it needs to be more robust, have more 'smarts', be capable of remaining firmly aligned with the intrinsic waveform no matter how much it wobbles or misbehaves in ways that are not audibly significant, while still filtering out the interesting anomalies. In other words, getting just a little bit closer to how the human hearing system operates,
DiffMaker is moving in the right direction, but it hasn't been developed enough - it needs to be more robust, have more 'smarts', be capable of remaining firmly aligned with the intrinsic waveform no matter how much it wobbles or misbehaves in ways that are not audibly significant, while still filtering out the interesting anomalies. In other words, getting just a little bit closer to how the human hearing system operates,
That is something I would toss into the simulator to check. It looks almost like a flyback power supply. There is already capacitance from the screen to the cathode to hold the charge. And the sudden change in current through the transformer is not good if linearity is on your roadmap. It may add some nice harmonics to "tune up" your tone.
The problem with car manufacturer measurements are hardly a mystery. They measure highway consumption at a speed of 90 km/h. I would imagine at that speed, most get it about right.
What is wrong here is that European highways (motorways) are generally limited to 110 to 130 km/, average 120 km/h, and only in Germany, there are some sections which are unregulated. When cars are ran at 120 km/h, they quite normally use up 30-40% more fuel than at 90 km/h, so the problem is in the basic model used.
Everybody knows that, yet the pressure from car companies is to keep it, so they can quote true but still unfair numbers. Not many will drive at 90 km/h where they can legally drive 120 km/h, so the consumption quoted may be true, but is completely unrealistic.
Even more interesting are the consumption figures of supercars at supercar speeds. Germany's Auto, Motor & Sport tested the Porsche Cayenne Turbo at just under its top speed, at 270 km/h (168 mph). The consumption was 68 litres/100 km (app. 15 US gallons per 96 miles, or 6.4 miles/gallon).
Them 500 horses gotta eat, dude!
In the US the MPG numbers are derived from the emissions testing process. They calculate back from the exhaust output over the programmed driving cycle. Even though they are not measured by fuel consumption directly they are remarkably accurate in practice. Some manufacturers get caught cheating (Kia had to repost new numbers and had to reimburse customers over the issue: https://kiampginfo.com/ ).
I could burn through 6.4 MPG with a GMC Suburban (455 ci) and horse trailer at 65 MPG, I don't need $60K of German machinery to do that (from the land of wretched excess).
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