serengetiplains said:
In the final analysis, I agree with you. On the practical side, however, you cannot expect interested audiophiles to test each and every product or gimmick that is marketed. It is incumbent on the designer or inventor to provide reasonable explanation or proof if he wants us to take his product seriously, and I guess he wants that. If he doesn't do that, he cannot hide behind the slogan: "try it before you judge it", IMHO.
Now I promised JC to actually look into those Shakti stones. I checked into those 'dymo'-tests. The differences in 'before-after' were way less than what you would expect as normal test noise. Also, as noted in my earlier post, I found that two of the graphs showed exactly the same curves, although they were presented as two diferent tests. I called it an error, because fraud is such a heavvy word, and, hey, why not give them the benefit of the doubt. But it doesn't really compel me to shell out my hard-earned euri to buy the stuff.
So for me, the case is closed. They had their chance for my money, and failed miserably. Life goes on.
Jan Didden
serengetiplains said:
A pausable explanation is that there lies some sort of advantage or status in understanding things that others don't or have not had a chance of trying yet. If all gear sounded and measured the same, there where no room for audio magazines or reviewers. Again, the god ol placebo (combined with the urge to find something "new") and an other well known effect, the "Emperors new clothes" (does Mag A reviewer have less erars than Mag, B) both make joint force to fuel the business. Manufactuer happy, Mag. happy, (some) and maybe customer happy.
/
Just for the record, dynamometers are what i've done for the past 20 odd years. If your speaking of auto garage dynos and measurements, errors in the 2% to 5% range are probably typical. The auto manufactures (largest dyno users) will demand torque measurements to an accuracy of 0.1% of full scale, and often ask for 0.05%. Speed accuracy is "controlled" to +-1rpm with 16bit measurement accuracy (1/65,000).Magura said:I too have a little experience with dyno testers, a mere fact is that a 1% difference in any test would be discarded by anybody whom wouldnt be paid for prooving something that isnt there. I would go as far as saying that all the way up to 3-4% would normally be discarded as a "null" result.
Magura
Superflow dynos are nowhere near the state of the art.
serengetiplains said:
Yes, you are speculating. Audio reviewers are people who can write entertainingly and help sell magazines and advertising. If they don't do that, they don't have a job. Within the group of successful reviewers, some are very good writers and very competent, others are entertaining and not very competent. And some are so horribly awful that I wonder why anyone would read their stuff.
Actually neither. I described control and measurement accuracy. However, the equipment and measurement instruments used today in industry are fully capable of repeatability and results with the same level of precision.TNT said:
The area where these types of accuracies are most prevailent is in the area of emissions and emissions regulations. If a auto or diesel manufacture fails to pass emissions, they are either fined huge sums of money or not allowed to sell the offending vehicles or engines.
These instuments measure down to the parts per million. Of course these are gas measurements, but the speed and torque (load) can affect these measurements drastically. GM or Daimler would be very upset if they couldn't sell their new cars because the dyno they bought from us would only hold accuracies of 1%.
SY "JE ACCUSE!" ;-) This million dollar thing is a set up in the case of the Shakti Stone. It has AlREADY been checked out legally. Talk to Ben at Shakti, if you want further specific information. Folks, the Shakti stones are fabricated RFI absorbers that work on a transformer principle to convert a passing through RF field into heat.
Is this so hard to understand? Is this in the domain of the 'supernatural' or 'metaphysical'? IF not, I am told that it does not meet the challange criterion put forth by the 'Randi Challange'. This was explained to me, in detail, by Ben, chief designer, at Shakti. He had a lawyer colleague look into it.
Work it out for yourselves, folks.
Is this so hard to understand? Is this in the domain of the 'supernatural' or 'metaphysical'? IF not, I am told that it does not meet the challange criterion put forth by the 'Randi Challange'. This was explained to me, in detail, by Ben, chief designer, at Shakti. He had a lawyer colleague look into it.
Work it out for yourselves, folks.
roddyama said:
Rodd, what do make of this then:
/quote
I have a nice little side business repairing SuperFlow dynomometers, the overwhelmingly dominant dyno in the US. Every magazine article I've ever read used a SuperFlow. The standard SuperFlow is rated at 1000 HP, 10,000 rpm and 800 ft-lbs of torque. The RPM signal is converted to a voltage by a tach chip before being submitted to an A/D converter. The
torque signal is derived from a strain gauge attached to the absorber. This signal is also applied to the same A/D converter through an analog mux. Horsepower before SAE correction is the simple calculation: (torque (ft-lb) * RPM ) / 5252 . This computation is done in an analog multiplier for the analog readout
and by the CPU for the digital readout. So good, so far. But here's the kicker. The A/D converter is an 8 bit unit. That is, it digitizes the incoming signal into one of 256 binary values. For torque, that is 800 ft-lbs / 256 = 3.13 ft-lbs per bit. For RPM, 10,000/256 = 39 rpm per bit. At a constant 6000 RPM, the best HP resolution is 3.5 hp. At a constant 500 ft-lbs of torque, the best HP resolution is 3.7 HP. This lack of precision results in the best theoretical HP measurement at 6000 RPM being +- 3.5 hp. Worst case is 3.5 + 3.7 = 7.2 hp. The root-sum-square (much more representative of the real world) is 5.0 hp. The precision varies, of course, with RPM. The important point is any
horsepower variation less than about 5 hp is meaningless and is more likely attributable to quantitizing error in the electronics. Understand that this does NOT include other systematic error terms such as the errors associated with the analog electronics or the torque sensor calibration. I personally attribute no credibility to differences less than 10 hp.
[snip]
Bottom line - take any claims of small increases in HP due to "tricks" with a LARGE grain of salt.
/unquote
Jan Didden
I don't have any problem with "try it before you judge it" if you can return it after 30 days for a full refund, no hassle. At least two companies, Magnepan and Ohm do this with loudspeakers. This requires considerable confidence on the part of the seller that their product delivers in full measure. Such an approach would much easier and inexpensive for Shakti to use.
John, je te reponds!
Shakti Stones are claimed to be devices that improve the sound of hifi systems. This claim is made on their website, in their promotional material, in their patent, and by various audio reviewers. The microwave absorption is the claimed mechanism, not the claimed effect. Randi's challenge is NOT to prove that they absorb microwaves (a roast chicken absorbs microwaves!), but to prove that they alter the sound of a system by placing them as recommended. That's a paranormal claim and that's what should be tested.
It's an easy test to set up.
It's a million bucks.
What are you waiting for? You could use a new Porsche.
If you win, it's dinner at Slanted Door, your treat.
Shakti Stones are claimed to be devices that improve the sound of hifi systems. This claim is made on their website, in their promotional material, in their patent, and by various audio reviewers. The microwave absorption is the claimed mechanism, not the claimed effect. Randi's challenge is NOT to prove that they absorb microwaves (a roast chicken absorbs microwaves!), but to prove that they alter the sound of a system by placing them as recommended. That's a paranormal claim and that's what should be tested.
It's an easy test to set up.
It's a million bucks.
What are you waiting for? You could use a new Porsche.
If you win, it's dinner at Slanted Door, your treat.
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