Have any of the EE types here looked at the results of a test
of the Shakti Stone's ability to attenuate EMI, posted
on the company's website?

http://www.shakti-innovations.com/emitests.htm

Googling doesn't seem to show any discussion of same in
the audio newsgroups. Since I can't make heads or tails
of the graphs as presented (to answer even
simple stuff like, how big is the measured effect?),
I'm curious to hear the opinions of those who can.

These results, btw, are being used to bolster the claim that
Shakti Stones might work, over on audioasylum, in the
Randi threads.

Steven Sullivan wrote:
Have any of the EE types here looked at the results of a test
of the Shakti Stone's ability to attenuate EMI, posted
on the company's website?

http://www.shakti-innovations.com/emitests.htm

Googling doesn't seem to show any discussion of same in
the audio newsgroups. Since I can't make heads or tails
of the graphs as presented (to answer even
simple stuff like, how big is the measured effect?),
I'm curious to hear the opinions of those who can.

These results, btw, are being used to bolster the claim that
Shakti Stones might work, over on audioasylum, in the
Randi threads.


Well, if you place a piece of metal over a transmitting antenna, you
will perturbate the field pattern of the emissions. Would you think that
putting a piece of sheet metal somewhere around the stereo system would
improve the sound?

The test conducted is really meaningless. If you look carefully, the
received strength is actually higher at the bottom of the band, around
312 MHz.

If they want to prove that effectiveness of the stones, conduct audio
measurements with and without the stones. Measure frequency response,
signal-to-noise ratio, distortion, etc. You know, things that have
something to do with audio.

In article ,
Steven Sullivan wrote:

Have any of the EE types here looked at the results of a test
of the Shakti Stone's ability to attenuate EMI, posted
on the company's website?

http://www.shakti-innovations.com/emitests.htm

Googling doesn't seem to show any discussion of same in
the audio newsgroups. Since I can't make heads or tails
of the graphs as presented (to answer even
simple stuff like, how big is the measured effect?),
I'm curious to hear the opinions of those who can.

These results, btw, are being used to bolster the claim that
Shakti Stones might work, over on audioasylum, in the
Randi threads.

The elephant they're trying to hide in plain view is this: So a big
slab of apparently solid material placed directly on the radiating
antenna attenuates the signal. This is supposed to be a surprising and
significant result why, exactly? It is not exactly an unknown
phenomenon that solid matter blocks radio frequency EM radiation better
than air. Where are the comparisons to other materials and especially
other shapes? I'd like to see a comparison to, say, a simple Faraday
cage made of ordinary sheet steel or aluminum. (More on that below.)

A quick & easy attenuation demonstration you can perform with no
expensive equipment: Take a cellphone with an external antenna,
preferably the extendable type. With the antenna extended, note how
many bars the signal strength meter is at. Now, without changing the
position or orientation of the phone (either of which can change signal
strength all by itself -- you only want to test one variable), close the
fingers of one hand around the antenna so that it is surrounded on all
sides. In most cases you'll lose at least one bar on the signal
strength meter, if not more. (Be sure to give it some time to settle
for both readings; I just did this with my phone and the meter has a
multi-second lag time.)

For a cruder demonstration, just walk inside a cave.


I mentioned Faraday cages above. These are nothing more than conductive
enclosures around an EMI source which cover it on all sides. A Faraday
cage must have no openings larger than the minimum wavelength the cage
is expected to contain. Holes smaller than that do not significantly
affect how much radiation escapes.

Faraday cages are by far the most common method for reducing EMI in
consumer electronics, since you get one for free if you build your
product's enclosure out of metal. For a great example of how much you
can puncture a Faraday cage without reducing its effectiveness, take a
look at Apple's PowerMac G5.


This brings me to the next elephant Shakti doesn't want you to notice.
The major issue in designing an enclosure to contain EMI (or prevent its
entry) is simply avoidance of holes or slits larger than the critical
length. Problems typically arise wherever the enclosure is punctured
for connectors, user controls, and so forth, because many of these items
are large enough to form exit/entry paths.

The theme you should be getting here is that EMI problems require fully
enclosing a device and paying attention to all possible paths in and
out. But the Shakti Stone is just a slab or bar which cannot possibly
fully enclose anything! For all I know it may do an excellent job
blocking what heads in its direction, but it does absolutely nothing for
any other path.

It's like saying that if you put a 3x3 inch square of cardboard next to
a naked 100 watt bulb, you've successfully blacked out that light.
Well, no, you haven't. You've blocked some paths for light to leave the
bulb, but plenty of light will radiate out all the other angles that are
still open. Even objects in the cardboard's shadow will typically
receive some light that originated at the bulb, due to diffuse
reflections off other surfaces and so forth.

And that analogy isn't actually an analogy! Light and RF EMI are both
examples of electromagnetic radiation. The principles are the same in
both cases; the main difference is that visible light is at much higher
frequencies (shorter wavelengths) than RF EMI.


Please feel free to repost this on audioasylum if you like.

--
Tim

In article , Timothy A. Seufert
wrote:

The elephant they're trying to hide in plain view is this: So a big
slab of apparently solid material placed directly on the radiating
antenna attenuates the signal. This is supposed to be a surprising and
significant result why, exactly? It is not exactly an unknown
phenomenon that solid matter blocks radio frequency EM radiation better
than air. Where are the comparisons to other materials and especially
other shapes? I'd like to see a comparison to, say, a simple Faraday
cage made of ordinary sheet steel or aluminum. (More on that below.)

In fact, the "stone" probably didn't attenuate the signal at all. The
most likely thing to have happened is that it changed the impedance of
the antenna. This would have increased the VSWR so that less energy got
to the antenna to be radiated. To any engineer at all familiar with EM
and especially with EMI the idea that placing a material in proximity
to a piece of electronics will significantly and reliably change the
EMI environment is laughable. You might as well chant "EMI go away"
while dancing naked.

Marc Foster
(Designing and analyzing antennas since 1979)

On 11/29/04 11:44 PM, in article , "Marc
Foster" wrote:

In fact, the "stone" probably didn't attenuate the signal at all. The
most likely thing to have happened is that it changed the impedance of
the antenna. This would have increased the VSWR so that less energy got
to the antenna to be radiated. To any engineer at all familiar with EM
and especially with EMI the idea that placing a material in proximity
to a piece of electronics will significantly and reliably change the
EMI environment is laughable. You might as well chant "EMI go away"
while dancing naked.

And if you are going to do that - please warn us all so we can be elsewhere
during that episode. ..


Marc Foster
(Designing and analyzing antennas since 1979)

On 29 Nov 2004 04:16:26 GMT, Steven Sullivan wrote:

Since I can't make heads or tails
of the graphs as presented (to answer even
simple stuff like, how big is the measured effect?),
I'm curious to hear the opinions of those who can.

I can. The graphs show clearly that with the shakti stones applied on
or near the device under test, or in the same room as the device under
test, the curves are lower than without. So we have, eh, lower MHz
noise floors. And, if you have looked further on, your car will run
faster, or better, as much as 6 mph.

The next huge improvement will be reached when you place a shakti
stone on your head. As you will know the brain produces a lot of
electric noise, which causes all kinds of stray fields and
uncontrollable electromagnetic eddies in and around your head. Wearing
a shakti stone in a hat on your head, will concentrate and absorb
those eddies into the stone, where this spurious energy will be
transformed into heat (a nice side effect during the dark and cold
winter days), leading to less distortions in the brain and hence to
CLEARER THINKING. Also recurring bouts of winter depression will be
alleviated.

Ernesto.

"You don't have to learn science if you don't feel
like it. So you can forget the whole business if
it is too much mental strain, which it usually is."

Richard Feynman

On 12/12/04 11:22 AM, in article , "Ernst
Raedecker" wrote:

On 29 Nov 2004 04:16:26 GMT, Steven Sullivan wrote:

Since I can't make heads or tails
of the graphs as presented (to answer even
simple stuff like, how big is the measured effect?),
I'm curious to hear the opinions of those who can.

I can. The graphs show clearly that with the shakti stones applied on
or near the device under test, or in the same room as the device under
test, the curves are lower than without. So we have, eh, lower MHz
noise floors. And, if you have looked further on, your car will run
faster, or better, as much as 6 mph.

The next huge improvement will be reached when you place a shakti
stone on your head. As you will know the brain produces a lot of
electric noise, which causes all kinds of stray fields and
uncontrollable electromagnetic eddies in and around your head. Wearing
a shakti stone in a hat on your head, will concentrate and absorb
those eddies into the stone, where this spurious energy will be
transformed into heat (a nice side effect during the dark and cold
winter days), leading to less distortions in the brain and hence to
CLEARER THINKING. Also recurring bouts of winter depression will be
alleviated.

While a Shatki stone won't do much of anything to a human, I don't think,
you might want to Google "Transcranial Magnetic Stimulation" for a laugh.

Out of the mouth of babes ... LOL