Here are images related to my analyis of the needle drop file related to the Furutech controversy
Image1 is the CEP statistics sheet for file 1 (before demagnetization and replay)
[attachment=5084:Image1.jpg]
Image2 is the CEP statistics sheet for file 1 (after demagnetization and replay)
[attachment=5085:Image2.jpg]
Image3 is the spectral content of both waves over their full duration, 20-22K
Upper set (green line) are "before", L and R
Lower set (red line) are "after" L and R
[attachment=5086:Image3.jpg]
Image4 is the spectral content of both waves over their full duration, 7K-22K
Upper set (green line) are "before", L and R
Lower set (red line) are "after" L and R
[attachment=5087:Image4.jpg]
Could you add a third run without further modification so that average deviation between takes can be determined?
Here are my plots.
First is a HF response comparison, 100hz-22khz, black = L+R, blue = L-R... IIRC this is with a 20ms block size, 75% overlap, Hamming window. This is the "after" sample divided by the "before" sample, aligned, resped, and resampled in audacity and foobar. Vertical axis is difference in response in dB. The overall jagginess of the plot at high frequencies is a general artifact of limitations of the analysis process - because the samples are not time locked except at the start and end, small wow/flutter deviations can cause a doublet-type response (peak followed by drop). Nevertheless it is interesting that the L-R response is a bit more jagged, the L+R response is slightly over the L-R response (by perhaps 0.05db) at high frequencies. The L-R rise at 100hz and the sharp cut around 21khz are probably analysis artifacts.
Second is a LF plot, 0-50hz, 14.44 second block, Blackman-Harris window, otherwise same options. Vertical axis again is response difference in dB. These differences are much more substantial, and there is a clear pattern of regularity in the peaks and valleys - most particularly in the L-R plot - suggesting a harmonic nature to the differences. And in fact, something
like this is the most probable thing we would be looking for when we are searching for numerical changes in a post-Furutech LP - a change in any kind of ferromagnetic field on the LP would be scanned off by the cartridge coils as a quasiperiodic signal with a period of 33rpm (0.5556hz), and it would most likely be predominantly vertical (L-R) in nature. However, I don't believe that is a valid explanation for this plot, for the following reasons:
- A suggessful "de"magnitization of the LP should consistently reduce picked-up content, effectively improving the SNR. But there are very substantial peaks in this response, and I do not believe there is strong enough bass content on the sample to simply state this is the "correct" signal no longer obscured by magnetic noise.
- There are other, far more plausible ways for this difference to be generated. Most importantly, mechanical variations in the record - small variations in the warp - could cause this exact behavior. This could be caused by anything from heating inside the Furutech unit, to heating caused by merely handling the outside of the record with one's hands, to slight elastic deformations caused by the record sagging under its own weight while it is being handled, to even random variations in the motion of the belt or the tonearm. It is not necessary to resort to a relatively implausible reason as demagnetization to explain this plot.
[attachment=5088:hfplot.png]
[attachment=5089:lfplot.png]
What about static electricity? Vinyl should be very susceptible to that and it might interact with the device's strong magnet field. To rule this out you could put a LP into a grounded bowl of distilled* water. That should remove all static charge as long as you let it dry off without wiping.
* to prevent limescale
The graphs suggest we needed at least a third file, of a record played after a sham Furutech 'demagnetization' (i.e., all handling the same, except no actual demag - maybe by not powering in the device?) , but before a 'real' demagnetization, to see how much variation can be expected as background.
Yeah, some repeat plays would be really beneficial, particularly to shore up the variability in the LF plots.
rpp3po, I had similar thoughts, but I'm not sure that it is all that important. The pickup is fundamentally inductive in nature, but I would imagine that the time-varying magnetic field generated by the time-varying electric field - ie, the second derivative of the electric field - is likely going to be pretty damn small. Besides, many vinyl formulations are antistatic to begin with (they are slightly conductive).
BTW, I attempted to measure the effects of record magnetism myself by performing a cepstrum on a recording of a Stanton V500 w/o stylus assembly hovering over the record surface, and comparing against when the record was absent. A 33rpm harmonic should be stronger in the former case, but once I aligned the position of the tonearm with accuracy, everything nulled out. I expect that this sort of scheme is considerably more sensitive than Fremer's recordings, because the mechanical component of the signal pickup is removed entirely.
What about static electricity? Vinyl should be very susceptible to that and it might interact with the device's strong magnet field. To rule this out you could put a LP into a grounded bowl of distilled* water. That should remove all static charge as long as you let it dry off without wiping.
* to prevent limescale
I hope that nobody reading this will actually try it. This sounds like a very bad idea.
There are products specifically made for cleaning vinyl records that probably work quite well. Let's stick to those.
What about static electricity? Vinyl should be very susceptible to that and it might interact with the device's strong magnet field. To rule this out you could put a LP into a grounded bowl of distilled* water. That should remove all static charge as long as you let it dry off without wiping.
* to prevent limescale
Static and electromagnetic fields don't interact directly. Technically, they are orthogonal to each other. They co-exist without interacting. Think about it - strong magnets don't collect or dissipate static electricity with their magnetic fields, and static fields don't increase or decrease the strength of magnets.
The "demagnetiser* itself might have some effect on a LP's electrostatic field by discharging it through conductive parts. But so would any number of other perfectly ordinary things.
The graphs suggest we needed at least a third file, of a record played after a sham Furutech 'demagnetization' (i.e., all handling the same, except no actual demag - maybe by not powering in the device?) , but before a 'real' demagnetization, to see how much variation can be expected as background.
Right, I mentioned this (yesterday?) on the SP forum. There needs to be a control procedure with the same steps and components, except no demagnetization.
Reading the SP forum is like watching a remake of "Dumb and Dumber". There are so many people there that obviously don't understand doing experiments at the level of even an average middle-school student.
I was reading a post by a guy who claimed to be some kind of an engineer, who apparently didn't think that there was such a thing as Teflon-insulated coax with the same impedance as the standard stuff.
The solution to Golden Earism is education *before* the idealogues take over.
This sounds like a very bad idea.
You can surely substantiate that claim, can you? Are you scared of things without shiny packaging?
There are products specifically made for cleaning vinyl records that probably work quite well. Let's stick to those.
You don't want two things to (only) rule out static electricity:
- Static electricity removed from the upper surface but not from the inner groves.
- Residues from a cleaning fluid, wether conductive or not.
Else you would either introduce new sources of error or not remove static influence completely.
Static and electromagnetic fields don't interact directly. Technically, they are orthogonal to each other. They co-exist without interacting.
The Furutech device produces a rapidly changing magnetic field, isn't that a different influence for a static field than that of a bar magnet?
This sounds like a very bad idea.
You can surely substantiate that claim, can you? Are you scared of things without shiny packaging?
Distilled water has a very high surface tension, and so extremely poor wetting characteristics. Any surface contaminents on the vinyl will probably redistribute themselves unevenly on the surface, causing potential problems.
Also, distilled water is a poor conductor of electricity, so if your goal is to remove static charge then this is not a good choice.
The Furutech device produces a rapidly changing magnetic field, isn't that a different influence for a static field than that of a bar magnet?
A magnetic field, no matter how fast it is changing, will have zero effect on a stationary static charge. Only a charge which is moving is affected by magnetic fields, and even then the effect is still weak.
Any surface contaminents on the vinyl will probably redistribute themselves unevenly on the surface, causing potential problems.
Very adventurous thesis.
Also, distilled water is a poor conductor of electricity, so if your goal is to remove static charge then this is not a good choice.
Autoprotolysis should make it sufficient for the relatively low amounts of charge that need to be moved.
A magnetic field, no matter how fast it is changing, will have zero effect on a stationary static charge. Only a charge which is moving is affected by magnetic fields, and even then the effect is still weak.
Since the earth is not the center of the universe there is no way to tell wether a charge is moving within a field or the field around the charge.
Also, distilled water is a poor conductor of electricity, so if your goal is to remove static charge then this is not a good choice.
Autoprotolysis should make it sufficient for the relatively low amounts of charge that need to be moved.
Distilled water will simply form an electrical double layer around the surface charge.
Any surface contaminents on the vinyl will probably redistribute themselves unevenly on the surface, causing potential problems.
Very adventurous thesis.
Hardly -
if there's any foreign matter on the vinyl, and
if it goes into the water, it's obvious that the water is going to trickle off the vinyl in some kind of pattern, dropping some of that foreign matter on the way.
Maybe you've never washed anything?
Cheers,
David.
Since the earth is not the center of the universe there is no way to tell wether a charge is moving within a field or the field around the charge.
Perhaps we should repeat the Millikan experiment, except this time when the oil drops are stationary in the electrical field, we apply a magnetic field. According to you, the drops should now begin to move again, and the speed and direction of their motion will tell us the speed and direction that we are traveling through space, in the absolute sense.
Since the earth is not the center of the universe there is no way to tell wether a charge is moving within a field or the field around the charge.
Perhaps we should repeat the Millikan experiment, except this time when the oil drops are stationary in the electrical field, we apply a magnetic field. According to you, the drops should now begin to move again, and the speed and direction of their motion will tell us the speed and direction that we are traveling through space, in the absolute sense.
You are turning around my point, which was exactly that there is neither absolute movement nor position in this universe, but only relative. The Milikan experiment employs a drop's mass in relation to the earth's mass to derive the charge of an electron. The fact, that the earth is involved in this experiment is just this specific experiment's property. I repeat: a charge moving within a field or a field moving around a charge are identical from the charge's point of view.
I guess I got sidetracked on the whole magnetic field issue. Sorry.
So what are we really talking about here? Is it that the permanent magnet in the cartridge exerts a force on the surface charge of the LP as it passes by? Or are we saying that the moving charge creates a varying magnetic field that the coils in the cartridge pick up as a signal?
rpp3po, I had similar thoughts, but I'm not sure that it is all that important. The pickup is fundamentally inductive in nature, but I would imagine that the time-varying magnetic field generated by the time-varying electric field - ie, the second derivative of the electric field - is likely going to be pretty damn small.
Couldn't it be that static electricity is unloading into the needle in very short bursts as the needle approaches it? This would cause slight mechanical vibration instead of direct magnetic inductance (as a derivative of the electric field) and could indeed modify the spectrum somewhat.
I stopped paying any attention to vinyl many years ago, but if I recall, there were devices that removed the static from the record as it was being played. I think one such device used radioactive polonium to do this. I'll bet those cost a lot less than the demagnetizer, plus there is no evidence that the demagnetizer even removes static.
I agree there would be far cheaper methods for static removal and it is not clear wether that esoteric device can remove static at all. I was just speculating about the possible causes IF there really was a measurable difference (we are still waiting for a 3rd control take). Magnetism can surely be ruled out for vinyl. The only two options I see remaining are thermal differences and static (or general climate if a lot of time passes between needle drops).
I think one such device used radioactive polonium to do this.
Now that really seems a little scary combined with the fundamentalistic mindset you can sometimes find among the anti digital movement!
I think one such device used radioactive polonium to do this.
Now that really seems a little scary combined with the fundamentalistic mindset you can sometimes find among the anti digital movement!
OT, but:
Staticmaster (and others) still available: http://www.2spi.com/catalog/photo/statmaster.shtml (http://www.2spi.com/catalog/photo/statmaster.shtml)
Polonium is only dangerous if ingested or inhaled. There's a discussion at, of course: http://en.wikipedia.org/wiki/Polonium (http://en.wikipedia.org/wiki/Polonium)
At the end, a claim that you'd need a lot of Staticmaster refills to do anything dangerous.
Here are images related to my analyis of the needle drop file related to the Furutech controversy
Where can these audio files be found (URL) ?
http://idisk.mac.com/musicangle-Public?view=web (http://idisk.mac.com/musicangle-Public?view=web)
First 2 files in the list.
Irrelevant to the thread, but a place to hang the attachment for reference elsewhere.
Domine pt2.wav - 16/44 choral segement
Static and electromagnetic fields don't interact directly. Technically, they are orthogonal to each other. They co-exist without interacting. Think about it - strong magnets don't collect or dissipate static electricity with their magnetic fields, and static fields don't increase or decrease the strength of magnets.
Sorry to butt into this older portion of the thread - Arny, I understand what you're saying but the terminology confused me momentarily. I think you're saying that static electric and magnetic fields don't interact directly, and that's true. When you say "electromagnetic", by definition you're talking about dynamic electric and magnetic fields which are orthogonal. What this means is that there is both a changing electric field AND a changing magnetic field present at the same place and time. And yes, a static field of either kind will have no effect on a static field of the opposite kind.
A magnetic field, no matter how fast it is changing, will have zero effect on a stationary static charge. Only a charge which is moving is affected by magnetic fields, and even then the effect is still weak.
Technically, you cannot have a dynamic magnetic field or electric field except in isolation. The moment you introduce a dielectric (such as "free space" or a conductor, a changing electric or magnetic field will induce the other, and you will see an electromagnetic field. Maxwell's 3rd and 4th laws. This is how radio works; a changing electric charge distribution in an antenna (conductor) causes electromagnetic waves to be generated at the aperture (free space). So in a real-world situation a changing magnetic field will generate a dynamic electric field, which in turn will affect that static charge - by causing it to oscillate. The reason a moving charge is affected by a magnetic field is that the charge's motion causes a magnetic field to be generated (right-hand rule) which will interact with other magnetic fields. This is how detectors work in particle accelerators, for example.
Sorry for the pedantry; it's not that I disagree with the positions being stated, it's just that my EE training pipes up from my hindbrain occasionally and demands to be let out. The relevancy is that any static charge on an LP will indeed generate a magnetic field as the LP spins, although at a low frequency as noted elsewhere in the thread. As Axon states, its effect on the cartridge is likely to be very very small.
End of sidetrack; please carry on, this is interesting.
Thanks for the link, Andy.
I have to admit having misread your graphs at first. I was under the impression that the diverging curves where showing before and after demagnetization response, but it turns out to be the L/R channels response, right ? Details are not easy to see in the jpg files.
When I analyze the audio files, the spectral difference between the two is very small, IME similar to subsequent playbacks of an analog master tape. Definitely not a significant difference.
What was your conclusion about the difference between the two files (apart from the obvious speed difference) ?
Thanks GregDunn, I like your explanation.
So, are you saying that in theory the moving charge on the surface of the vinyl will induce a magnetic field that will possibly create a force between the record and the permanent magnet of the cartridge, or will possibly induce a current in the cartridge's coil? I don't think we need to calculate how vanishingly small either of those would be, but it is interesting to theorize anyway.
The other possibility, that the charge on the vinyl could create a static force against the arm, should only be possible if the arm itself is charged, and the arm should be neutral. Might the needle, being diamond, pick up a static charge from friction with the vinyl, to interact with any charge on the vinyl?
Thanks for the link, Andy.
I have to admit having misread your graphs at first. I was under the impression that the diverging curves where showing before and after demagnetization response, but it turns out to be the L/R channels response, right ? Details are not easy to see in the jpg files.
When I analyze the audio files, the spectral difference between the two is very small, IME similar to subsequent playbacks of an analog master tape. Definitely not a significant difference.
What was your conclusion about the difference between the two files (apart from the obvious speed difference) ?
I concluded that the experiment was too badly done to reach any conclusions. They did not collect enough data. They never tried two sucessive playings of the LP *without* any demagnetization in-between.
Irrelevant to the thread, but a place to hang the attachment for reference elsewhere.
Domine pt2.wav - 16/44 choral segement
Since JA has made a big issue out of his X/Y graphic analysis of the previous recording, I've uploaded a version of it that looks great on a phase scope!
[attachment=5117:domine_pt2_phased.flac]
They never tried two sucessive playings of the LP *without* any demagnetization in-between.
Bingo. I'm confident that with the right source material any two consecutive plays of an LP, if removed from the platter and then randomly replaced back down on the platter, will be audibly distinguishable in rapid fire, needle drop [digitized recordings] ABX comparisons.
Although there are several causes, the most common form of audible wow in record playback is due to the imperfect centering of the spindle hole, placed in the record after the grooves are stamped in. This causes a wavering in the effective playback groove speed, hence pitch, per rotation. As a record spindle hole wears with repeated use over the years it widens. This allows the user to place the record down on the platter spindle and shove the record ever so slightly left/right/up/down to compensate for the original hole eccentricity. . . *or* to make audible differences in that subsequent playback by shoving the record in a different direction between plays, consciously or unconsciously, due to the change in higher and lower effective groove speed locations around the disc.