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Images related to the furutech controversy

Reply #25
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. 


Images related to the furutech controversy

Reply #26
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) ?

Images related to the furutech controversy

Reply #27
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?

Images related to the furutech controversy

Reply #28
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.

Images related to the furutech controversy

Reply #29
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]

Images related to the furutech controversy

Reply #30
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.

 
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