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Elliptical?

the thin end of the wedge

Re: Elliptical?

Postby phivates » 05 May 2012 01:50

Looks oval to me, unless the polishing is miraculous. Love tech-speak.
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Re: Elliptical?

Postby Ldg » 05 May 2012 13:28

Hepokatti wrote:Thank you ld. Now it makes more sense :)

EDIT: Might vinyl deformation play some part in where typical elliptical shape could offer advantages pushing the deformed vinyl away differently? Or is the deformation even that big considering modern, rather low stylus pressures?

You're welcome, Hepokatti.

As to vinyl deformation, my opinion is that it does not happen. At least to any significant extent as to affect contact mechanics and radii. But there's a plentiful body of opinion that it does.

If many ellipticals typically actually have the same curvature as sphericals, indentation would be the same irrespective of whether it's zero or some actual number. So it's sort of academic to the main point of this thread, of course.

One of the contradictions to indentation happening, IMO, follows on from consideration of what happens in styli with long contact lengths (major radius), or reduced minor radius. Both drag and indentation would increase, versus sphericals, if typical claimed contact region profiles are true. But friction/drag does not increase.
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Re: Elliptical?

Postby Hepokatti » 05 May 2012 21:52

ld wrote:One of the contradictions to indentation happening, IMO, follows on from consideration of what happens in styli with long contact lengths (major radius), or reduced minor radius. Both drag and indentation would increase, versus sphericals, if typical claimed contact region profiles are true. But friction/drag does not increase.


Sounds valid. In another forum there was a point thrown in the air that what if the groove's modulations come in such "density" on some records that the front/back cut would have an effect. The modulations in this case would be lifting the spherical stylus before it could establish it's full contact point in that said area. If you catch my drift? Sorry I can't explain it any clearer, as the original post is in different language posted by another person.

I think it might be possible, but I honestly don't know if modulations can be so dense for it to happen. I've seen some microscopic pictures of typical record grooves, but I've not seen modulations of such magnitude that could cause the mentioned effect in spherical stylus but not in elliptical. The whole issue is pretty difficult to perceive from photos, as I simply don't have the knowledge to know what to look for and how to look at it. Furthermore, the scale is rather deceiving!
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