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mechanical resonance in MMs
mechanical resonance in MMs
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Old 22nd July 2017, 02:34 PM   #1401
Hiten is offline Hiten  India
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Thanks LD.
I don't understand figures but I trust your evaluation and verdict.

And also that of J. Walton because after so much elaborate painstaking study no reason to use different pictures in the book. He has written articles in Wireless World and authored a book (Probably many books). He must be highly reputed. And besides there is no valid reason.
Little confusing and intriguing.
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Old 22nd July 2017, 06:40 PM   #1402
Pano is online now Pano  United States
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mechanical resonance in MMs
The old SEM remains a mystery. Like you, I can't get it to fit the Decca test record.
But we should move past it, leave it to history. We need to do our own tests with recordings and micro photographs.

We should find someone capable of making clear micro photographs with a FOV ranging from 100-400 microns. 100μ would be a nice close up, 400μ could show 3 or 4 grooves, which might be useful. The test LP should be new, and photographed before any play. More photos should be taken, and recording done, after 1 play, 5 plays, 10, 50, 100. Or whatever intervals we deem relevant.

Since in our recording we have not seen horrible wear after 100 or more plays, it would be nice to photographically document that, as well as record and analyze it. That could be a big help for vinyl loves.

I can volunteer to abuse a test LP with a vintage EV ceramic cart and heavy tone arm.
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Old 22nd July 2017, 10:35 PM   #1403
billshurv is offline billshurv  United Kingdom
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mechanical resonance in MMs
I've asked someone who is doing some pretty trick stuff with optical if he can try. I think he is up for the challenge. Problem is, once we understand if the optics are up to it is making something that will take a 12" record without it needing to be sliced up.

Once place I haven't checked is lathetrolls. As most lathes have a microscope on them there must be some pics to show the resolution there taken with modern digital cameras.
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Old 22nd July 2017, 10:45 PM   #1404
Pano is online now Pano  United States
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mechanical resonance in MMs
Good thought!

Yes, I've been wondering how to support the 12" disk while under the microscope. And how to get the same area under the scope each time. Perhaps a template.
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Old Yesterday, 05:00 AM   #1405
Hiten is offline Hiten  India
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Record label can be marked with pencil for specific location on groove tangentially and specific frequency band can be played repeatedly. Since test record will be sacrificed repeated chance will not be there to test multiple time. What would be the ideal criteria for test ? From the book vertical tracking force, stylus mass looks like the main component. Any other ? Typical playing specs. at home of popular cartridge and tonearm will be good ? Higher frequency band will be more appropriate as amplitude on groove will be higher so even minor damage can stand out.
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Old Yesterday, 07:51 AM   #1406
luckythedog is offline luckythedog  United Kingdom
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Quote:
Originally Posted by Hiten View Post
..... also that of J. Walton because after so much elaborate painstaking study no reason to use different pictures in the book. He has written articles in Wireless World and authored a book (Probably many books). He must be highly reputed. And besides there is no valid reason.
Little confusing and intriguing.
Well, it's not about reputation, which is undoubted - rather about scrutiny and validity of detail concerning a pivotal point of principle that might well have influenced decades of beliefs and behaviours for the industry and consumers alike.

Set out on this thread is how one might challenge both theory and evidence, and point out fundamental contradictions, on the face of it.

Philosophically, I suspect much of the writing of the relatively few protagonists of the time who published publically in JAES, WW etc is/was treated as beyond challenge. Though some people at the time plainly did, because of published errata and letters etc. I think the skills needed to critique and form one's own opinion are within the grasp of many people these days, especially on forums as well skilled as this.

Personally, I don't like sitting on fences or tolerating loose ends in such things. When pivotal principles or axioms apparently don't stand scrutiny, one should call them out and discuss to a resolution - not least because that's an interesting and constructive thing to do, IMO.

If it looks like a duck and quacks, it's probably a duck. So if such things appear incomplete, contradicted by theory, and supporting evidence doesn't stand scrutiny, such things are probably wrong, IMO. Technical matters which are true stand scrutiny, and lack contradictions.

Anyways, I shall get off my soapbox now, or take it to speaker's corner - it is Sunday after all..............

LD

Last edited by luckythedog; Yesterday at 08:02 AM.
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Old Yesterday, 01:00 PM   #1407
Hiten is offline Hiten  India
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I think this may be the clue/answer. I found J. Walton article in 1963's April wireless world magazine. He has mentioned that SEM micrographs are flattened. It was also mentioned in Book scans Bill posted. Probably what he meant from flattened is that they are stretched vertically. Since SEM pictures are viewed from above the vinyl surface and groove walls being 45 degree the plane would have been seen at inclination. To compensate for that the pictures are stretched to see better details. In the link below we can see in page 172 of magazine (22 of pdf file) where actual real small image is at bottom and top one is stretched. Incidentally this later article mentions wearing of groove walls on first play it self and after 5 plays.
http://www.americanradiohistory.com/...ld-1963-04.pdf


I know I am bothering you too much LD. Please do enjoy music. Have a good day.
I presume most of your listening will be on vinyl. I mostly listen to vinyls as music I listen to dont have quality digital audio CDs.
Regards.
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Old Yesterday, 05:54 PM   #1408
Pano is online now Pano  United States
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mechanical resonance in MMs
Hiten, thanks so much for the WW link. There is good info and some idea of scale there, which is a big help. Reading it now.

For our own tests, I'd say for them to be taken seriously we'd have to use well known good carts and arms, starting with MM carts. Shure, AT or Ortofon carts could be used. Nothing exotic, just high quality carts and arms that typical enthusiasts would use. As I said earlier, I can supply the torture tests with vintage 1960s ceramic carts, or new ones. Showing the differences in damage will make the test all that much more convincing.
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