Striations along the groove wall

[statfi]

Left Chl Groove Wall (003).jpg, attached, is a photo of the left channel of a test record. Does anyone know why the striations running vertically in this view are there? Are they endemic to LPs in general? What do they sound like on playback?

[boogievan]

It reads 3710X magnification, so, it's zoomed in more than 3X what the lab's 1kX mic can do, and 24X what most lathe mics can do. Is it not just the nature of the cut which looks smooth at 150X, but at 3kX has signs of the rip and drag process done to the formula by the stylus during cutting and that faithfully being replicated in Nickel and then Vinylite?

Here are more photos of zoomed-way-in grooves: https://thevinylfactory.com/news/incredible-photos-of-record-grooves-under-an-electron-microscope/

Cool image of just one wall[y];

[statfi]

Nice SEM images! Can you tell me or point me to more about "the rip and drag process". It seems to me that this must not be endemic (as "stick-slip" is for violin playing) given the smoothness of the walls in the first image in your nice reference but does appear in the third and fifth images. Also the striations in the image I posted seem to be very long and continuous along the groove, as is the case in your reference's third and fifth images.

[boogievan]

Indeed, a stick-slip mode of 'cutting' taking place at the SEM level of magnification... - but with burnishing applied by the ultra-small side facets of the stylus that might result in these long striations that certainly are following the longitudinal motion of the land that passed under the (fixèd) stylus...

The first image at the link has both walls shown approximately to be within 50 µm (so, 25 µm per wall), whereas Wally's single wall takes up at least 33 µm, making the double-walled groove an equivalent 66 µm. What if the images at the link I shared just needed to be zoomed in a little bit more in order to reveal los striations? ...because, observe this more-zoomed-in SEM shot - with the single wall of the groove zoomed in to be about 40 µm that shows striations looking just like the Ortogrooves in Wally's mic, innit?

striations.jpeg

[abduction emoticon]

[Dub Bull]

These are images of played records, yes? If so, it's most likely that the striations are caused by pickup stylus edge-jaggedness (when the styli wore out). They were dragged through the groove and made those marks.

Check out the striations in the grooves that were damaged by worn styli of both the elliptical and Shibata types, about 75% down this page:

http://pspatialaudio.com/stylus_wear.htm

Ironically, the claim is that Shibata styli - although less damaging to the groove when new - cause even more damage when they chip - and they must chip, due to their tiny dimensions. smh

= [He] is risen, indeed!

[boogievan]

Agree. It's probably from playing back with worn styli. I've never seen striations at 150x, though, so, there's something to the idea of one needing to zoom way the Hell in before they're visible.