Macro Photos of Record Grooves

[ray_parkhurst]

I've started shooting record grooves using the same macro system I use for phono styli. My goal is to be able to identify wear in the grooves, and why it is happening. I'm planning to start with imaging a few records to develop a database, running it by the folks here and in other forums to gather feedback, and using the technique to evaluate record wear for some ongoing experiments.

Here are a few images I've taken recently:

3D image of an outer groove:

3D image of an inner groove, showing a possible wear patch of damaged/melted vinyl:

 

[Tom C]

Startling detail and clarity!

 

[solderdude]

Very nice pics !

The 2nd pic is not wear for certain but seems to be something happened in the pressing process since it is also seen in the bottom of the groove.
A needle, not even a Shibata, will go that deep in the groove. If anything, when it were wear, there would be some 'smoothing' seen in the middle of the groove at that point.

 

[My adventures in stereo]

Nothing romantic about these record photos, interesting project

 

[antcollinet]

Amazing! How on earth are you shooting that? It looks like you've created a 3d model of the surface.

 

[antcollinet]

Very nice pics !

The 2nd pic is not wear for certain but seems to be something happened in the pressing process since it is also seen in the bottom of the groove.
A needle, not even a Shibata, will go that deep in the groove. If anything, when it were wear, there would be some 'smoothing' seen in the middle of the groove at that point.

I'd agree with a pressing flaw. Plus it is very difficult to think of a way damage looking like that could be so localised - especially from heating.

 

[GXAlan]

Keyence scanner or DIY photogrammetry?

 

[Soandso]

As a curiosity here's how a tiny segment (1 mm square) of a musically recorded vintage wax cylinder. The color coded legend "u" like sign stands for micro; so the color legend is graduations of micrometers. [The highest surface ridge is 18.8 micrometers (for orientation the average human eyebrow hair micrometer diameter is about 2.5 times that).] Image as per Fedeyev, et al (2005) Journal of Audio Engineering Society 53(6):485-508.

 

[ray_parkhurst]

I called this "wear" since it only occurs on the leading edges of amplitude peaks. Not sure why a pressing flaw would only happen there, but I am not sure. This was the worst patch I found, and it does go to the bottom of the groove, but many other smaller ones are more localized. Here's a 2D view of another section showing several of these in a row, all on leading edges:

 

[Thomas_A]

I've started shooting record grooves using the same macro system I use for phono styli. My goal is to be able to identify wear in the grooves, and why it is happening. I'm planning to start with imaging a few records to develop a database, running it by the folks here and in other forums to gather feedback, and using the technique to evaluate record wear for some ongoing experiments.

Here are a few images I've taken recently:

3D image of an outer groove:
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3D image of an inner groove, showing a possible wear patch of damaged/melted vinyl:

View attachment 287786

Interesting part is the chopping patter on the upper part of the grove and the pattern all along down to the bottom. It does not look like a result from a typical contact patch of a stylus; damage seems too "broad". Is this a bad cutter stulys?

 

[ray_parkhurst]

Yes, that chop/chatter is very odd.

I need to look at more records with the same technique to develop a database as I've done with styli, but I'm not happy about having to cut them up, so I am thinking of building a system to allow me to view the whole record. This will allow me to shoot before and after play as well. It is not a trivial matter to shoot really tiny areas of large objects.

 

[Soandso]

If interested here's a high resolution photographic image for an idea about some of the vinyl depth patterns a master disc could impart. (Picture is part of a master disc working surface and is not a record surface groove as seen from above.) This is for a 331/3 r.p.m. record and unmagnified it is probably 45 micrometers wide (sorry, but am not absolutely sure of image magnification).

 

[Soandso]

If ever wondered what the actual pathways of stylus tracking looks like seen from above here is an example composite from a 3D confocal microscope that captured 180 surface points every time optical scanning was achieved. The green lines are the tracks through a portion of grooves from a 78 r.p.m. vinyl record. As per: Ballestraz & Seydoux (2009) "Estimation of groove position and correction of defects".

 

[Zapper]

I called this "wear" since it only occurs on the leading edges of amplitude peaks. Not sure why a pressing flaw would only happen there, but I am not sure. This was the worst patch I found, and it does go to the bottom of the groove, but many other smaller ones are more localized. Here's a 2D view of another section showing several of these in a row, all on leading edges:

View attachment 287912

It makes sense that those are wear points since they occur where the slope* is greatest, hence the force on the stylus is greatest. The large amplitude high frequency signal causing the wear is primarily in one channel. I don't think it is surprising that the wear extends almost to the bottom, because the sidewall of the groove is not rigid. The vinyl deforms significantly under the pressure from the stylus, and therefore the contact patch widens significantly, the same way the contact patch of a tire on the road widens due to the deformation of the tire. The deformation increases where the acceleration of the stylus is greatest. So one would expect these wear areas to show extended vertical contact between stylus and vinyl, even with a conical or elliptical stylus.

*More precisely, the force on the sidewall would be greatest where the positive derivative of the slope is greatest, IF the sidewall were rigid. That would be the point where the acceleration of the stylus is greatest, which is actually where the slope is zero for a sinusoidal signal. However, the vinyl sidewall is not rigid and undergoes compression. This causes the point of greatest pressure to lag behind the point where the positive derivative of the slope is greatest, and the point of maximum pressure moves from the point of zero slope towards the point of maximum slope.

 

[ray_parkhurst]

I have built a new system for imaging record grooves. I combined two system concepts into one, and improved rigidity same time...

First, here's the KR26B two-carriage rail that allows focus stacking capability:

I mounted the KR26B on a large 2-column copy stand like this one to allow imaging of larger objects:

I am now able to image any part of a record without having to cut it up, so I can study record wear with before/after images at any test point.

Now I need to identify a first candidate for a small study. Ideally I'd use a record with high HF levels on the innermost grooves. Any suggestions?

 

[Thomas_A]

Abba - Voleuz Vous - song The king has lost his crowns. I have not really heard a clean LP copy yet of the Abba ”choir”. Damage or just to high HF levels?

 

[Soandso]

Scanning electron microscope images of record groove segment(s) with respective scale bar(s): as per C. Supranowitz, Institute Optics University of Rochester OPT 307;

 

[ray_parkhurst]

Abba is a good choice. Indeed their albums seem to have very high HF content. I'm not sure I have a new copy of any of their albums though.

 

[ray_parkhurst]

Here are the first images with the new system. Arrival, last song on side 2 of Abba's Arrival album. Has good HF content. You can see the first quiet groove on the bottom in 2D, on left in 3D images.

I'm seeing the same type of "damage" as I saw on the previous album. I bought this album new back in 1978, and I am the only one who has played, it, but it has been played on a bunch of different systems with dubious stylus qualities. The first album I showed with this "damage" was purchased as NM from a record store about 2 weeks ago, so this is not an isolated phenom.

 

[MCH]

Here are the first images with the new system. Arrival, last song on side 2 of Abba's Arrival album. Has good HF content. You can see the first quiet groove on the bottom in 2D, on left in 3D images.

I'm seeing the same type of "damage" as I saw on the previous album. I bought this album new back in 1978, and I am the only one who has played, it, but it has been played on a bunch of different systems with dubious stylus qualities. The first album I showed with this "damage" was purchased as NM from a record store about 2 weeks ago, so this is not an isolated phenom.

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if you refer to the less dark areas in the grooves, they look like wear, but i wonder if they could be dirt or even some lubricants or plasticizers blooming out of the pvc. Have you tried washing one with a bit of soap and retaking the pics?
thanks for posting.