Pics of LP Record Grooves

[ray_parkhurst]

I've been shooting record grooves to monitor them for wear due to playing. My first attempts have required me to cut up the record since I don't have a big enough stage, with enough overhang, to shoot anywhere on the record. I'm planning to build a 2-column system for this purpose, but for now I'm shooting pieces to see how they will come out.

First attempts...50x Mitty BD...36 shot stack:

Overall 2D view:

Zoomed-in 3D view:

[Chris S.]

Very cool.

I'm surprised that the grooves, in cross section, appear to have structure that appears stratified. Are LP blanks built up in layers?

--Chris S.

[ray_parkhurst]

Very cool.

I'm surprised that the grooves, in cross section, appear to have structure that appears stratified. Are LP blanks built up in layers?

No, I believe they are made as single "blanks" before pressing. Those lines may be due to an earlier process such as cutting, plating, etc, or due to wear from one or more styli. I am not sure yet, as I've only done a couple records so far. I'm hoping to develop a database of images as I've done with phono styli to learn more about the various processes.

[blekenbleu]

I'm surprised that the grooves, in cross section, appear to have structure that appears stratified. Are LP blanks built up in layers?

According to "Handbook for Sound Engineers", LP vinyl grooves literally melt while styli are dragged thru them;
striations may be from debris that was dragged along with nominally polished diamond.

[ray_parkhurst]

I'm surprised that the grooves, in cross section, appear to have structure that appears stratified. Are LP blanks built up in layers?

According to "Handbook for Sound Engineers", LP vinyl grooves literally melt while styli are dragged thru them;
striations may be from debris that was dragged along with nominally polished diamond.

Yes, some have done calculations that theoretically point to the possibility of melting, though it has never been proven by anyone. I'd like to get some data to show if indeed this happens. Vinyl is fairly soft, even without plasticizers, so it will deform when the stylus rubs against it. Does that damage it? Melt it? Nobody knows for sure. Vinyl does give off gases when heated above a certain temp, but those gasses are at vanishingly small volumes so tough to detect. Once it outgasses, it becomes more brittle, so should change in either sound character (noisier?) or wear "differently" the next pass of the stylus. If I can image any part of a whole record, I can try some experiments to see what happens with playback by different stylus types, amount of wear, etc. Different stylus types, with different amounts of wear, hit the groove in different places, so that might be an explanation for the "layered" look to the grooves above. I think it will be interesting, though as some audio forum members have said, perhaps "30 years too late". But there is currently a vinyl resurgence, with records recently outselling CDs, so there are indeed a bunch of folks who are interested today.

[ray_parkhurst]

Very cool.

I'm surprised that the grooves, in cross section, appear to have structure that appears stratified. Are LP blanks built up in layers?

One more thing...the perspective image is not "real", just a 3D rendering of the data from the 2D. You can see this in the various distortions and such due to smoothing. It's not bad, but I do need to work on technique to help minimize smoothing required. It probably comes down more to lighting (as always) than step size, given good stability. The exposures are very long, so plenty of room for movement.

[Beatsy]

Very interesting topic and images.

Reminded me of a guy I saw interviewed on TV many years ago (maybe 50?). He could tell what tune was on a record just by looking at the grooves. Eyeballs only with no magnification. They presented him with a few random records, classical to (then) modern, with the labels covered up and he got every one right. Impressive musical knowledge too!

[Doppler9000]

There were a few attempts at commercializing optical turntables, using lasers as pick-ups.