Vinyl & needle magnified 1000x

Yes, but the needle doesn´t have to fit more than a tiny amplitude normally. Therefore it can trace much higher frequencies, as the level is very low.

 

Thanks missan, that's how I understood it.

 

Yes, as you say it's like missan says - wavelength doesn't strictly come into it, just curvature which can be much bigger than any profile stylus radius in practice when level is low, even at high frequencies.

BTW, Quadjoe's posted stylus/groove image on the previous page looks a bit odd to me - where are the adjacent grooves, plus angles and curves look very aggressive in the groove I think......?

 

To clarify in the post above, 'big curvature' I mean 'having a big radius of curvature' ie be a shallow curve - sorry for confusion, but hope you get my drift. Groove curves can be shallow even for high frequencies at low levels. Natural levels of high frequencies are low for real programme material, and even RIAA comp doesn't fully use this up. For real styli in real programme material it can get close IME, sometimes limiting at high levels I think on extreme material, but by then g forces are also close to being limiting too........ the whole package of dimensions, g forces, RIAA, stylus shapes, mastering seems to have been cleverly devised to work, though there's plenty of pushing the envelope in practice to the point it sometimes doesn't IME.

 

Look at the scratch lower LH across 6 spirals and the debris and remember Alan Dower Blumlein invented the 45 degree stereo cutter head and amps in 1934 and EMI felt there was no commercial demand for it.

 

Yeah, I have a little peek, as well. Amazing what a minute diamond piece, wire etc etc can do.

 

Maybe, it could just be a trick of the perspective of the shot and how the image was cropped for presentation. Since I didn't take the image (as much as I'd love to have an electron microscope) I can't speak to that. I didn't even offer it up as any kind of definitive evidence, I just stated that I liked it. I will say that that shot is probably of a conical stylus since it's riding pretty high in the groove.

Here's another image not showing the adjacent grooves, sans a stylus tip. It's really a function of the enlargement of the image, and how the photo was cropped.

 

I'd have thought the groove walls somewhat smoother.

 

At that level of magnification, every imperfection in the surface shows up. Also, in order to prepare a sample for the electron microscope a lot of things have to be done. Here's a link that explains it:

http://sciencelearn.org.nz/Contexts...Preparing-samples-for-the-electron-microscope

In the case of the vinyl groove, you're actually looking at a gold or gold-palladium sputtered surface, since it gets hot in an electron microscope (150° C) the vinyl itself would deform.

 

they are but when you get to really high magnifications a "few thousand atoms here and there can make it look like the rocky mountain", the fact that a format that depents on direct contact of two surfaces can get 50 db +/- of signal to noise ratio is trully remarcable.
one trick the engineers apply to make a very smooth groove and obtain lower noise floor is to heat the cutting stylus, keeping the master lacquer warm also helps.
here's a cutting stylus you can clearly see the heater wire glued to it:

 

Hi Gregg

I think it would be cheating, as you suspected. 'Vibration' implies back-and-forth movement. Once you get to the highest frequency the stylus can trace I think you should call this the smallest vibration the stylus can track. If you take just a portion of the squiggle, you might get a deflection that is smaller than the wavelength of light, but you're not including a full back-and-forth movement so I wouldn't call that a vibration. Now, by looking at a portion of the vibration, you can get a deflection that it smaller than the wavelength of light, but if you think about it this applies to any movement at any scale. (I'm ignoring quantum mechanics here.) When you flip a coin, and the coin spins in mid-air, if you took a sufficiently tiny portion of the movement, you'd be looking at a scale that is smaller than the wavelength of light.

 

Very nice! Never been that close to a cutter head.

 

I believe those images represent what is typically there. Grain, texture and voids on this scale are a feature of real grooves that might go some way to illustrate the cause/role of friction. I'm sure it varies between records. It's amazing that vinyl can ever be as smooth as it is on this scale IMO.

 

Yes, I gave up on this idea. It would be cheating to break up the analog wave into small sections just to get close to the wavelength of light.

Basically it gets down to the fundamental difference between analog and digital. Analog is a wave. It can't be broken up into discrete, small packets. It is continuous. You have to accept analog on that basis. It is a whole. Digital, on the other hand, consists small samples which, when added together, make up the music. Digital is inherently pieces, not a whole.

Or to make it really simple, there is a difference between a cake and a piece of cake. Eight pieces of cake (or more) will make up a cake but nobody says, "I need a eight pieces of cake to feed the birthday party." Instead, we say, "I need a cake for a birthday party." Analog is like cake, and I like cake.

 

Just remember, that when you're listening to a digital source, you're not actually hearing the digital bits. Instead, you're hearing the reconstructed wave from the DAC. How well the DAC does it's job is really the issue between digital and analog. The higher the sampling rate, the more accurately the wave can be constructed, which is why SACD can sound so much better than a CD, all things being equal.

 

Yeah, I think it's comical when some people say they can hear the "stairsteps" of digital when that is, of course, nonsense.

Doug

 

Indeed ... and even if you actually wanted to reproduce the steps, it would be impossible. A speaker doesn't move in discrete steps, and sound doesn't propagate through air that way.

 

If you were somehow able to play a digital source directly without running it through a DAC (either its internal one or an external one) I suspect all you'd hear would be white noise of some sort, if anything. Now, I'm not saying that digital doesn't sound different than analog, but a well mastered CD or SACD played by good quality hardware can certainly approach or even surpass an analog source. Since we're getting off-topic here, and I don't want to derail the thread with the usual digital vs. analog debate, I won't add any further comments about it.

 

Depends on how well the DAC tracks the tiny grooves between the stairsteps.

 

Oops . . . selected the wrong quote. The only thing possibly worse than fumbling a punch line is fumbling the setup. So, one more time . . .

Depends on how well the DAC tracks the tiny grooves between the stairsteps.

 

Perhaps I didn't explain myself very well. There is no evidence that there is more high frequency information in the OP's image. My point about perspective is easily demonstrated by scaling and foreshortening my image so that it is on the same scale as the OP's image, and has similar groove curvature, thus:



As you can see, in my modified image, my picture seems to contain similar frequency information once you foreshorten it in the way that the OP's picture is foreshortened. Compressing the time axis of my image to match the OP's image produces similarly energetic grooves. The OP's picture dramatically over-emphasizes the apparent roughness of the groove by massively compressing the longitudinal perspective.

My point is that if the OP's image had been taken from directly above the groove instead of looking along it, we would be amazed by how smooth the groove is, and people would be saying there isn't much high frequency information there.

 

All makes you wonder how this got invented first.

 

Now ¨surface noise¨has a whole new meaning to me.

 

Of course, when this was invented, it was done on a much more "macro" level. Somebody just thought that if you vibrated some kind of cutter and cut some kind of material with it and then later used a stylus in the same groove that was cut and amplified it somehow, you would hear the same sounds as were engraved in the material.

It didn't take microscopics to imagine it would work.

Doug

 

St

Still pretty amazing technology for the time, and even today its much more fascinating and more of technological achievement than digital to me. Yeah, 1's and 0's I.C's ....digital can be made to do anything.