Stylus as a bobsleigh in orbit.......!?

[Ldg]

No worries, BK, sums are hard I find, maths is easy !

A corollary of the speed at which the groove wall flashes by on the scale of the stylus is that high speed photography wouldn't even capture it. If one could ever zoom in on the business end pointy bit so as to see the contact, the groove wall would just be a blur. If the contact region has an extent of a few um, it traverses about 150000x or so its own dimension each second.

No comments on the obvious similarity between the London Gherkin building and a fineline stylus.........!?

[Alec124c41]

Direct drive?

Cheers,
Alec

[Bran Kulez]

ld wrote:...C'mon, these things don't happen by chance, someone has found the instructions we sent into space on how to build a record player, and has just got the scale a bit wrong...

...assuming they have good music up there, this could be the next wave in high fidelity...and yet another classification of drive type...once they get the scale right...

[thommo_work]

"Guess I'm going to have to buy the White Album again"

[Ldg]

ld wrote:...C'mon, these things don't happen by chance, someone has found the instructions we sent into space on how to build a record player, and has just got the scale a bit wrong...

...assuming they have good music up there, this could be the next wave in high fidelity...and yet another classification of drive type...once they get the scale right...

That's funny !

[Squiffything]

I'm sorry but I didn't get the math/vinylengine babel fish either that or you lot have been on the 65 year old hippies magic mushrooms again I really need to have a word with him about them

[Ldg]

Well, no doubt there is a correct soundtrack to this thread. Personally, I think the very original mix of "Tomorrow Never Knows" which only made it to pressing on the 1st day of the mono mix would suit nicely

BUT...............the thread is not without point, IMO.

One of the crux questions in stylus-groove mechanics is 'does indentation happen ?'. And convention has it that intuitively the answer is yes. But I think this visualisation of how fast the stylus-groove interface changes alters that intuition. I venture it reverses it. So that it's intuitive it doesn't indent, rather it skids the surface ?!

[Bran Kulez]

Having to google "babel fish" may disqualify me for the 65 y.o. hippies on mushrooms club... ...but there's hope, getting "Tomorrow Never Knows" on vinyl is on my to-do list...

[missan]

Well, no doubt there is a correct soundtrack to this thread. Personally, I think the very original mix of "Tomorrow Never Knows" which only made it to pressing on the 1st day of the mono mix would suit nicely

BUT...............the thread is not without point, IMO.

One of the crux questions in stylus-groove mechanics is 'does indentation happen ?'. And convention has it that intuitively the answer is yes. But I think this visualisation of how fast the stylus-groove interface changes alters that intuition. I venture it reverses it. So that it's intuitive it doesn't indent, rather it skids the surface ?!

In this case my intuition has always been 'no indentation', but my intuition is not always right.
missan

[Hanuman]

One of the crux questions in stylus-groove mechanics is 'does indentation happen ?'. And convention has it that intuitively the answer is yes. But I think this visualisation of how fast the stylus-groove interface changes alters that intuition. I venture it reverses it. So that it's intuitive it doesn't indent, rather it skids the surface ?!

I'm not sure intuition cuts it here, either way. You wouldn't intuitively expect a solid enough object like a golf ball to do this either:

http://www.youtube.com/watch?v=aMqM13EUSKw

This clip illustrates, I think, the perils of hypothesing behaviour based on only what we can detect with our senses. Technology extends our vision, especially, in dramatic fashion. That golf ball would have just hit the plate with a thud and dropped to the ground, with the viewer none the wiser to the dramatic temporary change of form and maybe even of state. If I've calculated correctly that action took place over a time period of 2 milliseconds.

Yes, the record groove moves under the stylus at a relatively huge speed, in our terms, but that doesn't preclude the possibility of a lot of interesting and unexpected things going on that we have no idea about.

[Ldg]

Absolutely. I'm simply attempting to redress the balance of where intuition conventionally has led. I can readily use physics to show that the groove can't indent, for example, because of energy considerations, but not many people would get it (probably), and in any event if it's true it ought to pass the common sense test anyway !

But realising that groove-stylus mechanics is a very high speed affair helps intuition lead the right way, I think. And I don't think it is intuitive unless one considers what it would look like if one was able to ride on the stylus, and then it becomes so.

And the golf ball example is an excellent example of how things we consider rigid might not be when they move or are subject to extremes of jolt, or are considered on a very short timescale. Which also has very pertinent applications is vinyl replay. Cantilevers, for example, probably are pretty flexible tubes. And if we could see on a slow-mo timescale we'd probably see vibrations worming along what appears to be a flexible tube. Whereas conventional intuition has it that cantilever is rigid and moves as a body.

But the whole cantilever/cartridge/arm/pivot/armboard/plinth has potential to be wobbly when considered in slow-mo...........

I've seen film of jet engine rotor blade tests, simulating a bird strike at 250,000 frames per second. The rotor blades bent right back on themselves, and the gelatine test bird stayed intact for a short time. If you see one of these blades, they are so big and seem totally unbendable, it's incredible. In physics, it's perfectly explanable and is what is predicted. But adjusting intuition so that it matches what actually happens in such things is difficult in the absence of knowing how the high speed world operates.

[missan]

Intuitively I cannot see this happening with my golf bolls, wonder what kind of brand they used in this video.
missan