Zany measurements and theories


I have to say that I do accept stylus drag exists, however where on earth do people get:
1. Stylus getting to temperatures that can melt vinyl - if so we'd never play out records more than once
2. Our records get hit with tons of pressure - if so why are none of my records smashed
parrotbee
"I only say this because I find it sometimes hard ti understand things without a comparative example"

Why a comparative example? If we are talking about a record melting, why not just get an actual example?

"01-23-15: Theo
I remember reading years ago, that because of the heat generated and vibration created as a stylus tracks a groove.
That you should only play that LP once in a 24 hour period to allow it to "rest" from the heat and vibration. Now that seemed pretty far fetched to me that a hard vinyl groove would actually vibrate. But on some microscopic level maybe it does?"

Compared to the stylus, the vinyl that a record is made out of is very soft. If something is going to give due to hardness, it won't be the needle. Also, a phono cart works off of vibration. There has to be some transfer back to the record itself.

More important, though, I promised the OP that I would find him some info on the subject. Your post triggered my memory as to where I read it first. I remembered it was years ago too, in a book called Good Sound by Laura Dearborn. Either late 80's or early 90's. I don't have the book anymore, but I'm pretty sure a lot of people posting here on Audiogon here still do. People reference it all the time. So if anyone that has the book can look the info up to confirm that the vinyl melts when played.

I also read it in another publication. I'm pretty sure it was in the Audio Perfectionist Journal. The article was an interview with Brooks Berdan. He's famous for turntable setup and repair. Unfortunately, I don't have that article either, and I doubt anyone else will either. APJ was pretty rare.

One last thing in response to the OP. I don't think the issue of melting was put into proper perspective. There's no question that there is a lot of heat generated when the needle passes through the record groove. But when some of us says it melts the record, that doesn't mean it liquefies the vinyl. It gets heated up to where it becomes softer. If you play the same record again, without letting it cool, it wares the record out faster, but it still plays and probably sounds the same. Its the kind of thing that builds up over time from abuse. Also, keep in mind that most audiophiles use higher end phono carts that have styluses cut to better conform to the record groove. They dig deeper into the record than a regular consumer grade needle. That combined with the fact that audiophile gear is much more revealing of flaws than standard gear, easily explains why we may pick out such differences, where many others can't.
I suspect that the vinyl that deflects from friction heat returns quickly to its
original form and is back to room temp before the record is finished playing.

For all this talk about a 24-hour cooling off period, is there any resarch to
verify this--with electron micrographs and temperature measurents with a
cooling-off timetable? No? Then a dogma has once again risen out of worst-
case speculation of a theoretical scenario with no verification.
Pressure is force/unit of area. For a phono stylus the force is small but the contact area is very, very small. Result, high pressure.

For another example,consider ice skates. Ice occupies more volume that liquid water, hence high pressure lowers the melting point (Le Chatelier's principle). Since the contact area of the skate is small, the pressure is high. High enough to melt the ice temporarily and lubricate the skate.
"Then a dogma has once again risen out of worst-
case speculation of a theoretical scenario with no verification."

It's not speculation. The contact point does get very hot. I did list 2 publications in my last post that dealt with this topic.

If you want some type of scientific explanation, look at it this way: How could there not be heat generated when playing a record. There's friction. I has to heat up.
Most estimates for stylus surface temps range between 300-
500 degrees(F). The temperature of your record will be
at(or close to) room temperature, except at the point of
contact with the stylus. Much will depend on VTF and
RPM(higher numbers there=higher temps). You're only talking
about milliseconds of contact, between the sylus and any
given point in the groove. Maybe a few molecules of vinyl
will be heated and the surrounding vinyl acts as a
heatsink(ice skate example, on a much smaller scale). I've
got a number of test records, that I used in my shoppe, for
setting up turntables. They were, of necessity, played
multiple times, during a setup. They are still as pristine
in function & sound as when I purchased them. Even the very
high velocity, "Tracking Torture Test Tracks." My
favorite demo record tracks, were often played numerous
times, within a few minutes, to compare my various speaker
models to customers. That was in the 80's and I'm still
enjoying those vinyls, with no loss of presentation.