Long long ago in a galaxy far far away I was employed at an Audio Engineering Department. Since at that time there was still a lot of money for these things, one of the then senior researchers had set up a small lab to do experiments on record playing.
One experiment was to determine the temperature of the stylus while a record was playing. I don't remember alle the details but one result I still know, on a 12" record playing at 33 1/3 rpm it was measured to go up to 70 degrees centigrade.
(Incidentally, this lab was set up on the first floor of an old villa which had a wooden floor and was situated about 300 meters from a railroad -- this was a constant source of humorous situations especially as the researcher in question was a bit short-tempered)
One experiment was to determine the temperature of the stylus while a record was playing. I don't remember alle the details but one result I still know, on a 12" record playing at 33 1/3 rpm it was measured to go up to 70 degrees centigrade.
(Incidentally, this lab was set up on the first floor of an old villa which had a wooden floor and was situated about 300 meters from a railroad -- this was a constant source of humorous situations especially as the researcher in question was a bit short-tempered)
Last edited:
Diamond has a thermal conductivity around 2000W/m/K, 5 times that of copper, meaning a stylus isn't going to drop more than 10 degrees C or so for a few mW of frictional heating, keeping the friction contact surface too cool for frictional melting. If you assume 2g tracking force of drag and 0.5m/s velocity, and 0.3 friction coefficient that's 3mW of frictional heating. If each contact zone is something like 3um by 10um, thats 100MW/m^2 (big) for about 6us (small), or about 600J/m^2 dumped into the friction interface - even if all of this heat went into the vinyl that's comparable to 1 second of sunlight in terms of area heating - trivial. And the contact pressures would be 100's of MPa (without deformation that increases contact area), clearly the physical properties are the issues for wear, not thermal issues.
We all knew this anyway really - leave a cholocate bar in your pocket once and its ruined, its not a gradual degradation over repeated episodes!
The pitting in the electron micrograph suggests a plucking action - if this is wet play then the solution used is doing most of the damage I suspect, as the tip passed over a point the solution will have high negative pressure in the wake and be able to exert high plucking forces. With air play the wake pressure is limited to a vacuum at worst. Liquids can also cavitate which would generate shock waves and significant damage like pitting. Actually a round object passing through a liquid can generate turbulent wake forces - the more I think about wet playing the more it seems a disaster for vinyl, aquaplaning, viscous friction, turbulence, plucking forces, cavitation, ...
If the pitting is due to dry play, its got to be simple force overload cracking the material, over time cracks meet and bits fall off - but this doesn't agree with other micrographs I've seen of worn vinyl really, which show striations along the groove.
We all knew this anyway really - leave a cholocate bar in your pocket once and its ruined, its not a gradual degradation over repeated episodes!
The pitting in the electron micrograph suggests a plucking action - if this is wet play then the solution used is doing most of the damage I suspect, as the tip passed over a point the solution will have high negative pressure in the wake and be able to exert high plucking forces. With air play the wake pressure is limited to a vacuum at worst. Liquids can also cavitate which would generate shock waves and significant damage like pitting. Actually a round object passing through a liquid can generate turbulent wake forces - the more I think about wet playing the more it seems a disaster for vinyl, aquaplaning, viscous friction, turbulence, plucking forces, cavitation, ...
If the pitting is due to dry play, its got to be simple force overload cracking the material, over time cracks meet and bits fall off - but this doesn't agree with other micrographs I've seen of worn vinyl really, which show striations along the groove.
Going back to the skating comparison, I've seen film of a weighted wire placed across a block of ice and the pressure of the wire caused the ice to 'melt' and then refreeze behind the wire with the effect that the wire passes through the block leaving it whole. It looks unbelievable, but. So I'm not discounting a similar effect on vinyl. But clearly that's not friction or temperature.
But I'm not convinced by the high tip temperature...
But I'm not convinced by the high tip temperature...
Probably this is the reason why records played wet with Lencoclean are scratchy and noisy when played dry afterwards.
The "melting under pressure" effect of skating is actually due to water having a lower density when frozen (the reason ice floats on water) -- you can "melt" ice by compressing it. This is rather unique to water, there are few substances that have the same properties. It is definitely not a thermal effect.
As for Lencoclean, I've always understood that there is a lot of grime at the bottom of the groove. When you play the record wet, you whirl all that up (the stylus doesn't reach all the way to the bottom) and you leave a somewhat sticky residue on the walls of the groove. Now when you play that same record dry again, all the stuff that didn't bother you before because the stylus rode over it, now is stuck to the walls of the groove where it DOES contact the stylus so you can now hear it.
As for wear, one of the things I learned was that for stylus pressure, do follow the recommendations but if you err, it is better to be too heavy than too light. The reason being, if your stylus pressure is too low, you may risk the stylus losing contact with the groove wall. If that happens, you enable the stylus to build up speed with respect to the groove wall so when it makes contact again, it is with enough force to chop off little bits. If your stylus pressure is "too high" indeed you have more friction, but that is negligable damage compared to the chop-off effect of a stylus that cannot maintain contact with the groove wall.
I've seen many microscope photographs of grooves, they are funny. Especially trumpets and so can make them do scary things.
As for Lencoclean, I've always understood that there is a lot of grime at the bottom of the groove. When you play the record wet, you whirl all that up (the stylus doesn't reach all the way to the bottom) and you leave a somewhat sticky residue on the walls of the groove. Now when you play that same record dry again, all the stuff that didn't bother you before because the stylus rode over it, now is stuck to the walls of the groove where it DOES contact the stylus so you can now hear it.
As for wear, one of the things I learned was that for stylus pressure, do follow the recommendations but if you err, it is better to be too heavy than too light. The reason being, if your stylus pressure is too low, you may risk the stylus losing contact with the groove wall. If that happens, you enable the stylus to build up speed with respect to the groove wall so when it makes contact again, it is with enough force to chop off little bits. If your stylus pressure is "too high" indeed you have more friction, but that is negligable damage compared to the chop-off effect of a stylus that cannot maintain contact with the groove wall.
I've seen many microscope photographs of grooves, they are funny. Especially trumpets and so can make them do scary things.
This proces called Regelation was discovered by Faraday some 200 years ago
https://en.m.wikipedia.org/wiki/Regelation
In this case the pressure exceeds the Yield point, which is not the case with skating.
Hans
Chris,
Do you or anybody else have acces to the full article. I would like to be informed in more depth about the whole context.
Hans
Interesting info, however touch an LP with something as hot as 70C and you will most likely permanently damage the LP, so excuse me, but I have my doubts.
As long as the LP is playing not too much will happen but when it stops playing the hot stylus would glue itself to the Viny while cooling down, at least that’s what I would expect to happen.
Hans
In that age and time (mid 70's) an IR camera was a little bit unwieldy. But it's not entirely implausible, the melting point of vinyl is 100 degrees centigrade and even the glass transition point is 82 degrees centigrade. Also, you can imagine the temperature drops really quickly once the friction heat disappears so 70 degrees centigrade while in constant motion seems to fall within the possibilities.
That said, I'd never advise to store records at 70 degrees
and I'm even not very enthousiastic about leaving a stylus on the record stationary.
That said, I'd never advise to store records at 70 degrees
and I'm even not very enthousiastic about leaving a stylus on the record stationary.Mark,
I’m with you for as far your calculation goes to 3 mW.
However this uses a high friction coefficient of 0.3 where other figures of 0.1 for amorph PVC are to be found. This would already reduce the 3mW to 1mW.
However probably because of the mixture with 20% crystalline additive, the friction coefficient must even be much lower as 0.1 or else the situation would be comparable to steel and that’s where the whole discussion started.
But I agree with you that thermal issues because of friction don’t play an important role, because like skating, friction must be extremely low.
Hans
Newbie post :
- may be we are over estimating heat generated as it has been shown (have seen some pictures of groove wall smoothening in some diyAudio thread) the vinyl surface smoothes out. So does diamond. So there is less friction and more contact area.
- moving surface gives some airflow around stylus vinyl contact.
- just like we can quickly move finger across candle flame the heat does not get transfered to vinyl from diamond tip as much.
- steel vinyl master is stiff so there may be less longitudinal flextures compared to vinyl.
- May be steel master heat gets spread to adjacent grooves so playing next track damages (heat buildup) so steel master gets easily damaged comparatively.
- Diamond stylus are mostly attached to aluminum cantilever so some heat may get transfered to it.
- Point to ponder : though vinyl cut master may be different material while cutting a disc the heated stylus does melt record and it does cool down (probably) immediately. Compared to that actual vinyl playing may have trivially small energy to make significant changes to occur, measured and studied.
When cutting a disc, the process is not comparable with playing a disc. The master is cut into either laquer on an aluminium or steel substrate, or copper, and the groove is actually cut into it. There is really a string of cut material that is sucked away. The chisel is not heated, actually the head is cooled and quite agressively. For a picture see the cutting head
The construction of the head is kind of similar to a moving-magnet cartridge except that the coils are driven with about 600W / channel.
The construction of the head is kind of similar to a moving-magnet cartridge except that the coils are driven with about 600W / channel.
Unfortunately that Audio Engineering Department is long gone and forgotten. It was the one for PolyGram, in Baarn. The big record manufacturing plant was also in Baarn, but it's completely gone and that part of town has been rebuilt.
My job there was actually checking out Studer A80's electronically and some other things, but that was the place where the PolyGram mixing consoles were made. I worked there for 2 1/2 years and had a blast
My job there was actually checking out Studer A80's electronically and some other things, but that was the place where the PolyGram mixing consoles were made. I worked there for 2 1/2 years and had a blast
Let's zoom out for a moment and then consider what the 'average consumer' knows or cares about these days. What I am noticing is that the reason that I find this thread so very fascinating is that even when I ponder just such subjects, I am barely getting information that I need for understanding something seemingly simple as all of this. Now when I attempt to discuss this with just about anyone locally, I get that look. Oops, should have talking sports or farming.
It's just this. if you so much as see a leaf blowing on the limb of a tree and you stop at that, you are missing the majority of what is actually happening.
It twists (exercises) my mind to read threads like this AND not have the usual BS or fighting ("Oh yah! You don't even know what science is! Take that!"... sigh) that I too often witness during exchanges. Thanks guys.
It's just this. if you so much as see a leaf blowing on the limb of a tree and you stop at that, you are missing the majority of what is actually happening.
It twists (exercises) my mind to read threads like this AND not have the usual BS or fighting ("Oh yah! You don't even know what science is! Take that!"... sigh) that I too often witness during exchanges. Thanks guys.
Wasn’t this transferred into the later Polyhymnia ?Unfortunately that Audio Engineering Department is long gone and forgotten. It was the one for PolyGram, in Baarn. The big record manufacturing plant was also in Baarn, but it's completely gone and that part of town has been rebuilt.
My job there was actually checking out Studer A80's electronically and some other things, but that was the place where the PolyGram mixing consoles were made. I worked there for 2 1/2 years and had a blast
I bought my Quad ESL’s from them, a special sturdy Philips version.
That’s about 15 years ago and they played ever since without any problem.
Hans
Actually I found out a little while ago that PolyHymnia still exists and even still at the old address at the Prinses Marielaan where they always were.
Back then they were part of PolyGram, they did the recording for classic music, many things for Deutsche Grammophon for example. They didn't need a studio, basically they went on site to a big church or concert hall with a couple 4 track recorders in special low-noise flightcases, a modest Philips mixing console and an assortments of microphones (mostly Neumanns).
When coming back home they monitored all their stuff on the ESL's indeed -- and I take it you indeed have the special ones with the silver screens!! Which makes me very jealous but I make do with a couple "ordinary" ones that I soon hope to supplement with a couple Ripole subwoofers (another glacial DIY project but it WILL be complete some day).
Back then they were part of PolyGram, they did the recording for classic music, many things for Deutsche Grammophon for example. They didn't need a studio, basically they went on site to a big church or concert hall with a couple 4 track recorders in special low-noise flightcases, a modest Philips mixing console and an assortments of microphones (mostly Neumanns).
When coming back home they monitored all their stuff on the ESL's indeed -- and I take it you indeed have the special ones with the silver screens!! Which makes me very jealous
but I make do with a couple "ordinary" ones that I soon hope to supplement with a couple Ripole subwoofers (another glacial DIY project but it WILL be complete some day).