Here's my calcs from a few years back as to vinyl and stylus heating. I look back on them as a bit naïve and I cringe a bit now, with the odd error too, but the logic still seems good to me and the result prediction might still not be far off I think.
This is the literal text, which I originally posted in 3 parts :
Decided to post my calcs on temp of stylus and vinyl in parts.
This is part 1, how much heat is generated. Source of heat is friction between groove and stylus.
From yosh's recspecs page citing JVC and other figures:
F = b*VTF
F is total friction force
b is coefficient of friction, 0.22 - 0.55 range
VTF is vertical tracking force
For typical b=0.4 and VTF=1.5gf, F=0.6gf=0.006N
For typical stylus velocity = 33cm/s =0.33m/s (inc rotation)
In one second, heat Q=0.006N*.0.33m=0.002 joules
Heat flow from stylus/groove friction P =0.002 joules per second = 2mW
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Here's part 2 of my calcs on temperature of stylus and vinyl.
Conclusion from part 1 is that typical heat flow rate at stylus/vinyl contact is of the order of 2mW.
Part 2 is a discussion of physics of what happens to the heat generated at the contact area.
At the contact area, diamond and vinyl materials mesh and are essentially a composite material in the region where friction takes place, not necessarily very deep, but essentially one material. Heat is generated by making and tearing apart this composite material, as the stylus traverses the vinyl surface.
Diamond is an exceptionally good conductor of heat. It has a coefficient of thermal conduction in range 900-2000, one of the best materials around. Vinyl is a poor conductor of heat, coefficient of thermal conduction 0.4 - 0.8. This means that approx 99.95% of the heat generated in the contact region is conducted by the diamond, and the tiny remainder 0.05% is conducted by the vinyl.
Before addressing the math calulating contact region temperature in the next part, note that virtually all heat flow is conducted away from this region through the diamond. Whatever the temperaure of the contact region, some 2mW * 0.0005 = 1uW is conducted by the vinyl. This is a very small heat flow !
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Here's part 3 of my calcs on temperature of stylus and vinyl.
Conclusion from part 1 is that typical heat flow rate at stylus/vinyl contact is of the order of 2mW. Conclusion of part 2 is that whatever the temperaure of the contact region, some 1uW is conducted into the vinyl, and this is effective heating power.
This is part 3 and looks at temperature rise of vinyl near the contact region.
Vinyl contact region continuously changes as record moves.
Assume contact region has a surface radius of 3um, stylus/vinyl velocity = 0.33m/s.
In one second, area swept by contact region A = 3um * 0.33*10E+6 um = 10E+6 um^2
From part 2, heat flow rate into vinyl from contact region P = 1uW
then heat flux into vinyl groove wall Y = P/A = 1uW/10E+6 um^2 = 10E-12 W per um
1um^2 = 10E-12 m^2
then Y = 1 W per square meter
For vinyl groove skin depth of 0.1um, volume swept by contact region in one second V
V= A * 0.1um = 10E+6 um^2 * 0.1 um = 10E+5 um^3
1 um^3 = 10E-18 m^3
V = 10E-13 m^3
Specific gravity of vinyl is close to 1 g/cm^3 = 10E6 g/m^3
Weight of vinyl occupied by volume W = V * 10E6 g/m^3
W = 10E-7 g = 0.1ug
In one second, heat flow = 1 uJ
Specific heat of vinyl is close to 1J/gK
Then average temperature rise T of vinyl groove wall skin to thickness of 0.1um
T = 1 uJ / 0.1ug = 10 deg K (celsius)
Obviously, convenient typical values were chosen to make the math plain, but these choices seem reasonable. Point is, there is not significant heating of the vinyl groove wall skin, not enough to melt or deform.
This is the literal text, which I originally posted in 3 parts :
Decided to post my calcs on temp of stylus and vinyl in parts.
This is part 1, how much heat is generated. Source of heat is friction between groove and stylus.
From yosh's recspecs page citing JVC and other figures:
F = b*VTF
F is total friction force
b is coefficient of friction, 0.22 - 0.55 range
VTF is vertical tracking force
For typical b=0.4 and VTF=1.5gf, F=0.6gf=0.006N
For typical stylus velocity = 33cm/s =0.33m/s (inc rotation)
In one second, heat Q=0.006N*.0.33m=0.002 joules
Heat flow from stylus/groove friction P =0.002 joules per second = 2mW
------------------
Here's part 2 of my calcs on temperature of stylus and vinyl.
Conclusion from part 1 is that typical heat flow rate at stylus/vinyl contact is of the order of 2mW.
Part 2 is a discussion of physics of what happens to the heat generated at the contact area.
At the contact area, diamond and vinyl materials mesh and are essentially a composite material in the region where friction takes place, not necessarily very deep, but essentially one material. Heat is generated by making and tearing apart this composite material, as the stylus traverses the vinyl surface.
Diamond is an exceptionally good conductor of heat. It has a coefficient of thermal conduction in range 900-2000, one of the best materials around. Vinyl is a poor conductor of heat, coefficient of thermal conduction 0.4 - 0.8. This means that approx 99.95% of the heat generated in the contact region is conducted by the diamond, and the tiny remainder 0.05% is conducted by the vinyl.
Before addressing the math calulating contact region temperature in the next part, note that virtually all heat flow is conducted away from this region through the diamond. Whatever the temperaure of the contact region, some 2mW * 0.0005 = 1uW is conducted by the vinyl. This is a very small heat flow !
_________________
Here's part 3 of my calcs on temperature of stylus and vinyl.
Conclusion from part 1 is that typical heat flow rate at stylus/vinyl contact is of the order of 2mW. Conclusion of part 2 is that whatever the temperaure of the contact region, some 1uW is conducted into the vinyl, and this is effective heating power.
This is part 3 and looks at temperature rise of vinyl near the contact region.
Vinyl contact region continuously changes as record moves.
Assume contact region has a surface radius of 3um, stylus/vinyl velocity = 0.33m/s.
In one second, area swept by contact region A = 3um * 0.33*10E+6 um = 10E+6 um^2
From part 2, heat flow rate into vinyl from contact region P = 1uW
then heat flux into vinyl groove wall Y = P/A = 1uW/10E+6 um^2 = 10E-12 W per um
1um^2 = 10E-12 m^2
then Y = 1 W per square meter
For vinyl groove skin depth of 0.1um, volume swept by contact region in one second V
V= A * 0.1um = 10E+6 um^2 * 0.1 um = 10E+5 um^3
1 um^3 = 10E-18 m^3
V = 10E-13 m^3
Specific gravity of vinyl is close to 1 g/cm^3 = 10E6 g/m^3
Weight of vinyl occupied by volume W = V * 10E6 g/m^3
W = 10E-7 g = 0.1ug
In one second, heat flow = 1 uJ
Specific heat of vinyl is close to 1J/gK
Then average temperature rise T of vinyl groove wall skin to thickness of 0.1um
T = 1 uJ / 0.1ug = 10 deg K (celsius)
Obviously, convenient typical values were chosen to make the math plain, but these choices seem reasonable. Point is, there is not significant heating of the vinyl groove wall skin, not enough to melt or deform.
Despite often having a spot laser, they tend to be quite large area IME.......maybe they have improved. I did attach a tiny thermocouple to the top of a stylus shank with thermal adhesive, and only measured a few deg C rise, however the thermocouple would have been a significant thermal load. But I thought it was consistent with perhaps 15 deg C rise for the diamond (with no significant gradient within the diamond).
You have to use thermal conductivity and specific heat of filled vinyl, both of which are larger that the textbook numbers for pure PVC.
An IR sensor won't work- because of the tiny areas, you have a wavelength issue when trying to get sufficient spatial resolution. A thermistor won't work either because of its thermal mass. I truly believe that VdH was having us on a bit- this is an incredibly hard measurement to do and his number appears nonsensical.
An IR sensor won't work- because of the tiny areas, you have a wavelength issue when trying to get sufficient spatial resolution. A thermistor won't work either because of its thermal mass. I truly believe that VdH was having us on a bit- this is an incredibly hard measurement to do and his number appears nonsensical.
It's a safe approximation to attach a small thermocouple to the cantilever, which is what I've done, and obtained negligible temp rise.
The value of IR imaging would be in viewing any trail in the groove immediately after the stylus has passed. But the dimensions of the groove and the resolution required makes wavelength a problem - unless the groove is very hot and the trail very long, which seems unlikely. Tricky photography too.
The claimed measurement (from what I understand) isn't the cantilever, it's the contact area between groove and stylus. There's no way in the universe that the cantilever is going to be at 160 degrees.
Probably. I attached a thermocouple junction to the top of the stylus shank, at the point where it passes through the cantilever - just because that is as close as one can get. Temp rise was negligible, and that at least confirms something I suppose. The tiny contact location between stylus and groove is simply very difficult to observe directly, especially from a thermal point of view.
Luckydog - i agree closely with your calculation. A couple of years ago discussion with a friend based on 5mW max power input and assuming all drag power dissipated into the vinyl (totally erroneous given the vastly greater conductivity of diamond!); specific heat of vinyl in volume units is about 2J/cc/K and thermal diffusivity of vinyl at about 10^-7m^2/s - well, we got to an upper bound of 30degC rise.
Nothing is melting, that's for sure...
Nothing is melting, that's for sure...
well I just spent a very pleasant and possibly expensive 23 mins listening to a side of Delos DMS3006 http://www.discogs.com/Liszt-Ravel-...r-Music-Of-The-Impressionists/release/2527181 1983 soundstream recording, recorded and mastered by stan ricker and pressed in japan by JVC. beautifully quiet vinyl and I want more.
now spinning a 1970 philips pressing of mozart piano and listening to the odd crackle there and trying to decide if they are dust or damage related. Only rare and generally left channel. As if on cue one that was defiantly dirt appeared, so I now understand what lucky was talking about
Hmm and track 2 has none of the ticks... fascinating.
now spinning a 1970 philips pressing of mozart piano and listening to the odd crackle there and trying to decide if they are dust or damage related. Only rare and generally left channel. As if on cue one that was defiantly dirt appeared, so I now understand what lucky was talking about
Hmm and track 2 has none of the ticks... fascinating.
Probably neither dust nor damage, Bill. More likely just random variation in friction, base on my experience of Philips classical pressings from the era. I have a fairly large collection of classical vinyl, including many Philips pressings.
Yes, often the two sides can have different intrinsic surface noise IME. This is another loose end, I doubt it is down to wear or dirt as most of my collection is lightly played, if at all. Neither can it simply be caused by composition or pressing process, you'd think. I don't know why.
There's a particular box set on Philips where I'm fond of the performance - Brendel playing complete Beethoven sonatas, perhaps on 10 records. Some sides show excessive surface noise, some are silent. Some have surface noise on one side of the record. Though I didn't own it from new, there's no sign the set was ever played before I bought it. On this set, no amount of cleaning shifted the surface noise, makes it worse in fact.
I listen to a lot of classical vinyl from the 50s thru 80s, perhaps that is why I'm a bit compulsive about surface noise !? Philips is not my favourite label from that era, but artists like Haitink make it worthwhile. But the ending of the last movement of say Mahler 9 really really really does need quiet vinyl. Decca is my favourite label, just for shear beauty of recording, and the pressings are generally superb and as crackle-pop free as there is IME.
Interesting. The fact that side one went almost silent after the first track does still indicate to me that there it was some form of playback issue.
Until recently I ignored mono until one of my ebay purchases contained a mono DG recording that was simply stunning. now I am seriously considering a mono only setup if I can find room for a second turntable.
When I was buying new vinyl back in the 80s I generally went for specialist labels such as BIS, CRD , caliope, hyperion and nimbus. But as soon as I grew out the audiophile phase have realised that there are some amazing recordings and pressings out there on many labels.
Horrendously OT: I have to say I love the decca sound analog years box set I got for xmas. I can't currently afford any of the other box sets they are doing (or the MLP 3 set sob), but the reissues are great if you don't have the originals. However I do now want some of the originals!
Dangerous website of the day for me: Rare and collectable LPs, CDs, 45s and EPs from Jane Delawney. Classical LPs 1 to 10. under £2 gets my buy finger twitching
Until recently I ignored mono until one of my ebay purchases contained a mono DG recording that was simply stunning. now I am seriously considering a mono only setup if I can find room for a second turntable.
When I was buying new vinyl back in the 80s I generally went for specialist labels such as BIS, CRD , caliope, hyperion and nimbus. But as soon as I grew out the audiophile phase have realised that there are some amazing recordings and pressings out there on many labels.
Horrendously OT: I have to say I love the decca sound analog years box set I got for xmas. I can't currently afford any of the other box sets they are doing (or the MLP 3 set sob), but the reissues are great if you don't have the originals. However I do now want some of the originals!
Dangerous website of the day for me: Rare and collectable LPs, CDs, 45s and EPs from Jane Delawney. Classical LPs 1 to 10. under £2 gets my buy finger twitching
As a former polymer Chemist and someone that has worked in the surface coatings industry for 25 years, I doubt there is another plastic moulded product in the world that has such exacting surface finish characteristics straight off the press. It is hardly surprising that there will be slight imperfections from time to time in the quality of the surface (indeed it is amazing that there are such good examples out there).
When polymers solidify natural inhomogeneities in the composition of the melt (for instance pooling of flow additives, mould release additives, low molecular weight fractions etc) will be frozen in place, making some areas stickier than others. The coefficient of friction of the bulk material is an average, there will be very small domains where this coefficient of friction will vary. Whether this would be sufficient to cause a pop or click though, I couldn't say.
Just be amazed that this technology works at all...I certainly am!
When polymers solidify natural inhomogeneities in the composition of the melt (for instance pooling of flow additives, mould release additives, low molecular weight fractions etc) will be frozen in place, making some areas stickier than others. The coefficient of friction of the bulk material is an average, there will be very small domains where this coefficient of friction will vary. Whether this would be sufficient to cause a pop or click though, I couldn't say.
Just be amazed that this technology works at all...I certainly am!
Yes. Level of random variation in friction depends on stylus velocity, so below a certain velocity friction is very seldom sufficient to cause momentary loss of contact, hence playback becomes quiet. The problem is worse therefore on outer tracks. The probability of a random spike happening follows a flicker law, which crops up in nature quite often. So chance of a spike at any moment is governed by this law, but amplitude of the spike depends on velocity. Below a certain amplitude it doesn't cause loss of contact so isn't audible.
Yes, I have a dedicated mono setup. What got me back in to vinyl, only about 6 years ago, was I inherited a copy of a 1952 Decca mono recording of 4 Last Songs, Lisa Della Casa and Karl Bohm. So I felt obliged to play it and got my old rig out of the loft. Not only was the performance spine tingling, but the realism of the recording and playback just knocked me out. And I was hooked on seeing just how good it could get, given that what is physically recorded in the grooves seems to be such a good transcription. That record is still very special to me.billshurv said:
Go for it ! Look out for Decca SXL, especially the 2xxx range, but also Ace of Diamonds which used the same stampers and are more available and cheaper. Decca SXL, back in the day cost about the same as an average weekly wage - the equivalent of a couple of hundred quid in current money...............
BTW, hope the hospital matters resolved OK Bill.
I am sorry SY.
I thought your concerns over IR spatial resolution were triggered by my post:
George
@thickmike: Oh yes I am amazed. Despite everything that is compromised about vinyl it can sound very satisfying
@Luckythedog: Thank you for asking. Last antibiotics at 4AM tomorrow then I bring them both home in the morning. Looking forward to it as are brood 1. I do have some ebay deccas that I will dig out for a spin. On your analog rig do you have a collection of stylii for mono or have you picked one that seems to be sweet spot for most?
@Luckythedog: Thank you for asking. Last antibiotics at 4AM tomorrow then I bring them both home in the morning. Looking forward to it as are brood 1. I do have some ebay deccas that I will dig out for a spin. On your analog rig do you have a collection of stylii for mono or have you picked one that seems to be sweet spot for most?
That was to Jan and lucky, sorry to be unclear. You could measure the cantilever, but it's not of much relevance to determining the truth (or lack thereof) of the temperature claim made by someone selling styli who, in the finest traditions of high end audio, won't give any detail on how he got the numbers he's using in his promotion.
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