Well, my suggestion might be a stretch, but two little points in addition. First, the deformation of the vinyl starts before the stylus arrives at a specific point, so it is heated up from elastic deformation before it is hit by the tip. Second, friction is a second source of heating, but like with disc brakes, it will dissipate in proportion to the thermal resistance of the two surfaces rubbing together.
In this particular instance, the way of the lesser thermal resistance may well be the diamond tip, all the more so because the vinyl has already been preheated by compression.
Vacuphile,
This is a mechanical engineering problem to solve. You also have to look at the heat dissipation factor of the vinyl itself and the large mass of that material compared to the small localized heated area.
This is a mechanical engineering problem to solve. You also have to look at the heat dissipation factor of the vinyl itself and the large mass of that material compared to the small localized heated area.
Deformation and rebound will be a pretty small contributor, I think- if it were not so, you couldn't resolve high frequencies. I did a back-of-the-envelope heating calculation from friction (assuming the mu given in the linked paper, a thermal conductivity of vinyl of 0.3J/s, and a vinyl heat capacity of 1.1 kg m2/s2, and would like to fancy it up a bit, but if we take a worst-case where no heat is absorbed and transferred by the tip and cantilever, the heating is insanely small, I mean smaller than 0.01K. This assumes volume of vinyl large with respect to the stylus contact area and 1g/10mN tracking force.
What non-Ohmic behaviour?
Ed, do you imply a Peltier vs Seebeck tennis game along the wire?
Easy with this! All the tubes in the world will jump on you
Mercury goes with Pt, Ni, Mo, Fe, contacts.
When I go to measure very low DC voltages…
You lost me there 🙂
George
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The old way to make a precision measurement of a small voltage in a cal lab was to use an optical galvanometer and carefully balance the known voltage to the unknown until the optics were at the samme position as when disconnected. At that setting no current was passing through the galvo and the voltage potentials were the same. Today you use a 6-8 digit DVM instead of the galvo, but the rest of the bridge is pretty much the same. Its all really tedious and slow. Normally that DVM is plenty accurate.
Here's a reference to another calculation of friction induced heat rise in vinyl playback confirming SY's post (look for "goneawol" near the bottom of page):
Turntable Forum • conical versus ellipticals
And here's a relevant bibliography including reference to Pardee's value of about .25 to .3 for coefficient of friction (about as expected from anti-skating values):
Turntable Forum • Frictional heating of vinyl revisited
which also has interesting comments about whether elastic vs. plastic deformation occurs.
Thanks,
Chris
Turntable Forum • conical versus ellipticals
And here's a relevant bibliography including reference to Pardee's value of about .25 to .3 for coefficient of friction (about as expected from anti-skating values):
Turntable Forum • Frictional heating of vinyl revisited
which also has interesting comments about whether elastic vs. plastic deformation occurs.
Thanks,
Chris
This is a fascinating history of wire gauge measurements: The story of the gauge - P[]ll - 2002 - Anaesthesia - Wiley Online Library Gauge seems to mostly relate to how many times the wire was passed through a drawing die. It actually makes sense even if not relating to familiar dimensions.
Sheet metal is also gauged originally by the number of passes under a specific roller.
Sheet metal is also gauged originally by the number of passes under a specific roller.
I had hear some years ago that water will affect the plasticizers in PVC. Records usually have a carbon filler (the black stuff) to make them more wear resistant. Perhaps the water strips some of the carbon out and then you need the water to lubricate the surface afterwards? There are others here who should actually know this stuff.
This What gives PVC its weather resistant qualities? | Veka Inc. - Ask The Expert Suggests that there is a lot going on in PVC.
This What gives PVC its weather resistant qualities? | Veka Inc. - Ask The Expert Suggests that there is a lot going on in PVC.
Demian,
Somewhere on this thread or in another we had this discussion with Sy and if I remember that correctly he stated there are no plasticizers added to the material in an album. There were no materials to leach out of the materials used, especially by a water reaction. Only thing the water would do is leave mineral deposits if it was not DI water.
Somewhere on this thread or in another we had this discussion with Sy and if I remember that correctly he stated there are no plasticizers added to the material in an album. There were no materials to leach out of the materials used, especially by a water reaction. Only thing the water would do is leave mineral deposits if it was not DI water.
Wire should be specified in mm diameter or mm squared cross sectional area. Its good to note the brits have (largely) thrown out the imperial system and adopted the much more sensible metric system. Same for the cheese and the wine BTW 😀
For those who need a little guidance 🙂, here's a good place to start ... http://www.diyaudio.com/forums/loun...rch-preamplifier-part-ii-987.html#post2474862
> Would it not be possible to calculate the energy from the friction of the needle over the vinyl? We know dimensions of the tip, tip force, tracking speed ...?
There is a simpler way Jan. 😉
Just measure the increase in current of the turntable motor.
Multiply by the voltage, then you have the value you want.
Patrick
There is a simpler way Jan. 😉
Just measure the increase in current of the turntable motor.
Multiply by the voltage, then you have the value you want.
Patrick
Steven,
Look for SY’s posts in this thread:
http://www.diyaudio.com/forums/analogue-source/220542-riders-storm.html
George
Look for SY’s posts in this thread:
http://www.diyaudio.com/forums/analogue-source/220542-riders-storm.html
George
One more note about vinyl playback and I'll give it a rest for the night.
SAS gives some sample stylus-vinyl contact areas (whatever that means for an elastic medium):
S.A.S Super Analogue Stylus | JICO stylus | Online Shopping for Japanese Phonograph Needles
where we can choose a representative sample of say 25 micrometers squared, or 2.5 10(exp -5) m(exp 2). Then pick a representative moving mass of say .25 grams.
At an acceleration of 10(exp 4) m/s(exp 2), (about 1000 G's, somewhat higher peak values aren't too rare) the force exerted by the vinyl on the stylus is 2.5 10(exp -3) Newtons.
Pressure is then 2.5 10(exp -3) / 2.5 10(exp -5) = 100 Pa = 689500 psi or 344 tons per square inch peak.
Thanks,
Chris
SAS gives some sample stylus-vinyl contact areas (whatever that means for an elastic medium):
S.A.S Super Analogue Stylus | JICO stylus | Online Shopping for Japanese Phonograph Needles
where we can choose a representative sample of say 25 micrometers squared, or 2.5 10(exp -5) m(exp 2). Then pick a representative moving mass of say .25 grams.
At an acceleration of 10(exp 4) m/s(exp 2), (about 1000 G's, somewhat higher peak values aren't too rare) the force exerted by the vinyl on the stylus is 2.5 10(exp -3) Newtons.
Pressure is then 2.5 10(exp -3) / 2.5 10(exp -5) = 100 Pa = 689500 psi or 344 tons per square inch peak.
Thanks,
Chris
Neat! But then you also need the efficiency of motor input power to rotation of the platter, no?
Jan
Pardee's method is actually pretty similar. He pushes the platter with record up to speed, lets it coast, and times its deceleration.
Thanks,
Chris
Thanks,
Chris
I don't think you could measure a power difference that small. The friction in even an air bearing motor system is greater than the drag from the stylus. The actual power to keep the turntable running is very small. The losses in the motor are high by comparison. You could check the drag by timing the difference in 33.3 RPM to 0 stylus on vs. stylus off. I have not see an appreciable difference myself. If the turntable has an encoder its even easier and more accurate using the encoder.
I like the deceleration method. 😉
But you need to know the inertia of the total rotational system rather accurately.
Patrick
But you need to know the inertia of the total rotational system rather accurately.
Patrick
My Goldmund TT has a platter mass of 20 kg, belt drive, electronic speed regulation, Motor power maybe 3-5 Watts, needs apx 15 seconds for stable speed, has a tachymeter, when the stylus is going down in the groove, the tachymeter shows speed drop from 33, 33 down to 33, 31 and stabilizes within 2 seconds again at 33,33.
Switching off ist stops within 10 seconds with motor load, without motor/belt apx 1 Minute.
The spheric tip has a contact surface of 30 square micrometer and runs at 2,5 gramms ( This is equivalent of 8300 Kilogramms per squarecentimeter)
My EMT TT has 7 Kg platter mass, most at the outer side, idler wheel drive, the motor is 30 Watts, 3 Phase synchron with 50 Hz, no regulation, but felt brake for continous load and speed adjusment.
When switched on it has full speed below 1 second, when using the subtable fast start it is specified to be lesser than 600 milliseconds and its rockstable with speed, with or without stylus.
Speed deviations are lower than the best test records you can get.
So we must have a different method to measure the friction.
The friction is not static due modulation, in a empty groove we track between 20 cm und 50 cm per second, in modulated groove it will vary, on one hand we have a longer path , reducing the dynamic pressure, on the other hand we have more friction due tip acceleration and sometimes resonances in the area between 3 and 15 Hz.😕
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