Sorry, but I don't get it
Pulling Force = (Kinetic Frict coeff.) x (Force Perpendicular)
Energy is the integral over the length of the road X PullingForce
So there is pulling force when there is a KFC > 0 and a FP >0
And energy is consumed when travelling a distance while pulling with a certain force.
Is there something incorrect in this ??
Hans
It's not a matter of energy. It's a matter of Newton's 1st law.
Stylus movement relative to the cartridge generator is necessary for signal output, but stylus-groove friction force does not cause this unless under the exceptional condition where friction force is momentarily so great that VTF is overcome.
If friction force is constant, this can't happen, VTF always retains the stylus against both groove walls, there is no extraneous movement of the stylus relative to the cartridge, therefore there is no noise.
It's not a matter of energy, except that momentary variation in friction force correlates with it. So outer tracks, having more total energy involved due to higher stylus-groove linear velocity, can have elevated crackle-pop noise depending on specifics.
Aside, for typical conditions, energy associated with stylus groove friction amounts to c 3uJ/s ie c 3uW or so power conversion. Most of the time, there is no stylus movement relative to the cartridge involved, and all the tiny amount of energy involved is associated with heat lost in groove walls and stylus. Stylus, being diamond, is an exceptional heat conductor away from the contact area. Groove wall is exposed to c 3uW for a few uS or so before moving on.
LD
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There are not that many things that we can agree upon, do we.
I fail to see why mr. Newton has te be waked up with his Inertia Law.
Let's simply agree that we disagree.
Hans
You are disagreeing with Newton, Hans, which isn't reasonable 🙄 Don't blame me, I didn't create the laws of physics, I'm just a messenger..........
LD
You're conflating energy with signal. You can dissipate energy in ways other than the generator (heat, for example!). If the friction is constant, there's no stylus motion laterally or vertically, just an offset, for which velocity is zero.
That's what I said in #319:
Energy to be converted into heat, into noise, into whatever but it cannot disappear into thin air.
I fully agree with you that a constant static force is not a reason to cause noise from a Cart motor.
But when one object is moving while pulled along another object, assuming that u>0, energy is not only converted into heat but also in some squeezing noise of whatever spectrum.
If that being the case with Cart / LP , it seems logically that this noise will be transferred into the Cart motor and converted into a signal, no matter how small it is.
Hans
No, we're talking about the frictional force with motion, separated into time dependent and time independent terms. BY DEFINITION, the latter term results in zero signal, all we get as signal is the first term, the CHANGE in friction with respect to time. The constant friction is dissipated as heat, not signal.
For energy to be converted into 'noise' the stylus has to move relative to the generator. But stylus is retained by groove walls, and by VTF via the cantilever: it is not free to move in the direction of applied friction force. So 'squeezing noise' force, ie random variation in stylus-groove friction force, is just balanced by an equal and opposite reaction via the cantilever/tonearm, and nothing moves. Unless a certain threshold of friction force is exceeded, in which case there is a net upforce and the stylus moves upwards. Newton.
OK, small is our new word. Cantilever flex/vinyl compliance, headshell movement, sort of small. Negligible by contrast to effect of crackle-pop micro-mistracking when stylus loses contact with groove resulting in crackle-pop, and having a totally different spectrum.
LD
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For energy to be converted into 'noise' the stylus has to move relative to the generator. But stylus is retained by groove walls, and by VTF via the cantilever: it is not free to move in the direction of applied friction force. So 'squeezing noise' force, ie random variation in stylus-groove friction force, is just balanced by an equal and opposite reaction via the cantilever/tonearm, and nothing moves. Unless a certain threshold of friction force is exceeded, in which case there is a net upforce and the stylus moves upwards. Newton. As soon as it does lose contact with groove wall(s) friction force disappears, so there is net downforce, and the stylus accelerates downwards again until it is in contact with the groove wall(s) again. This a short noise event. Crackle-pop noise is a series of such events of various amplitudes and random repetitions.
OK, small is our new word. Cantilever flex/vinyl compliance sort of small. Negligible by contrast to effect of crackle-pop micro-mistracking when stylus loses contact with groove resulting in crackle-pop, and having a totally different spectrum.
LD
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We are not that far apart. You can divide the force into an average non time dependent and a varying time dependent force.
Still with the non time dependent we have: Labour = Force x Distance, being independent of time.
So where does this energy go to ? In that it does not matter whether the LP or the Cart is moving, it concerns distance over a relative movement.
I am not perse against the statement that all this energy caused by Cart/LP friction is converted into heat, but I wonder how you can be so sure ?
That in fact is my main point in this very discussion, why is energy converted into just heat, why not also squeezing noise ?
If it is only heat, you are 100% right that no signal will come from the cart, but some evidence would be nice.
I don't expect that everybody is a superspecialist, like myself being just a critical observer.
But every now and then I see statements passing in different posting that are very doubtful and not substantiated to say the least.
Hans
Heat. If the friction is constant, there is no lateral or horizontal velocity, just a steady pull. A few seconds drawing the vector diagram will demonstrate this.
Do you have a reference on that? Calibration is the easy part, I'd like to see how that was done experimentally.
I would love to see that, a reference will do?
There's typically about 3uW heat flow available, and diamond conducts heat extraordinarily well. Contact region must be at virtually same temperature as the bulk, says physics of the calculation. Ultimately what small heat there is conducted by the cantilever and disappears through losses. I attached a tiny thermocouple to the top shank of a stylus some years ago, and though the experiment was far from perfect, I obtained no notable rise of temperature of the stylus bulk, within limits of +/- a degree or so.
As to melting vinyl, contact surface of groove wall is exposed to 3uW heat flow for a few uS. Common sense is readily confirmed by calculation that even to molecular depth, temp rise has to negligible and nothing can 'melt' in the classic sense.
As to using infrared to resolve tiny contact regions in situ in real time, I doubt it can be done. With a lot of skill, the bulk of the stylus might be observable.
Deeply sceptical, but would be very interested to see the reference.
LD
It's easy to observe acoustic noise and also measure the realtive motion of the arm/cart with micro-accelerometers.
I would also like to see the reference to contact temperature of the stylus in motion. I have never seen anything but speculation. Instrumenting this would be a lot of work.
Google still returns this type of obvious nonsense...
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You've got it, Hans. Hoorah !
Heat.
Newton. Nothing changes velocity. Conservation of energy.
Because something has to change velocity to produce noise.
LD
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When I said nothing moves, well it wouldn't except for tracking offset angle. This means that reaction force to stylus-groove friction is applied at an offset angle, so there is a resultant torque, known as skate force. The varying time dependent stylus-groove friction force causes variation in skate force.
Variation in skate force creates variation in torque applied to the mass of the headshell via the spring/damping of the cartridge suspension. The headshell, being free to pivot, can move relative to the stylus and therefore generate signal. How the headshell moves is governed by the spring-mass system of cartridge suspension and tonearm inertia. There will be a classic response to stimulus to frequency of stimulus centred about the c 10Hz cart-arm resonant frequency:
This is why LF cart-arm resonance amplitude correlates with stylus-groove friction coefficient.
Above the c 10Hz resonance, cartridge output rolls off at -40dB/decade. Typically, time dependant variable part of friction force, the stimulus, follows a -20dB/decade flicker law. So headshell motion, ie cartridge output, follows a -60dB/decade law above 10Hz or so, and is very much a LF phenomenum.
LD
Ok.
Resonance is caused by skating force, correlates with friction coefficient and roll off from 10hz is 60 dB/decade.
Nice to know.
Hans
Hi Scott,
To get some feeling about how much motion is involved, a 0dB 1Khz tone is recorded as a 36um pk/pk sinus, or an rms displacement value of 13um.
Dominantly white noise from a cart on a silent track lies ca -60dB below 0dB from 20Hz to 20Khz.
That implies that this noise will have an rms displacement of 13nm.
But the head will hardly move because of its much higher mass compared to the tip. So the movement of the head will be in the pico meters.
Just out of curiosity, will it be possible with a micro accelerometer to measure this kind of displacement ?
Hans
That was in print when I was a student of engineering, now I'm
zooming towards retirement much faster than I want...
Z80 times perhaps, if you are in computers.
It is not completely impossible that I still have it somewhere.
Heat conduction via the diamond does not count; even if we assume
that the generated heat appears evenly in the diamond and the
vinyl, the diamond will be unable to remove heat from the vinyl
because it is separated immediately from the hot spot.
The diamond itself is huge compared to the contact area.
regards, Gerhard