Spindle oil

100 deg C/212F on a stylus tip?? Yow, can you find a thermocouple small enough to fit on a cantilever? Can you get a handheld infrared gun with a small enough beam pattern? Can you measure this with an infrared thermography device??

Back to lubes; the more I think about it, I wonder how many square inches of contact area are on the tip of the spindle bearing and it's contact plate. Mighty small... Seems to me like this is going to have to be a regular maintenance item - lubing the spindle bearing.

Herman: If the stylus wasn't "scraping" its' way through the vinyl troughs, it wouldn't be generating heat at the tip. That heat is wasted energy due to unnecessary friction. It's pretty simple when you break it down.

Amplitude modulations in the vinyl surface should simply produce vertical displacement of the cantilever. This vertical displacement is the result of energy transfer, which produces voltage from the cartridge and the accompanying music from your phono stage. There is some horizontal deflection also as there are various amplitude passages that occur in one channel that don't occur simultaneously in the other channel. This is what gives us output in the individual right / left channels.

As such, the "friction" between the stylus and the vinyl groove comes from the fact that the stylus is NOT centered in the mass majority of grooves. As a result, the cantilever is constantly being twisted rather than being pushed up and down on loud to quiet passages or side to side during left to right / right to left signal changes. This is how records get "worn out" due to the "cutting action" of the diamond "dragging" across the sides of the grooves, not through the center of the grooves.

If you can align the stylus in a fashion that it stays relatively centered in the grooves, you'll find that surface noise is drastically reduced and stylus' will last a LONG time. Then again, you can't ever hope to achieve this type of performance from a pivoted arm due to the very nature of the design.

As to your comments about servo's, they can be made quite fast and quite good. Compared to a pivoted arm that can only be correct in two places ( at best ) along the entire side of an LP, i'll take a well designed servo controlled linear tracker any day of the week. I would rather have something that was "very close" most of the time as compared to something that was "rarely correct" at best due to the law of averages.

As far as introducing more drag to compensate for other drag, that sounds like complimentary colourations to me. Neither is "right", but you end up with something that is bearable. It's not necessarily "good", but it works. Like i said, you can throw money at a design, but that doesn't make it good. It might be better than others of similar design, but that doesn't make it good. It just makes it slightly better than "poor" because it isn't quite as obvious due to the blatant errors being covered up. Sean
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Sean, your seeming inability to even hint at the possibility that you might be wrong makes it impossible to discuss this in a logical manner. I'm leaving the topic after this.

First you claimed that the stylus was "slicing" through the vinyl like a diamond cutter through glass. When I point out you are wrong because it is "riding along the surface" you change to "scraping," which is in effect exactly the same thing I just said, and make a condescending remark like I don't get it. You should go into politics.

The heat isn't generated simply because the stylus isn't centered. It comes from the stylus tracking the modulations. Heavily modulated grooves produce more heat than lightly modulated ones no matter how well centered the stylus is. Centering has nothing to do with it.

This is a well proven fact, not an opinion. You are wrong. No matter how many times you put forth the centering argument, you will still be wrong.

Also, there isn't a manufacturer in the world that uses a servo motor controller to compensate for instantaneous stylus drag. Why? It won't work. No matter how fast, servos will always be reacting to something that happened in the past. Again, not an opinion. It is a fact that you are unwilling to acknowledge.

All servo controlled linear arms to date have been inferior to other designs for the same reasons. This is also a fact. I do believe given the advances in servo motors since the attempts in the early 80's, and the speed of todays microprocessors, that it should be possible to build one that will work well. Perhaps combining the tracking capabilities of the newer laser tonearms as the feedback to the controller along with high speed processors might work. The laser tracker could be positioned ahead of the stylus, in effect predicting where it needs to be instead of reacting to it being where it shouldn't be. Feel free to use and develop that idea.

Herman...There are servos, and there are servos. The faults you cite can be avoided. The microprocessor controlled linear tracking arm on my Sony PS X-800 TT maintains tracking angle within 0.05 degree across the entire disc, even when the groove spacing is variable. No pivoting arm can do this.

By the way, like all linear tracking arms, many other problems such as skating force are eliminated entirely.

But this was supposed to be about spindle oil. Damping, viscous or otherwise, can stabilize a servo that tends to oscillate. Consider the shocks on your car...without them you would bounce a lot. Speed regulation in the presence of variable friction is the job of the platter inertia, at least at a frequency higher than what can be followed by the speed control servo of a direct drive table. If there is no speed control servo, there will be some slowing down.
However, the stylus drag variation is so small, and turntable motors so powerful, relative to the drag they overcome, that I doubt any noticable slowdown actually occurs.

El: Speaking of shock's and servo's, one might find this servo-related suspension system designed by Bose to be of interest. I would suggest looking at the whole article and then watching the videos at the end. Quite impressive if actually performed / tested in an even-handed manner.

Herman: My specific choice of wording may have been poor and lacking in continuity, but i meant the same thing. When a diamond is "scraping" or "dragging" across the side-walls of the vinyl, it IS "carving" through the vinyl. This is what causes sonic degradation, groove distortion, stylus wear and heat.

As far as stylus temperature goes, the cantilever will act as a heatsink for what would be "normal" drag. That is, the type of material that the cantilever is made of will depend on how efficiently it absorbs and radiates heat. After all, there IS going to be a certain amount of drag / heat as the diamond and the vinyl are in direct contact ( hopefully ) and the vinyl is in motion. More modulation "should" simply cause more vertical deflection, which "should" be transmitted strictly as mechanized energy. This generates electricity in the motor structure of the phono pick-up, not heat at the tip from "scrubbing" due to mis-alignment. How efficiently this mechanized energy is converted to electricity without loss will depend on the rigidity of the cantilever, the tracking ability of the cartridge, how "correctly" the cartridge / arm interphase is set up, etc...

YES, there IS going to be drag in a vinyl system. The key here is to minimize it and have a system that maintains proper operating speed with high stability. If properly designed, the platter will have enough inertial mass and be balanced well enough to maintain a steady speed even with varying levels of groove modulation. The motor should have enough torque to "muscle" the mass of the platter as needed and the system monitoring the speed should check and update often enough to make the proper adjustments without the speed varying too far out of tolerance.

Reducing the friction at the bearing simply means less energy lost i.e. closer to perpetual motion of the platter due to less "rolling resistance". Once this has been addressed in the bearing / platter support structure by using proper machine tolerances and the proper lubrication, the platter spins freely, both more consistently and longer due to less drag. If the machining was well performed and the lubrication itself doesn't introduce drag inconsistincies due to surface tension ( how "slippery it is" ), the result is a reduction in frictional losses. With less frictional losses, we need less error correction from the speed monitoring device to come into play. This in turn reduces the vibration from the motor as it isn't lurching or clutching due to the reduction in speed adjustment needed.

The only drag involved in such a system would be that of the centered stylus in the groove, which inertia from the weighted platter should pretty much take care of most of the time. Since we haven't been able to design a "lossless" mechanical system, the motor and speed correction devices are still needed though. That's because the tracking force of the stylus is introducing loss into the system along with the minimal amount of drag that we can't get rid of in the bearing. Obviously, the less friction in the bearing, the less drag / vibration in the whole turntable due to the domino effect of losses & correction involved. Sean
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