Spindle oil

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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El, I'm not familiar with your table but once had a Technics linear table with direct drive and a motor driven linear arm. They were all the rage back in the early eighties but fell out of favor with the high end crowd after proponents of belt drive platters and conventional pivoted arms convinced us that the former were inferior because the direct drive motor was always searching for the proper speed and the arm was crab walking across the record. Maybe it's true and maybe not, but as far as I know they did disappear from the market.

I do believe the best linear arms are capable of better peformance than the best pivoted arms. If they could just get the cost down to where I could afford one. In my price range I think the pivoted arms are superior but I'm not sure what all is out there in the linear world. Everything I see is in the $10,000 plus range.

"On top of that, there's no circulation system involved, so flow time isn't a concern." Not so for all TTs. Sean, you haven't considered the bearing design used by Tom Fletcher in his Nott. TTs. This design does 'pump' oil around the bearing sleeve.

John: Thanks for making me aware of that fact as i was not aware of it.

Herman: High quality linear tracking arms aren't that expensive. That is if you don't mind buying used, can shop around on the net and move fast once you find one. Sean
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