Dgarretson, it might be helpful to look at how a record is cut. A worm drive advances the cutter across the record- so to play back, it seems as if a linear tracking device will be needed, although there are some interesting approaches that use radial arm systems, like the Thales arm.
You have the issue of warps and bass- this means, to prevent variation in tracking pressure, that the arm bearings be in the same plane as the vinyl. When the bearings are above the LP surface, the tracking pressure will decrease with bass or warps.
The azimuth must not change during playback either. A gimbaled bearing will work for this and may not be the only means.
A short pivot will not work, as it forces the bearings to be above the LP surface, and makes for audible speed variation as warps are negotiated.
Air bearings don't seem to work either, as it will be seen that the more air pressure is used, the better they work. There are mechanical bearings that have no 'slop' or play in the bearings; play at this point is critical as any (even microscopic) movement is interpreted as a signal by the transducer. You want the motion of the needle to be paramount, without editorial by other parts of the system.
Now it will be seen by some that my comments might appear inflammatory to some. But I am simply outlining what appears to be needed. The digression of opinion is likely based on philosophy rather than anything tangible. That is how wide open the tone arm arena still is.
You have the issue of warps and bass- this means, to prevent variation in tracking pressure, that the arm bearings be in the same plane as the vinyl. When the bearings are above the LP surface, the tracking pressure will decrease with bass or warps.
The azimuth must not change during playback either. A gimbaled bearing will work for this and may not be the only means.
A short pivot will not work, as it forces the bearings to be above the LP surface, and makes for audible speed variation as warps are negotiated.
Air bearings don't seem to work either, as it will be seen that the more air pressure is used, the better they work. There are mechanical bearings that have no 'slop' or play in the bearings; play at this point is critical as any (even microscopic) movement is interpreted as a signal by the transducer. You want the motion of the needle to be paramount, without editorial by other parts of the system.
Now it will be seen by some that my comments might appear inflammatory to some. But I am simply outlining what appears to be needed. The digression of opinion is likely based on philosophy rather than anything tangible. That is how wide open the tone arm arena still is.