Ancient AR Turntable with NO anti skate

Norman,

There are many considerations we're aware of today that were not well known or appreciated in the 1950s and early '60s.  

Another example was cartridge alignment (overhang and offset).  While some engineers studied this even pre-WW2, it did not become more broadly known until the mid-late '70s after an article by Mitch Cotter was published in "The Audio Critic".  That magazine may have elicited concerns for other reasons but credit is due for raising awareness to the importance of proper cartridge alignment.

In spite of such limitations, some older tables such as the AR-XA are still capable of providing a satisfying musical experience, just as you learned.

Norman, it sounds like you found your solution, good to see that.

I don’t know how early manufacturers became aware of skating? If I remember correctly several arm/table combinations included separate recommended settings for conical and elliptical styli. Also, having owned a few Shure cartridges I would always purchase one of their test records for each model. Those (all?) included a blank (ungroved) band to set anti-skate, something I dutifully followed. But later, like Al, I read why that was not accurate. I also remember reading something from Thorens or Ortofon that the force does indeed change as the stylus tracks the radius of the record. At that point, not being an engineer, I began setting the anti-skate at approximately 80% of the VTF value and quit worrying about it. ;^)

Also many know that Harry Weisfeld believes anti-skate is unnecessary and initially didn’t include it on his VPI arms, other than by "twisting" the connecting wiring. Later on he offered it as an accessory, I assumed due to consumer demand.

Norman,

I believe you are correct the Rabco was the first accessory (separate component) tangental arm.  But by the late '70s several Japanese companies offered tables with tangental arms.  I had one of the Pioneer units (picked up in Japan by a Navy buddy) which was nearly the same as the Phase Linear version sold in the US.

Bruce Thigpen worked for Maplenoll, designing their air-bearing tangental arm prior to starting his own company, Eminent Technology, in 1982.  The first ET product was an improved version of that arm.  During the '80s Souther and other companies also introduced tangental tracking arms.

Back to the AR, VTF was not the only adjustment with that arm.  There is a set-screw on the underside to adjust arm length for stylus overhang.  However offset is fixed because headshell slots are not provided.

Norman,

The details are over my head but consider this general view.

When modern records are cut they are not done so with even groove spacing.  Instead the mastering engineer may adjust spacing based upon the dynamics of the music being recorded, along with how much play time is desired to be accommodate on a record side.

So even with playback utilizing a tangental arm, how will the arm be controlled to maintain perfect tangency with variable groove spacing?  It is my understanding that two different methods have been utilized.  I believe most of the arm/table combinations have sensors which read arm position and mechanically move it to maintain the cartridge/stylus perpendicular to the groove.  This means some degree of correction is always in play.  The second method is to allow the stylus to "pull" the arm across the record.  Obviously absolute minimal friction is needed for this to be successful which led to development of air-bearing arms.

Neither of these methods is simple or inexpensive to execute, and thus the emphasis on pivoted arms, being simpler to design and less expensive to produce.

I suspect this is similar to the situation why belt-drive tables became so dominant over direct drive and idler designs.