"those speed accuracy figures they publish are probably not measured at the platter level."
On a direct drive where else could the measurement be taken? Besides measurements would be pretty meaningless anyway. Yes the Japanese DD tables from the 80's perfected the art to the point of having superb measurements. The sound is also respectable given the price point, but they are not even in the same ballpark as the current start of the art. I think that the DD topology is inherently superior, but as with all high end audio equipment the magic is in the implementation.
Speed accuracy is an overloaded term that often is misunderstood. The meaning is often quite different depending on the time reference. Average rotational speed is the accuracy of the speed over a relatively long period of time. It's basically how close to 33.333 rpm does the platter turn. In my opinions this is a relatively unimportant measure. Small errors in pitch are quite inaudible but this number tends to be focused on. Far more important is speed accuracy within a very short time frame. In other words how constant is the speed as measured within a 1 millisecond window. Short term speed variations are easily heard and are detrimental to good sound. Yet there is no measurement available for this type of speed accuracy. Wow and flutter measurements are low bandwidth and completely miss these more important, higher frequency artifacts.
Every turntable in the world has speed inaccuracies. In my opinion nobody has reduced these into complete inaudibility. For most of these inaccuracies there is no measurement method available. Further I doubt that most could be measured.
On a direct drive where else could the measurement be taken? Besides measurements would be pretty meaningless anyway. Yes the Japanese DD tables from the 80's perfected the art to the point of having superb measurements. The sound is also respectable given the price point, but they are not even in the same ballpark as the current start of the art. I think that the DD topology is inherently superior, but as with all high end audio equipment the magic is in the implementation.
Speed accuracy is an overloaded term that often is misunderstood. The meaning is often quite different depending on the time reference. Average rotational speed is the accuracy of the speed over a relatively long period of time. It's basically how close to 33.333 rpm does the platter turn. In my opinions this is a relatively unimportant measure. Small errors in pitch are quite inaudible but this number tends to be focused on. Far more important is speed accuracy within a very short time frame. In other words how constant is the speed as measured within a 1 millisecond window. Short term speed variations are easily heard and are detrimental to good sound. Yet there is no measurement available for this type of speed accuracy. Wow and flutter measurements are low bandwidth and completely miss these more important, higher frequency artifacts.
Every turntable in the world has speed inaccuracies. In my opinion nobody has reduced these into complete inaudibility. For most of these inaccuracies there is no measurement method available. Further I doubt that most could be measured.