Is Direct Drive Really Better?

Dear Jean: Thx about the Scully info.

+++++ " The best way to determine speed stability given the problem of which measurements are meaningful, is the human ear. " +++++

The question is: in what range of pitch sensitivity is our ear? how much/less changes on " pitch " can we hear ?

About the statement of Mr. von Recklinghausen, today things are changong about. Today we have better audio designs, better audio parts, better " rooms ", improved know-how, etc, etc. , at least at the high-end audio niche.

Regards and enjoy the music.
Raul.

The Technics quartz locked lathe is the standard.

Tbg...If you want to measure resonant frequency (and I presume Q) there is a straightforward way to do this. You apply vibration to the item you are testing, with frequency swept over the range of interest, and record vibration amplitude of the item under test using one or more accelerometers glued to the item at locations of interest.

You might want to perform such a test during development of the design so as to achieve a non-resonant platter.

O.K. Everyone seems to agree that we don't like vibrations and everyone seems to believe that speed stability is of great importance. The only diagreement I've heard has to do with which is more important. Doesn't it seem that bringing them both to manageable levels concurrently should be well within reach given what has already been accomplished?
Likewise it would seem that all of these 3 drive systems are capable of performance levels approaching perfection. So there are three best approaches and none are inherently inferior. Is anyone going to switch as a result of reading or participating in this thread?

Direct drive or die.