Pros and Cons of Platter Mass

I hope this doesn't qualify as a freak argument, but I believe the ideal turntable platter would be close to no platter at all (the low mass concept taken to an extreme). The platter serves only two purposes, first it provides a place for the disc to sit and second to impart the motion of the motor to the disc. Neither of these functions requires high mass. The functions that Jameswei attributes to the platter should actually be performed by the motor. To the best of my knowledge only two turntables have been designed along these principles - one by Ed Meitner and another out of England by Real Sound. I've heard neither of these turntables so I no idea about the quality of the implementation. I suspect the reason that there are so few turntables designed with minimal platters is the lack of suitable motors. Motors designed from the ground up to properly perform what a turntable motor is supposed to do and not rely upon the platter to correct for its failings.
Notwithstanding the above, I have an RPM turntable with a relatively high mass platter.

Onhwy61. In an ideal world, your ideal zero mass platter would be great. In the real world mass is required to smooth out the energy drain from the stylus retrieving heavily modulated passages from the vinyl.

The motor you propose would have to not only turn at exactly the correct speed, it would have to recover in microseconds to any variation in drag coefficient or velocity changes. This might be possible, but for the present time, a heavy platter turned by a belt to isolate the less than perfect motor is the best we have. Much like the designers decided on for your RPM.

Albertporter makes solid sense and as a practical matter a high mass platter is the way to go. On the impractical side, it's interesting to note that Andy Payor's Rockport turntable uses a direct drive motor that is capable of speed accuracy in the microsecond range. The motor utilizes extensive microprocessor controlled speed correction and is reputed to cost $15,000. Payor mates it with a high mass platter.

I agree with the above comments, but would add that as with most things, there are no absolutes. The correct amount of mass within the context of the other design characteristics of the turntable, and ultimately the entire analog playback system is most important. In my experience, and based on my tastes and priorities, the turntables that let me get closer to the music, as they say, have been of the high mass platter type. But that is because to me, the weightier, denser, and more harmonically natural sound that heavier mass tables, as a class, seem to have is more important than the little extra bit of liveliness that the lighter mass platter turntables seem to have, as a class; sometimes at the apparent sacrifice of a little tonal richness. There really is something to the "the Linn gets your toe tapping" stuff. To my ears, there are times when recorded music needs to move very very quickly to really get close to achieving the "aliveness" of the real thing; and some tables, particularly the Linn types, allow that better than others. Some say that it is the resonances or ringing(distortion) that a table like the Linn has that gives that illusion, maybe, but I do know that many big mass tables that I have heard can sound a little like the music is a bit too under control; not expressive enough. I often miss the excitement that I hear in a table like the Linn. In fact, a Linn is probably my next major audio purchase. The idea of owning and keeping two turtables in the year 2002 makes me chuckle. I have experience with AR, Technics, Ariston, Rega, Linn, Well Tempered, Forsell, and VPI (which I own), and have heard Goldmund, Basis, Kuzma, Roksan, Meitner and others; I suspect that there are tables that I have not heard that strike a balance between these two major considerations.

By the way, I heard the Meitner at the first Stereophile show in NY, and unfortunately was not impressed. I still remember that it was one of my least favorite demos. With Acoustats and Meitner electronics there was very obvious wow; I remember being very surprised that the hosts would find that acceptable. The absence of a platter for the record to push against and thus flatten itself out, at least in part, made the playback of anything but perfectly flat records unacceptable IMO; the pitch fluctuations in the music were ridiculous. Imagine negating the benefits of clamping; it just did not work IMO.

Still nothing like vinyl.

Best

Looks like my physics class paid off. I thought there might be more implications of platter mass than I initially theorized with before starting this thread, although Frogman's (great moniker) comment on aliveness and resonance was new to me. And due to the number of low mass turntables, I also thought the responses would have been a little less one-sided. I am immaturely happy with the responses as my TT is a high mass design (and less expensive than many low mass ones). Thank you everyone.