Direct drive/rim drive/idler drive vs. belt drive?

I have to jump in here, perhaps a little late, but I have definitely enjoyed the banter. Especially the literary references; and I thought I was the only one who kept an unabridged Websters first edition at my reach. And what does my wife mean when she walks in the room and says "if you spent a third of the time you spend on this stereo stuff on our rlationship things would be better". This reminds me of a line from a poem I like "If you can keep your head when all about you are losing thiers and blaming it on you"
Back to the topic:
Question #1- Is the torque(twisting force)acheived by the platter dependent solely(sp) on it's driving force, or does it at some point become a product of it's rotating mass?
#2 If the bearing matches the mass of the platter, no matter how great (e.g. the fan blade on a jet engine), are the problems brought up about bearings solved?
#3 I believe the Feikert Twin TT uses a kevlar belt. Not much stretch there. If the belt is for all practical puposes stretchless, does it become a direct drive?

Thank you all for your responses, I appreciate the time you put in this, even if my wife doesn't.

Matt

HI Matt,

I can't help with the technical questions. I will offer this. My wife and I decided to stop "working" on our relationship after the first three years. That's when my first son came along. After that we just "worked" on making it through the day. It will be 34 years this winter. :-)

Mark,

I think you'll be surprised at what can be achieved with standard AC motors and belts even less compliant than your Mylar when the drive mechanics are understood.

If it isn't giving anything away, how is the filtering by the belt done differently with less compliance in the AC approach? Or am I confused by my own assumptions?

"Similarly if a manufacturer sends me several samples of a high cost three phase motor and says "do your best then bill me" the results can be pretty good."

I resemble that remark. Yuk. Yuk. ;)

I do have a habit of sending motors to Mark, and leaving the task open-ended. It can result in sticker shock, but the result can be stellar.

An external rotor three-phase eddy current motor that has has a 90W draw can be very inefficient, but the payback is in extreme smoothness, and also wonderful dynamics. So, I agree with others that a decent motor is key to high performance. In the case of Saskia, my turntable, the platter gains equivalent mass from this approach, too. The external rotor provides this to a point that when used with an idler it is the equal of a belt drive that has a platter that weighs several hundred pounds. The motor counts for a lot, but the platter can be further tuned to enhance inertia even more. Then, there is the spindle, bearing well and associated parts which also play important roles when it comes to ruble control, dynamic braking, evenness of play, etc. Again, if any aspect is neglected, performance suffers in one way or another.

Win

I've been working with a modified form of the old Empire table for some years now. It has a very powerful motor that has a lot of torque, runs at high speed and has a lot of flywheel action. Years ago I ran an electronics service center- while there I service all sorts of tables including the Technics Sl-1100, the SL1200 and the SP-10.

It is my opinion that the drive does not matter as long as it is robust and executed well. Weak drives just don't seem to do it and I have seen very little in the way of servo-controlled belt drives with weak motors that work right.

However, to my ear the platter pad has a far more profound artifact than the drive! Years ago I was lucky enough to obtain a platter pad that was truly neutral- and use it on a variety of 'tables. With it, the SP-10 sounds identical to a stock Empire and any number of older Pioneer belt drives (the platter pad is heavy so 'table needs a robust bearing to support it).

Without maintaining the platter pad's contribution in audition of all these drive systems, a huge variable is introduced that IMO/IME makes it impossible to ascribe a difference properly. The platter pad should reduce resonance in the platter; IOW the resonant signature of the resultant platter cannot be ignored!

Now it might be that someone here has been this careful- has anyone in auditioning all these different tables (Lenco, Technics, Garrard, Micro Seki for example) been able to keep the resonant signature of the various platters constant, as well as the durometer of the platter pad surfaces? If yes- differences might be ascribed to drive. If no- differences are probably not the drive at all, but the platter's resonant signature as the vibrations in the groove are decoded.

What I am saying here is that the needle playing the LP makes a physical sound and vibration that the LP itself reacts to. If the platter does not control that, you have a coloration. IMO/IME, 95% of table differences are this effect.