Turntable upgrade recommendations: SME vs AMG vs Technics vs other

Here is a bad thing about a spring-suspended DD turntable: The energy put into rotation of the platter is also going to twist the chassis on its suspension, in the direction opposite to platter rotation (counter-clockwise). That is why it’s a good thing the Motus uses a low torque motor. Even so, the platter might end up with a very inconstant speed, due to the servo trying to correct for twisting combined with the variable effects of stylus drag on the rotation of the platter. Has anyone published a study of the speed constancy of the Motus? I am all for isolating TTs, but not with springs. As to low torque vs high torque (without defining the terms, the two statements are meaningless), torque only comes into play when the platter is starting up from rest. Once the platter is rotating at or near its set speed, torque is neither a good nor a bad thing, so long as there is enough to tweak the platter speed when called upon by the servo. What does make a difference is the "tightness" of the servo control. Different designers have adopted different levels of stringency for speed control. Technics TTs historically (I don’t know about the SP10R) adopted a very tight feedback. Other vintage DD turntables used looser servo control, especially those that also used coreless motors, like the L07D, the Pioneer Exclusive, and the Yamaha GT2000(X).

Mijostyn, Your categorical dismissal of the Lenco is silly. True, the bone stock OEM Lenco GL75 or 78 can be bested by modern turntables, but not by any belt driven turntable below the $2500 or so retail cost, provided only that the tonearm is refurbished or replaced by a better one, and highly modified Lencos that still retain the motor and the vertical idler drive mechanism would surprise you, if you ever sought out a sample to listen to. Visit Lenco Heaven to learn what can be done on a relatively limited budget with Lenco parts.

Something that Raul wrote that wasn’t "wrong" has been misinterpreted by subsequent comments. More mass per se does not result in a higher resonant frequency; it’s just the opposite. I think what Raul meant is that more platter mass on an air suspended turntable requires more work by the air suspension which could result in an increase in the absolute magnitude of the resonance. I don’t know if that’s been proven, but it makes some sense.

@lewm 

Agree with almost everything. But: a low torque motor (e.g. 2W - yeah, I know watts are joules/sec) simply lacks the torque to affect speed very much. It's barely enough to overcome stylus friction and belt flexion, so it's tiny irregular forces (noise) have little influence on a massive platter.

You note that 'tightness' of the servo is an issue. I do so agree. That's why I use an AC motor - an AC motor sets a constant pace, it doesn't try to correct the pace. The speed of an AC motor can be set very accurately and very stably with a quality power supply.

This is why I like Rega tables - extremely light platters/plinths/arms with low torque needs and noise. Great arms, build quality and durability. As long as you isolate them, they are a tremendous value.

By the way, when I put mine on a spring platform from Townshend the sound improvement was shocking. Now, it caused foot falls (so @lewm your concerns about springs are on the money even though @millercarbon will strenuously object to that comment) because of the frequency combination, so I had to put it on a wall shelf, which got rid of the problem, but you have to be sure the springs are the right tension for optimal sound improvement. The sound is dead quiet and the speed is at 33.28 and 44.98 RPM respectively and probably is even a little more accurate as I measured the revolutions with a cell phone which added a little weight to the platter.

Not sure why they don't get more positive mentions on the 'Gon.

terry, But you want the motor to affect speed, when the speed drifts away from constancy. So, in your first paragraph, are you making a virtue or a problem out of "torque".  I am not sure what you meant.  Could be you are saying that to couple a low torque motor with a heavy platter is a good thing, because speed in such a design is primarily maintained by the rotational inertia of the heavy platter.  That idea has its advocates and its detractors, as well.  What is remarkable is that so many different seemingly conflicting design philosophies can be made to "work" such that the end users come to swear by this or that approach.

@sokogear 

Yes, I appreciate my Rega P8, but you're right, Rega doesn't get any respect in the audiophile community.  Maybe there's some valid rationale for that, as they don't subscribe to either major turntable paradigms:  mass or suspension.  I am very happy with my Rega P8, but it would be interesting to compare to a "higher quality" turntable to flesh out the differences:  strengths and weaknesses, etc.

@rauliruegas 

Yes, the FM223 is apparently in very high demand, and it is quite expensive, at about 3 x the price of the standard Ypsilon phono stage or 1.5 x the price of the SE version.  I would imagine that the FM223 would be worth it, but for me that would be like going from a base Mercedes to a top of the line Bugatti -- perhaps I need to go to the upper level Porsche first? (less expensive than the Bugatti, but more performance than the Mercedes).