Is Direct Drive Really Better?

John

"The torque, as in stored energy/moment of inertia, is not sufficient to combat stylus force drag, it takes an active motor force to push the platter through the dramatically-cut grooves and the variable stylus force drag they cause: it will still slow, the belt stretch, and then contract, albeit more slowly as it has to drag so much mass, and the motors used in belt-drives are insufficient to push the LP through and keep the speed rock-steady. "

Now re-read Rushton's post. If stylus drag is really capable of slowing an 80lb platter how could the walker continue to play with the belt cut for tens of seconds ?

Can people not see the equivalence of torque by stored inertia and torque by electrical energy (motor) ?

Again, I'm perfectly open minded when it comes to purchasing, but those who decry belt drive must first give some reasoned argument as to how a low torque, massive platter design is supposed to be slowed by a minute diamond dragging through a groove with a tracking weight of only a few gramms.

Interesting comment, Drubin. However, it could be that CD does kick butt in the area of speed stability but loses out on other aspects of continuity due to "bits is bits" fragmentation. You can't grind steak into hamburger and then make steak again no matter how constant the speed of the grinder or the ungrinder.

Hey Sean.

"Can people not see the equivalence of torque by stored inertia and torque by electrical energy (motor) ?"

No they cannot as they do not want to. If you look at the actors on this thread you will see they reappear numerous times on other threads bashing belt drive TT. I have posted questions like yours in the past and never got a coherent or sensible response.

A poster in this thread managed to name 4 DD TT which were reputedly good (note reputedly) and then went on to say that since a SL1200 is such a good seller that "these things point toward a degree of superiority". When I read that I gracefully declined to continue further conversation.

This simply yet another example of folks confusing consensus of opinion with facts. Sadly this is quite prevalent amongst audio folks.

As a hobbyist/DIY-er myself, I fully understand (and have empathy for) their passion for their idler wheel and/or DD turntables, so I will take no pleasure in bursting their little bubbles.

Regards
Paul

The universality of torque aside, Walker's cut-belt demonstration was a bit of circus stunt. Of course the pitch and tempo of the record dropped during the 20 seconds -- that's a fact of nature -- it just did so slowly and not very much, so nobody noticed through their surprise. If they didn't notice that, then they didn't notice whatever effects of dynamic stylus drag were superimposed on that -- not only because of shock and awe, but because there was no reason for those effects to have changed much before and after the cutting of the belt. The massively heavy platter minimized those effects before the belt was cut, not the motor, and removing power didn't change that. Whatever dynamic speed modulation by the stylus sounds like, it couldn't be a gross effect, it probably manifests as a subtle alteration of textures or something, maybe a bit of clouding of the soundstage, who knows. Hell, there are ways in which you could predict *any* turntable would sound *better* without its motor interfering, if only they all could keep spinning away like the Walker. (Maybe cutting the damn belt even granted it some of the virtues of direct-drive for a time ;^) Point is, there was never any question that an 80lb. platter on an air bearing for $20K+ could help overcome dynamic stylus drag, the real question is if that's the only way, or even the best way. (I've always assumed the really massive platter jobs must have very low flutter but rather high albeit long-period wow, and maybe that's a smart tradeoff.) Or if any of that matters to the sound nearly as much as the resonant characteristics of the turntable -- if not, then use any drive method, just make sure the thing has good vibrations.

"You can't grind steak into hamburger and then make steak again no matter how constant the speed of the grinder or the ungrinder."

Actually (in theory) you can. A sampled waveform, sampled at a frequency of at least twice that of the highest frequency in the waveform, that is reconstructed with a sin(x)/x filter will perfectly reconstruct its original signal. Once again theory says that digital can produce perfect sound. The problems are in the implementation.