Vintage DD turntables. Are we living dangerously?

For a long time I agreed that the tonearm and the platter should resonate in unison to avoid added distortion. But after reading about good results from the separte armpod approach, I started to question my original thinking. I realized the tightly coupled arm to platter approach would work only if the stylus is also tightly coupled to the arm, that is, extremely low or no compliance at all. But most cantilevers are attached to a piece of compliant rubber and that automatically decouples the stylus from the rest of the arm so the separate armpod becomes really inconsequential and therefore it's not surprising that it can sound good reported by those users. That's just my current thinking and I'm open to other possibilities.


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Fkeib. I agree, 100% torque conversion is not possible.

That is why I listed this assumption..."TDs motor only provides enough torque to maintain original speed before stylus is lowered, after it is lowered."
I have assumed that the motor plays no part in dealing with stylus drag. It is only delivering enough torque to overcome windage and bearing friction.
Any additional friction in the form of stylus drag is resisted by the stored energy in the rotating platter. That is why I needed to calculate its moment of inertia.
This makes my calcs conservative, since there will be some restorative torque from the motor. Since we don't know how much, it was considered best to ignore this parameter.

The info I did find online relating to calculating stylus drag used a free wheeling platter, running at rated speed. Timed to stop without and then with the stylus lowered. My calcs are a derivative of that method.

I don't think that Maynard and I would agree on very much at all!

Lew,
I suspect a massive pod on spikes threaded into the bottom of the pod might be better than bolted to a base/shelf. I understand what you're saying, I don't think it's necessarily true.
**Whatever happens to the tonearm, from whatever source of spurious energy of any kind at all, should also "happen" to the platter/bearing at the same point in time.**

"Whatever" covers a lot of ground. Are you tracking through a seismic event, perhaps your dog bumped your TT stand? I chose sound pressure waves because it's the logical choice for a non-suspended table. In that case I think it might be better if the pod and platter were not joined at the hip. Spurious energy would more likely to be transmitted and propagated from one to the other by their common joining. This is a bad thing, not good.

Once again, having the platter, arm and motor moving in unison is the law of suspended tables. Even those with a fixed motor seem to get half decent results sometimes. Throw out the suspension and what specifically are you talking about with spurious energy? Why is it better having them joined? Methinks it's worse, with greater potential for degradation.
Regards,

We're not

Richardkrebs,
This is not a freewheeling platter running at speed. It's constrained by the string.
If you measure as suggested, I think you'll find zero movement of pod or platter.
Regards,