Albert Porters after market panzerholz plinths

One more thing I can note from my experience with DD and belt tables years ago is that overall DD tables did indicate better speed control overall than belts. Belt drives tended to have greater variability in speed accuracy from unit to unit as indicated by strobes, however, the better belt drives measured similar to DD tables in this regard. Often belts would have dirt or otehr deposits on them which caused slippage and measurable speed variations, even with new out of the box japanese tables of the day. Usually, cleaning of the belt in otherwise good condition with light solvent would remedy the problem. I was most diligent about checking this aspect of a belt drive table before turning over to a customer. Also most belts do wear over time and that results in similar slippage and speed variations as indicated by strobe and the remedy here is to replace the belt.

I have no data on longevity of DD tables in regards to speed accuracy in comparison to belts so I cannot comment on whether one or the other offers greater stability over the long term. I suspect good DDs may have an advantage here however if there is a problem the remedy to fix would be more costly than a belt replacement.

Also, DD tables are clearly more robust and suited for DJ use in that these tables are transported frequently and belt drive tables are not well suited to be transported continuously without additional preparation I suspect.

I made no comparison between direct- and belt-drive turntables on any level, especially to say one is noisier than the other. I was just addressing what I perceived to be an inference by Mapman that direct-drive turntables are inherently noisy, because of the positioning of the motor. Nor does it follow that because a DD turntable might (or might not, according to Raul) sound best in a massive plinth, this is an indication that DD tables have special issues with noise. To me the rationale for the massive plinth is the high torque of DD motors in the more expensive tables. This torque is applied at the center of mass of the platter and so is best counter-acted by a massive plinth. Earlier I made mention of Newton's third law of motion. The acceleration of the platter by the motor is exactly counter-acted by a force to twist the motor/chassis. If we firmly fix the motor/chassis in a massive plinth, then the angular acceleration on the motor/chassis goes down in proportion (In a linear system, F = ma; where m = mass and a = acceleration. If m goes up, a goes down.) Thus vibrational forces induced by the very torque of the motor (not by noise per se) is diminished. This is the way I think of it.

Dear Mapman: Speed accuracy and speed stability is IMHO a critical main target in any TT design but seems to me that in the best TT set ups ( either drive mechanism. ) that is not any more an issue, I can be wrong but that's what I think.

What I don't know for sure because I never measure it is that if my vintage BD and DD TTs are right on original specs as my today TT designs ( that I assume are on target in this regard. ).
All in all I don't heard/precieve any trouble with my units regarding speed accuracy or stability.

Regarding DJ the main problem is that DJ's needs heavy torque ( at any " moment " ) with the TT and very fast start/stop TT characteristics and I don't know yet any BD that can meet DJ needs job.

regards and enjoy the music,
Raul.

I'm still not getting it.

I believe a table spinning at a constant speed has 0 acceleration. Acceleration occurs as the table gets up to speed and prior to playing. So I'm not sure I understand how the higher mass plinth can enter into this. If teh plinth does not move or rotate during playing at target speed, then it should be fine I would think.

Also my understanding of the panzerholz material used in aLBERTS plinths is that it is very rigid but lower mass than comparable standard wood materials, so I'm not sure that adds up either.

I could see the value of the plinth using that material in theory again if the intent is to isolate from vibrations from the motor or perhaps even otherwise. No doubt any kind of motor used to drive a table produces vibrations, so perhaps the tonic is in teh specific cases where this is an issue otherwise, though I am skeptical it is an issue common to all tables in particular those already designed out of the can to deal with the issue.

I will also add that I cannot imagine a case where applying a more massive plinth properly can hurt, and they are very nice looking for sure!

Mapman, You are quite right that not all that torque is used during play. We like to think that some torque now and then is needed to maintain speed stability in the face of stylus drag, which can vary in degree related to the tortuosity of the record groove. Torque is also in play when the platter goes off speed for any other reason, like due to cogging, etc. I never saw anyone put any numbers on these forces, so I don't know how great or small they may be. If we ever had any real facts to go on, we would not need to have these rambling discussions.