Albert Porters after market panzerholz plinths

Mapman, You have fallen prey to a common fallacy regarding direct-drive turntables, one that was first foisted on the audiophile public when we were led to believe that belt-drive is inherently superior. That is the idea that a direct-drive turntable would naturally be "noisy", because after all the motor is right there at the spindle/platter interface. But if you will take note of the actual manner in which all of the better direct-drive turntables are built, you will see this is a fallacy. Generally the magnet structure or stator of the motor is part of the platter itself or is firmly affixed to the platter when the platter is in place. Then the rotor part of the motor is a fixed non-mobile structure around the circumference of the magnet/stator. Thus when the platter is in motion there are zero moving parts separate from the platter; it is driven directly by the electromagnetic interaction of the stator and rotor. Only the bearing itself can contribute any noise into the system, just as it can also do in a BD or idler-drive. Moreover, the DD motor only has to rotate at 33.33 rpm, in contrast to the motor of a belt- or idler-drive turntable which has to rotate at many times the speed of the platter. Slower motors tend to be quieter than faster motors. As further evidence of this, all you have to do is look at the fantastic S/N ratios thus achieved by the best DD turntables. So, you are free to prefer whatever you prefer, but don't say that DD turntables are noisy per se.

I used to sell many belt, idler and direct drive tables back in their heyday and heard many. I could never attribute a clear sonic difference to drive type. Tonearms, carts, and other things but never drives. Nobody told me any type was superior. Strobe light speed indicators indicated that either drive done well could be equally accurate. I steered most customers to the belts in that DD tables cost more for no real benefit I could discern. I never sold any really good idlers, so I was not a fan of those at all.

These were my collective observations having been there and done many different tables. Granted, these were stock units and not the beefed up versions available today.

Either DD motor noise is an issue and the plinth the solution or not. I do not know for certain which but I don't think you can have both both be true. The plinth might still be helpful for external vibes, but as I alluded to above, there are other more effective ways to establish a solid foundation to isolate table from external vibes.

YEs, I am familiar with the fact that DD motors rotate more slowly and that in itself is an advantage (one of many any design can sport).

Dear Lewm: Maybe I'm wrong but I can't read where Mapman posted that DD TT are noisy per se.

Anyway I thinmk that the noise TT subject it is not a cue for real differences in TT drive mechanism performance.

If we take the best DD we can have noise figures like -96db in the SP-10MK3 ( it will be interesting to make a measure today in one sample of this TT. ) or around -100db like Rockport but there are good examples in the BD side with TT in the -90db values. I can't speak on this specific noise subject about idler drive TTs.

What for me is or could be interesting is not to know those " fantastic " values/specs but to know which is the TT noise threshold where there is no or where don't have any more influence in what the cartridge " takes ", where is that threshold TT noise figure/value where there is no more influence in the quality performance we are percieving.

Because: how can we sure that those -90db or -100 db or whatever are good enough?
This is something IMHO that belong to the TT designers as many other TT subjects/questions that today there are no clear and precise answers.

Regards and enjoy the music,
Raul.

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.