Tonearm mount on the plinth or on Pillar ?

I propose that Ralph be enrolled on the calendar of saints. His restraint is supernatural - a miracle thrice renewed!!

**As to sound pressure- we get about 90-95db of noise going on when mastering. The vacuum system is enclosed in its own chamber, but still makes noise when in operation.**

That's a direct quote. Now we learn the motor is at the end of a long hose. Does it produce 90-95dB of noise in room?  If so, is this noise + mechanical vibrations? 

The measurements are based on this story and now it looks inappropriate. This is the same as the music coming off a turntable?

Looks like we have no relevant measurements.

fleib

True, a suspended-subchassis table will always have a plinth common to the platter bearing and arm pillar (at least as far as I know!), while a non-suspended doesn't have to, the later fact the impetus for this discussion. When I was said I would not consider a table without a common plinth, that included non-suspended tables, which I agree with the others is, in regards to the importance of the mechanical integrity between platter bearing and arm, no different than a suspended-subchassis design. How that plinth is isolated from what is below it (by springs---commonly---in suspended tables, and whatever method in non-suspended) is a related but separate issue. But the "correctness" and superiority of a common plinth turntable design does presume the plinth provides an inherently rigid mechanical connection between platter bearing and arm pillar simply by virtue of it being common, too large a presumption as well as an over-simplification, I realize in hindsight. The rigidity of the plinth in different tables varies, and is a major contributor to the sound of every table. Their designers have invested a lot of time, effort, and money into either maximizing the rigidity of the plinth, or at least strengthening the mechanical connection between platter bearing and arm pillar.

My table was designed with this matter a very high priority, it's non-suspended plinth made of steel in the shape of a shallow upside-down baking pan, and filled with plaster of Paris, to make it much stiffer and more non-resonant than the common MDF, acrylic, or aluminum (or combination of two or all three materials) plinth. Recognize it? But the designer of this table took his intention and dedication to making the mechanical nature of his deck as stiff as possible to another level by addressing the other area of mechanical integrity in turntable/arm/pickup design, the front end of the arm. Free to vibrate (how much and at what frequencies dependent on the stiffness and resonant characteristics of the headshell, arm tube, all the way back to the arm's bearings and counterweight, and down into the main pillar), it will and does! When the end of the arm, and therefore the cartridge, the measuring device of the LP groove, is free to vibrate and resonate (especially cartridges employing low-compliance stylus'), it is surely adding to or subtracting from the output of the cartridge. That is a major source of lost or added information in the playing of an LP, and only one table in the world addresses the issue. Now do you recognize the table?! ;-)

Lew,

**To wit, there would be a great deal of movement of the LP surface, mediated by the suspension, that could not be followed by movement of the tonearm pivot, and this would generate spurious signals at the cartridge/LP interface. On a more micro level, this principle is operative in the relationship between any plinth, suspended or not, and any arm mounting system.**

Not true. On a micro level the vibrations would not make it between platter and arm with a high mass "dead" plinth. Part of the reason such plinths sound good is because they resist vibration transmission.

You think this engineering principle holds true under any circumstance. It does not. It holds true if and only if part of the table is in extraneous motion and the other parts move with it simultaneously. That is motion other than normal platter rotation. High mass tables are more likely to be immune to such motion.

**Reed used to make an armpod.
 
I believe Nandric (Nikola) had the first one ever made by Vidmantas. I was looking for the resonance research data that was prominently displayed on his website, which showed a visual of the different resonances and their paths (integrated versus isolated parts). The info had a lot of cool lines and colors differentiating the two, with information clearly supporting the armpod.**

Regards, 

The platter and arm must move in the same plane and frequency, should there be any movement at all. Likely this would be airborne induced.