Tonearm mount on the plinth or on Pillar ?

Raul's tongue and cheek is on the money.  The variables are endless.  Drives, motors, materials, size , shape, weight etc etc etc...

What would be nice is someone with 1st hand experience with a table that has a arm attached and a pod that can go on other side.  Of course it would have to same arm, wire, cart etc.  Of course one might find that one cart might like it one way while another the opposite.  Then if one finds a difference now the subjective equation comes into play!!!

What would also be nice if a person with some real physics background in vibration and frequencies  would chime in. My quess in regards to the connection issue moving the pod around would be, I can not imagine a cantilever, at 2.5 grams, moving a 30lb plater or a 5/10 lb pod.  In regards to pod overall movement build a jig  to get close and dial it in with the overhang.

I do not have a dog in this fight.  I do have two tables and 4 arms.  3 pods and 1 plinth attachment.  Can interchange almost everything between them.  Have two diy tonearm, which are very close, so before it is over will do like I stated above ,one on plinth one on pod same table etc.

Enjoy the ride
Tom

This statement is unexpected and seems counterintuitive, at least to me. Could you describe the tables measured? If you've seen photos of Halcro's TT101, do any of the measured tables reflect that level of isolation?

Could you please list all the tables, arms and cartridges and what they were sitting on Atmasphere? Photos would be good here.
And can you upload the frequency print-outs for each one?

Good that for you it's easy task. I think that your measure is not exactly what happens during playback because you did not use a recorded LP and we want to know what it's happening during playback in real day by day listening conditions.

Now,: speakers playing loudly?.  95 db, 90 dbs, 100 dbs?  why only playing loudly?  We need to have information as day by day real as we can not over diferent conditions.

We ran this experiment using our lathe. The reason was we wanted to install a 12" Triplanar on the machine so we would not have to move the lacquer to a different turntable once in place- to test, simply place the tonearm on the cut.

The easy way out was to install the arm on a pillar. We found out really quick that was not the best move. Now you have to understand several things here- first, the lathe is mounted on an anti-vibration platform that is rather massive, designed specifically for the lathe. That in turn sits on a custom table with adjustable points for feet. The entire arrangement has to be by definition rather dead, else sounds in the environment can affect the cut. What we discovered is that the arm mounted on the pillar was giving us more noise than the same lacquer played back on a Technics 1200 sitting nearby.

IOW, it was not suitable for actually telling if our cut was truly silent, set up in this fashion.

By coupling the arm directly to the plinth in which the platter bearings reside the issue was solved. Apparently even though a very effective anti-vibration platform was in use, it could not prevent the arm from moving in a different plane from that of  the platter (which is the failing of pillars generally speaking, per my first post above, should anyone care to understand the engineering principle in layman's language). This ultimately required that we machine an arm mount that mounted to the plinth rather than the platform. We made our measurements using the phono equalizer in a Tascam mixer board, read by an Tektronics 465 oscilloscope. I hope this gives you some idea of how easy it is to measure this!

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. 

Now I understand this is bad news for some and as a result there will be those that think that somehow these principles don't apply to their machine. It is true that I did not make the measurements on anything other than our lathe, but if you think the engineering principle is somehow different, or that the lathe is somehow noisier than a conventional turntable (while at the same time somehow perfectly capable of turning out cuts that are so quiet that essentially the playback electronics are the noise floor no matter how quiet) you would be mistaken, check with Mr. Occam on that one.

It is of no consequence whatsoever that we used a silent groove for this test. A groove with modulation will still experience the same noise and colorations if the arm is anchored to a point that is able to move with respect to the platter.

This is not a difficult principle to understand; IMO the resistance to it springs out of the cost of some of the machines guilty of this engineering flaw- its an inconvenient truth (especially when you consider how much harder it is to make a plinth for the platter and the arm).  FWIW, the lathe is not a cheap machine either; if we were to put it up for sale in its present state (functional tested used stereo cutting system) it would be going for over $30K. If it were new it would be pushing 6 figures. Out of necessity it has far more precision in its construction than most turntables.

Now I want to make something very clear. I'm not saying a system with a separate pillar can't sound **good**. What I am saying is that if the arm mount is integrated into the plinth it will be lower noise and have less coloration, i.e. it will sound **better**.

I'm not sure that the cutting process tests can be transposed to the playback field.
After all.....you use direct drive and linear-tracking arm in the cutting process but you prefer to use belt-drive and pivoted arm for your playback.
Seems counter-intuitive to me......

Sorry Atmasphere,
I missed the point about the Triplanar and the Technics 1200.

I don't see how attaching the tonearm to the plinth can affect the 'noise'?
Surely the 'noise' is a function of the isolation, the tonearm pod mass, fixity, density and material selection as well as the tonearm rigidity.
There are some who are not fans of the Triplanar with regards to its performance in these areas.....but reaching conclusions about 'noise' when using different tonearms does not seem paticularly scientific nor conclusive.