Turnable Rack Vibration

I think most folks are unclear about TT isolation/absorbtion. Things like spikes, roller blocks, Stillpoints, iso-platforms, etc. will drain away vibrations created by the TT mechanism (and I suppose the cartridge itself ;--) but these values should are hardly even measurable. Certainly not if the TT has decent bearings and motor drive. Vibes in the actual vinyl record created by the stylus should be damped by the platter (mats and/or clamps are what you want for that.) Vibes and impulse energy coming TOWARD the TT (like from foot falls, or bouncy or resonanating floors) are VERY hard to stop and here's why:

First these vibes come in all different frequencies and no one material --springs, sorbothane, hydraulic damping feet, rubber bands (like on the SME) -- can block them all. In fact, some of them can do more harm than good if they happen to naturally oscillate at one of the incoming frequencies!

And second, any mechanism that would have a low enough resonant frequency would have to be so big as to be impractical in a home environment. Just look, for example, at those HUGE spring frames in which they suspend (relatively small) microphones in recording studios. Can you imagine a turntable-sized contraption!?

That's why we have wall shelves ;--) I have seen a few audiophiles construct concrete block piers, or pillars, filled with sand, right on top of conrete slab floors in their listening space(s). However, it does require an extraordinary commitment to the location, ha, ha!
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All very good points, Ns. The wall mount is the easiest, most effective (for the price) solution. I considered it worth a try in Neil's situation, first without the wall-mount. I have seen this method used on top of racks and table supports that were located on the floor. The supplier of the information insisted the isolation was effective. I know only that with my installation, the results have been superb, the arm and plinth drain into the Brightstar, and the springs isolate the table. The wall mount is however, a major contributor to its sucess.

My judgement is that it is worth a try, not much cost involved, and may be retained and used in the final solution.

Regards,
Dan

I guess my point is that any top-of-shelf/under-TT treatments, if they appear to work, do so because you already have a rock solid floor, and a rock solid rack (like a Billy Bags TT stand.) But if you have a bouncy floor, it's just going to take the rack and all that other stuff with it.

To me, a solid floor is everything, and when the floor can't provide it, then you need a wall shelf (and hope and pray that the wall doesn't vibrate!)

A lot of good comments, but one is missing, so I will add it. Acoustic shield around the table. The sound engery that is in the room will directly impact the table, arm and cartridge. Play some music in the room from a different source and put your finger on the pith, arm and cartridge. You are bound to feel the vibration the acoustic engery that is flowing all over the TT. Just think what is happening when you are actually playing a record, the speakers vibrate via acoustic engery everything. In the interest of full disclosue, I am in the process of marketing 'acoshield', the solution to fixing this problem.

Thanks for all the great responses.
Buconero117: I am fortunate that the turntable is in a closet so in room vibrations, especially airborne are probably less of an issue
Nsgarch: I whole heartedly agree with you in regards to wall mounted tables. The change from going from the Target shelf to the rack is the source of all this heartache. If i was not so stubborn i would remount the wall shelf in a second. As it is i am going to try to work through the rack positioning to hear if i can improve anything. My strategy is to position the TT on the granite slab which in itself is mounted on 4 isopads placed on the top shelf of the rack.
I know from experience that increasing the mass on the top shelf of a structure / rack helps to dampen lateral forces.
I will report back once i have given it a try