Next step in Turntable

@chakster, it is very simple. If it does not bounce between 1 and 3 Hz it is not isolated and the amount of noise passed on by the environment is easy to see. Hook the output of your phono stage to an oscilloscope and put your stylus down on a record with the turntable stopped. Tap on your granite rack and watch the oscilloscope jump. All that wiggling going on in the background is environmental rumble. On any good suspended turntable you will not see any of it. The tracing won't be dead quiet as the cartridge is capable of picking up air currents in the room.  You can pick up an interstate highway up to a mile away depending on surface conditions. Have the wife turn on your dryer, watch the oscilloscope jump. Same for every mechanical device in the house. 
These are the only feet I have seen that represent a very intelligent design concept.https://upscaleaudio.com/collections/vibration-control/products/solid-tech-feet-of-silence   Assuming the spring rates can be specified for the weight of the turntable they should work fine and be very stable. Pricey but, if you have an unsuspended table you like, these would be a reasonable add on.

I use Solid Tech Feet of Silence, they have proved to be the most effective feet in my System when combined in the assembly along with my my Differing Tiers of Construction, that are used to produce a Presentation that is very satisfying to my Personal Preferences.
These are the Footers that are in direct contact with the TT's Plinth, and also the Footers that  have superseded all my Previous Methods.   

@mijostyn

If it does not bounce between 1 and 3 Hz it is not isolated and the amount of noise passed on by the environment is easy to see. Hook the output of your phono stage to an oscilloscope and put your stylus down on a record with the turntable stopped. Tap on your granite rack and watch the oscilloscope jump. All that wiggling going on in the background is environmental rumble. On any good suspended turntable you will not see any of it. The tracing won’t be dead quiet as the cartridge is capable of picking up air currents in the room.

I don’t care about noise I can’t hear! 1 - 3Hz ???

When I play record there is nothing under 20Hz and I don’t hammer my turntable when I listen to the music. I should concern only about frequency range comming from the speakers withing vinyl record frequency range, the speakers are near. I have absorbers and diffusers on the walls and ceiling in my listening room.

Sitting in Russia and listening to my favorite vinyl I don’t care about seismic vibration from Japan, aliens rarely use their weapon in my area since the Tunguska event in 1908, we are fine. I don’t have to glue some springs to my slippers before I come to flip the record.


Audio-Technica AT616 Pneumatic insurator are super effective in 50Hz - 20kHz range. Pneumatic is super effective at 200Hz. Overall they are effective at 20Hz - 50kHz and there are graphics of the measurements in the manual. They are also level adjustable and ideal for some turntable plinth! I liked them under wooden plinth of Technics SP-10mk2, Denon DP-80, Victor TT-101 (because stock feet sucks) ... I the AT/616 under my huge Tannoy “15 DMT MK2 monitors on the front side only (to change the attack angle).


Regarding other turntables I want to remind you again that Luxman PD-444 is suspended on its stock level adjustable feet. I don’t use AT-616 under my Lux PD-444 turntables, because this plinth is a perfect design, But I use custom racks (they are metal filled with sand).

As said my Solid Tech Feet of Silence have superseded all other used footers.
My AT 616 are used under a Sub Plinth and are no longer used to be the Footer that is in contact with the TT's Plinth.
The Feet of Silence when used in the Construction of Materials to support the plinth has bettered them, when my ears are used to assess the effects.
I do use AT 616 under Cabinet Speakers and the effect that they have is quite satisfactory and I see no reason to change this as a method.

No fancy measurements at my end to convince me of my decisions for the use of Footers, The Method used is to Buy, Trial, Trial, Trial, in various permutations, Keep or Discard, using my ears as the Tool to make the choices.
When the Footers referred to above are under the radar, the purchase costs do creep upwards to be able to assess such devices. 

As difficult to believe as it is, even for myself when first experienced,
my Home Built Aerated Suspension Sub Sub Plinth was to have an effect on the above Tiers in the Support Structure, that really allowed the TT's Presentation to be quite special, and showed the real difference between the AT 616 and Solid Tech's     

The problem with @mijostyn is that he never tried the AT-616.
Here is the image of my AT-616 in my system (under Tannoy).

This is another set of AT under my ex SP-10mk2.
4 x AT616 designed for up to 132 lbs weight (60kg).  

The problem with Solid Tech is their ugly design, I would never put them under anything like vintage turntable (but it’s just my opinion).