spring loaded platform non-suspended turntable

I have a Technics SP-10 mk2, 100 lbs. OMA slate plinth and a schroeder tonearm. Would using a spring loaded or air pressure vibration control platform such as Minus K or vibraplane negate the benefits of a direct drive non-suspended turntable?
I would suspect that a non- suspended Table can always benefit using some kind of spring or other loaded platform under it. I used a similar under a well-tempered many moons ago with nice results. I would say yes to your proposal, so go for it.
Crubio, I'm not an engineer but I'll suggest you need to consider three conditions. One is acoustic vibration from your listening room environment. For example, where is your turntable placed relative to room node build-ups? Hint: avoid placement in any corner, bass range build-up is greatest in those.

Next are the mechanical vibrations generated by the table itself. Slate has a good reputation for absorbing (draining) low frequency vibrations so that, along with your 100 pound mass, should do well in minimizing this problem.

Last are the external mechanical vibrations which can affect your turntable/arm/cartridge performance. This will vary from set up to set up. Do you live near a street/highway with heavy traffic? What is the construction of your floor? What kind of stand is your table mounted on? Is it mounted on a shelf attached to a load-bearing wall?

Depending on your conditions, adding any sort of suspension may or may not improve your listening. If you could find a modestly priced suspension system (inflated tube or bladder) to try for comparison against what I assume is your current non-suspended mounting, that should indicate if it would be worthwhile to then explore suspension options.

Sorry, there is no simple answer to your question.
Since my place is old and I live on the second floor, isolation is a must. I'm certainly getting feedback through the floor, no music above 90db. I bought a stand from a research equiptment re-seller, it's made by Newport, not audio jewelry, but not horribly ugly either. I'm in No-Cal so such business are available in my vicinity. It's built to handle very heavy things. I'm going to go for the Minus K since it's free from the need of a compressor, and is made in the US. We will see.
In MY experience, non suspended turntables need a solid foundation to the center of the earth... Spring aids, ruin the sound.
I put my Rockport Capella II on a pneumatic anti-vibration table, similar to that under the Sirius III, and experienced considerable improvement in term of background blackness with no negative effect that I could hear.

My friend put his Technics SP10 MK2 on a Minus K and got similar improvement in background blackness, but I was not familiar with the system so couldn't tell whether there was any negative effect.

However, the Minus K is not self leveling, so if the CG of your TT is not exactly at the centre of the platform you need to add some weight and move it around the platform to level it.
Let's see, if you have an unsuspended turntable on a solid unsuspended base, the structureborne vibration can get right up into the turntable platter, the tonearm and the cartridge. That being the case, I would probably opt for some kind of vibration isolation system.
I believe a cheap experiment would be to put some sort of inner tube, perhaps from a motorcycle tire, under the table and inflate it till it "floats". That should let you know more for little $. I have a VPI Classic that sits on a very old VPI isolation base. It has a sandwich platform, metal outsides over wood, and four foam wrapped springs in the corner. That sits on a wood rack I made, and on a hardwood floor. I can make the arm skip if I step near too heavily, but there is no acoustic feedback.
Or, you can place ten cryo'ed Baby Promethean Mini-Isolator Springs (from Machina Dynamica) beneath the solid base of a 100 pound turntable.
Or, a higher number of these special springs if the total weight is higher due to the weight of any supporting solid base already currently beneath the turntable base.

This is quick, low cost, and easy to level turntable.

Due to limitation of my own personal lifting strength, I have not positioned a turntable/base heavier than 50 pounds where I happened to need only five of the Baby Promethean springs to properly match the 50 pound load to be supported.

Vinyl reproduction capability is beautifully enabled.
Fingerpaws...oh yes you do have acoustic feedback...its just not at a frequency that you can call it that..however, it is blurring the sound coming from your turntable. Your fix (given the springy floor), is to mount a shelf on the wall for your Classic - affix it to studs. ( had one of those VPI spring things too). Get it off of that.... Get Bearpaws to replace your mini feet, and be delighted at how much more clear sound you get...more definition, more bass, clean, clean, clean.
Stringreen, I respect your musical knowledge and experience, but I believe you are wrong about "acoustic feedback". My simple understanding is that it is the airborne (i.e. acoustic) waves from output back to input. The most common example most of us have heard is an improperly set up microphone in a auditorium which howls from the sonic loop from PA speaker back to the mic.

Similarly, a turntable/arm/cartridge system is subject to the sonic energy, particularly low frequency tones, from the speakers. Wall mounting will only be effective if it moves the tt system away from a bass node loading area. It is not related to a springy floor. In extreme cases I've seen the tt system placed in a separate room from the speakers to minimize acoustic feedback. Fortunately most of us don't need to go that far.

This is why I suggested consideration of all three conditions for unwanted energy in my post above.
I highly recommend Minus K for non suspended turntable. I used to have my TW Acustic Raven AC-1 on Symposium Ultra sitting on top of machine shop bench which has 4 inch granite table top with steel legs. The whole thing weigh about 100+ kg without the turntable. Replacing Symposium Ultra with Minus K was remarkable and in my opinion, well worth the difference in price of the two platform. I don't have problem with subsonic rumble or acoustic feedback through the floor but sonic benefit alone is quite impressive. I also heard VPI Classic 3 to good effect on Minus K. There is even a review of Minus K on suspended table like Linn floating somewhere in the internet and there is a recent review of Minus K on Positive Feedback wiht some comments regarding Minus K vs older version of Vibraplane as well.
Pryso....I suspect that you are right, but remember too that sound travels as well through springy floors (and walls)...low tones travel unimpeded through windows (listen to the delivery trucks going by), but the glass is reflective of the higher frequencies....(cover all windows and/or close the draperies to hear the difference in the room. My suggestion of mounting a turntable on a shelf mounted securely into the wall studs eliminate a surprising amount of vibration transmitted via springy wooden floors...no its not perfect, but I have frequently been surprised at how much better the performance of turntables on walls is improved. Certainly this is only a suggestion and you are encouraged to do as you see fit...but if you try my suggestion, it very well might surprise you too. My recommendation of Bearpaws to replace the mini feet still apply.
"remember too that sound travels as well through springy floors (and walls)"

Absolutely, but my point is once the sound wave strikes/energizes a solid surface/object, the transmission then becomes mechanical, no longer acoustical. I consider acoustical to mean through the air.

In this view, sound waves do not pass through walls and windows directly. Coming from their source they strike a solid surface (drywall or glass in this case) where the energy is transferred by mechanical means. Some level of sound is reflected back, while some frequencies are filtered out (dissipated) in this process which is why higher pitched sounds may not survive. That transferred mechanical energy which survives then excites (vibrates) the air on the other side of the wall or window where it becomes acoustic again.

Consider the transformations with your violin. You pull the bow across a string which creates a mechanical resonance. If someone stands close enough to you they may hear the acoustic transmission of that string vibration, although it will be at a very low level. But the string vibrates the bridge as well as the air, which transmits energy to the soundboard (top of your instrument), which then vibrates air within the cavity of your instrument which becomes amplified by resonant reinforcement and comes out the f holes as acoustic sound waves which can now be heard from a much greater distance. (And yes, some acoustic sound is also projected out from the soundboard itself.) All this involves two different types of energy transfer.

I'm not trying to split hairs here and I don't pretend to understand this as well as a trained engineer or physicist. But I do believe if we are to address a problem it serves us to understand the causes as best as we can. This is why I break down vibration issues for turntables into three separate sources - acoustic, internal mechanical, and external mechanical.
One thing to consider about turntables, that's the resonant frequency of the tonearm and the cartridge and what it takes to excite the resonant frequency. As it turns out most tonearms and cartridges resonate at about 8-12 Hz. Thus, there will be no appreciable mechanical interference for the tonearm or the cartridge as long as vibrations with frequencies in the range 8-12 Hz are not present. Fair enough? But what is there to be afraid of, the acoustic energy in the room, generated by the speakers, will not go that low. And internal vibrations, produced by the motor, don't go that low. So what's the problem? The problem is the Structural Vibration produced by the Earth crust motion and traffic, subways, etc. It's the structureborne vibration that goes as low as 1-2 Hz and lower, but in particular contains frequencies in the critical range 8-12 Hz. Therefore, the most important thing to address is the Structureborne Vibration.
There is no question that your SP10 would benefit from some kind of isolation. Minus K has the advantage that it is mechanical and does not need a compressor. However, as was mentioned earlier, the load need to be centered and the unit needs to be properly sized for the load.

Albert porter uses a Vibraplane under his SP10 MK3 to great effect. You may want to PM him. I also use a Vibraplane for my suspended SME 30/12. The key with Vibraplane is to preload it as it is most effective if operating near its max. design load. The improvement for both my SME 10 and 30/12 was dramatic.

You might want to consider getting a large enough surface on either device so that you can also put the motor controller up on isolation. That too matters.

There is a recent review in which the Minus K was directly compared to a Vibraplane, and the guy preferred the Minus K, FWIW. Whichever device you decide to use, the supporting rack must be very solid and stable.
Excellent guidance and insights from Pryso. Always a pleasure to see coherent thinking. It's more effective to thoroughly understand the problem(s) you're trying to address and select solutions which address them than to try stuff willy-nilly... or to do nothing.

I could not afford a Minus K, but I did want to isolate my 90 lb., unsuspended TT from floor-borne vibrations, particularly as the floor is suspended wood (though well built and sturdily framed). In trying relatively inexpesive solutions, one finding was consistent and clear: the closer the isolation element was to the cartridge/tonearm, the more deleterious side effects were audible.

High mass, unsuspended tables are rightly prized for their massive dynamics and good low frequency response. Light weight, springy tables simply can't compete in this area because movements of the cartridge and arm induced by groove modulations can actually wag the table. High mass tables resist this, but will be susceptible to floor-borne vibrations, including those from the earth itself, passing traffic, etc.

Placing isolation devices immediately below the table did lower the sound floor, as expected, but it also diminished dynamics and bass response. In effect, I'd converted my unsuspended table to a suspended (if massive) one.

What to do? Increase the suspended mass by moving the isolation devices from beneath the table to beneath the stand that supports the table. My TT sits on a rack that, together with all the other equipment on it, masses over 500 lbs. Isolating this entire mass from the floor would address the floor-borne, earth-borne vibrations while allowing the high mass of the TT (plus 400 lbs of additional mass) to provide the solidity it was designed to offer.

Being relatively poor, I opted for a poor man's well engineered solution: Sorbothane pucks. Before you snear (as I once did) consider that I was NOT placing these in contact with the TT or anywhere near it. I tried that for laughs using Vibrapods and it sounded dreadful. OTOH, placing Sorbothane pucks of a durometer and number appropriate to the mass being suspended beneath the 8 feet of the entire rack made a nice improvement. Backgrounds were blacker and low level details more audible with no detectable penalty in dynamics or bass response. A win!

As a bonus, isolating the equipment rack from the floor helped isolate all the other gear on it too. Fewer audibly obvious benefits for a CDP or amp than for a super-sensitive phono pickup, but certainly no harm.

So... keep your high mass TT as rigidly connected to whatever supports it as possible. Isolate from the floor, yes!, but do so as far away from the table as feasible. Isolation requires movement and movement saps dynamics.

My $.02.
Consider for a moment that there are various vibration isolation designs. Of the mass on spring type, there can be vertical isolation, a combination of vertical and horizontal isolation and a combination of vertical, horizontal and rotational. There are three rotational directions of isolation - roll, rock and twist. No, I'm not talking about the Peppermint Twist. The definition of isolation in a particular direction is the ease of motion in that direction, thus good isolation in the horizontal direction would be characterized by being able to push the component easily in the horizontal directions. For turntables, which exhibit high rotational forces around the vertical axis, especially when heavy platters are involved, I suspect that isolation in the direction around the vertical axis is not desired, since rotational forces produced by the rotating platter would put the isolating system into oscillation, impacting the accuracy of the speed of the platter rotation. For that reason, I would constrain any isolation device so that only vertical and horizontal directions are addressed, keeping the rotational direction around the V axis stiff. If I'm not mistaken I believe that's exactly what Minus K did - constrain motion around the vertical axis by eliminating the isolation capability in that direction.
Excellent guidance, particularly from Pryso.
My 50 kg non-suspended soapstone plinth TT sits on 4 Audioquest sorbothane Big Feet, these act as shock absorbers.
This very heavy, in some extent suspended TT sits on plywood/aluminium plate that sits on 3 metal spikes to DIY metal rack filled with sand. The total weight of this system with all equipment on rack is more than 150 kg. Can´t be moved nor rocked by hand. This metal/sand stand has 4 spikes to floor.
I´m happy with the situation but I will replace the spiked plate with sandbox. I think this would make further progress. If I´m wrong please enlighten me.
While it's fairly accurate that heavy rigid support structures cannot be "moved or rocked by hand," the problem arises in the way seismic vibrations manifest themselves - by moving the entire building, not only up and down and side to side but also in the rotational directions. Hel-loo! For this reason even very rigid and heavy support systems can be easily moved by the seismic type vibration. As I mentioned earlier the effectiveness of isolation is actually a function of the ease with which the component can be moved in the direction of interest. Counterintuitive, eh?

I have installed the Minus K, it works just as advertised, no feedback which
has allowed an enormous amount in detail and image solidity to be

The process is a little jarring at first, my turntable is so heavy I needed to
it in pieces, then reassemble, it's not weighted evenly so I need to use
ballast to get the weight distribution correctly set-up.

I must admit, it's weird having such a heavy object virtually floating, it
reminds me of the film Gravity, I push it and it just a bit and it moves, then
returns exactly where it was. On start-up, the TT turns as the torque sets it
in motion, and then returns to it's place.

I can jump up and down next to it and it is completely impervious.

I am using a Newport stand made for scientific experiments. The legs frame
are made from extruded aluminum, hollow but extremely rigid due to the
form and how it all attaches. I bought it at a wholesale company which
specializes in medical and scientific equipment re-sale after companies
change gear, kinda like us actually.

Will need to continue the evaluation process but for now, I think it works
very well, haven't found any downsides.

Congratulations Crubio. I'm sure you will realize the benefit of isolation. On another forum I saw a photograph of the Rockport Sirius III. Interestingly, it sits on a custom stand designed for Rockport manufactured by Newport or TMC for their scientific lab air isolation stands/platforms. The Rockport turntable has the air isolation pistons on top of the stand just below the turntable plinth as opposed to at the bottom under the stand where the isolation would be further away from the turntable and be required to carry a much heavier load.

This design should deal more effectively with airborne vibrations hitting the stand which are thus isolated from the turntable. If the whole stand were sitting on isolation, airborne vibrations hitting the stand would make their way into the turntable.
I'm glad to see we have some serious audiophiles here.