Turntable placement and isolation

The floor is the best place by far. Its very difficult to make a rack that is as good as the floor. I know. Mine was on the floor for years. When I finally developed a turntable rack better than the floor this is what it looks like https://systems.audiogon.com/systems/8367 Its a massive 750 lbs of solid cast concrete shelves, legs, and granite, with sand beds for the phono stage and turntable.

Mass is sort of the basis of a really good turntable rack. There's lots of different ways it can be done. You could more easily build a sand box and put that on top of any reasonably sturdy rack. 

However you do it, this is only the foundational first step. Next is springs. Because its all about vibration control. A lot of mass solves only a part of the problem because high mass physically cannot move a lot. It takes too much energy. It does however vibrate all by itself. Everything does. So what the mass does is eliminate large amplitude vibrations. Then springs are used to further reduce small amplitude vibrations. 

I've used the mass approach for decades and it works great. Recently I've started working with springs and they are great on the floor. So I have some ordered, hopefully they will be tuned to work well with the turntable, and will be able to let you know for sure. But for now, go with what we know for sure will work.

@newbee- Thanks for your feedback. I have a 2 inch thick maple butcher block which I would use to test the carpet scenario and report back. None of my components are going to be near the corners because of the exact reason that you mentioned. They are somewhat going to be close to the front wall. Components will start 18 inches away from the front wall at the center and they will be placed in two or max three rows ending near the speakers. The turntable position if on the floor would be on the third row after all components, starting from the front wall. So it will be centered between the two speakers and positioned slightly ahead of them. Thanks.

@millercarbon- Thanks for your feedback. Your system looks nothing short of spectacular and it is very advanced. I guess I am just a beginner...
I am a believer when it comes to isolation and seismic vibration control. I spent some time with springs and roller blocks to build my DIY platform for all of my components but couldn’t complete the project. The mass-spring low pass filter concept does work but the key challenge is to figure out the optimal combination of load and the natural frequency of the springs which will bring the resonance of the component and platform together to 3-4 cycles. The other challenge was to find a surface which will not ring. Many suggests marble, granite, etc for adding the mass but in my experience these natural stones without any damping always tend to ring. Then you get to handle the damping of these surfaces as well. It is at that point I kind of decided not to spend any more time on this research and may be look for a commercial product which is always going to be very expensive. 
So please keep in the loop with your spring isolation work.
On a separate note, did you notice any imaging degradation when you introduced the taller rack behind the speakers?
Thanks

It would be a lot easier for us to give you recommendations if we knew a little more about your Stereo. Wood floors are notorious for footfalls I would never never put a turntable on a 1 inch wooden platform on a wooden floor it’s like asking for trouble. All the best

indranilsen, I think you know where I was going with this but, in view of other comments I thought I'd amplify for what ever that may be worth. 

Needfreestuff is absolutely correct - 1)Wood floors can be lossy (as hell) and 2) I too would never place a turntable on a wooden floor. That said...

My thought was, starting out as I suggested, you would find out if the combination of carpet and pad under the 'board' sufficiently reduced vibrations from the floor. If so you might not need (as opposed to want) to use mass loading onto the floor. You might want to introduce some vibration reduction (insulating) materials under the board supporting the table(as in a boxed enclosure, like a sand box, with sand or thick latex foam) directly on the carpet. And don't be shy, jump up and down a couple of times and see what happens. If the arm doesn't jump out of the groove you might be good to go. What I'm getting at is trying to isolate the TT from the floor.

 If it does the first thing I would explore would be shoring up the floor under the TT. A pier or shim might do it and it would be cheap (if you can crawl under your house). If that works then you could mass load to your heart's content. Hell if you want you can even play with springs, although I must say I think springs introduce more issues/problems than other forms of isolation. 

I'm probably just a cheapskate but I find little on the market that has ever interested me, although highly touted (and overpriced). I think TT set up is the last great DIY opportunity. Enjoy. :-)