Turntable isolation platforms

We're all talking about the same thing here. I've just provided a alternate, general way to understand what's going on, not just with turntables but speakers and components with noisy transformers as well. Mass on spring works well at low frequencies because of bass energy loss in the spring. Sand is likely needed for the high frequency isolation through absorption.

If you place a lightweight platform on spikes on a suspended wood floor without carpet, I doubt your going to get low frequency isolation.

That gets to my point, the floor is acting like a diaphram which has to have relatively even movement of soundwaves to be an effective transducer. Place a heavy weight in one spot and you have a node or lower energy zone. Sound waves traveling through the floor are reflecting off the perimeter of that weighted floor spot and travel around it or through supporting beams to other sections of the floor that allow vibration. It's like a large scale piezo-electric buzzer for bass.

Cones or vibrapods work on components because weight is concentrated under the metal chassis effectively conducting or draining vibration out of the component. Unlike the floor, the metal in the chassis doesn't change density near the cones. Cones work best with lossy plinths that dissipate energy.

The effective channeling, isolating and dissipation of vibration energy can be achieved by knowing when to minimize boundary reflections and when to incorporate loss. It's all wave energy, highly similar to RF.

brotw70

brotw70
We’re all talking about the same thing here. I’ve just provided a alternate, general way to understand what’s going on, not just with turntables but speakers and components with noisy transformers as well. Mass on spring works well at low frequencies because of bass energy loss in the spring. Sand is likely needed for the high frequency isolation through absorption.

>>>>At the risk of you thinking I’m picking on you, we’re not talking about the same thing here. In fact, mass-on-spring isolation is better (more effective) as you go up 🔝 in frequency. By the time you get to 25 Hz on the way up 🔝in frequency - even for a modest iso system - the effectiveness of isolation is more than 95%. By the time you get to 30 Hz it’s 99.5%. So, it’s more effective for high frequencies than for very low frequencies. Hel-loo! Not to rub it in too much but mass-on-spring isolation is not due to losses in the spring. It’s more complicated. That’s why it’s called mass-on-spring. It functions as a mechanical low pass filter with a 6 dB per octave characteristic.

Ok, had to look that up. Mass on spring looks effective for isolating turntables through other means. I'm more interested speaker and component vibration solutions that drain sources of vibration to the floor. Haven't seen many spring solutions for those. I think springs just solve the floor moving up and down problem rather than lateral.

I would go to your local granite countertop site and ask them to cut you a 1.5 to 2 inch thick piece large enough to place your table on. all the imaging greatly improves and feedback becomes a non issue.

For most stuff millercarbon's sandbox solution will work fine. It is just a mater of making it look good. There is only one problem I can think of and that is the floor. Concrete floors are perfect for Hi Fi rooms because they are so stiff and non resonant. Wood floors however are spring boards.
More mass = lower resonance frequency = more bounce. You can really give yourself a foot fall problem this way. I have seen tonearms go airborne. With a wood floor there are only two solutions I can think of. A wall shelf which was previously mentioned which works great as long as there are not little ones crashing into the wall or a well designed suspended turntable. 
The Isoacoustics platform should isolate you from that "rumble" you have noticed. It will not isolate you from foot falls. If you are on a concrete floor the Isoacoustics platform will be all you need. 
Going back to turntables, the SOTA is a brilliant design actually more so than the Basis or SME. All three tables have properly designed and tuned suspensions. You can jump up and down in front of all three and nothing will happen even if you have crappy floors. But with the SOTA the suspended platform is internalized so you can bump up against the plinth and nothing will happen. When  placing the tonearm I can use the plinth as a steady rest. You can not do this with the other turntables. I have both a SOTA and an SME. The reason I got the SME is that I wanted to use a Kuzma 4 point 14 and SOTA does not make a turntable you can mount this arm on. If they did I would have gotten it. The SME is a great turntable but the SOTA is nicer to use and the Macassar Ebony plinth is drop dead gorgeous. The SME is...industrial. 
Having a properly isolated turntable is just as, if not more important than getting the tonearm set up dead on. If you get one of the above turntables you do not have to spend money on a special stand or shelf. You could place any of these turntables on a collapsible card table and they would work fine.