Best rack for non-suspension turntable?

I was on the same camp as Tbg until we swapped out the 400 lb slab that my friend had under his BAT tube amp and replaced it with a Grand Prix amp stand. He had tried many stands and ended up settling on a piece of slab that he was using under a vibration sensitive microscope at work.

When I first saw the Grand Prix and learned how much he had paid for it, I thought he was nuts. After I got to hold the Grand Prix which weighs like 10 lbs, I thought he was even nuttier. But when we placed the amp on the Grand Prix, our mouths dropped down to the floor. There were 4 of us in the room. We went back and forth several times just to confirm that we were not imagining things. That prompted me to look into racks. If you look at Sold Tech's white papers, you will see some test results of before and after vibration measurements. So, now I don't believe that "mass" is the ONLY solution.

FrankC

As I understand the Grand Prix, they are using the mass coupled to the floor in points to maximize the mass. I don't believe they are uncoupling at all. Mana stands has long used the same philosophy.

Be aware that using multiple layers of isolation materials can have a negative effect on vibration isolation. For example, if you have two platforms and two layers of isolation material, this is equivalent to a two-mass/two-spring system of coupled oscillators. This system has two resonant frequencies instead of one (so-called normal modes or eigenmodes). One of these normal modes will have a natural frequency higher than that of the equivalent one-mass/one-spring system and the other will be of lower frequency. Because the natural frequencies follow a sort of fractional power-law dependence on the masses and spring constants, the eigenfrequencies are not far (within an order of magnitude) of the value for the one-mass/one-spring combination. All other things being equal, this is not what you want because the goal of effective vibration control is to keep the natural frequency of the isolator well below that of the system that you are trying to isolate.

I have gotten excellent performance from Minus-k products both in my laboratory and in my home audio system.

I agree with Sdlevene... to a certain point. His comment is 100% true with regards to a spring system... if you use a spring or isolation material that bounces, particularly in few attachment points. If you use layers that are NOT springs and do not inherently contain bounce, then the opposite is true. A sheet of "insert your favorite material here" will have a lower resonance if adhesion covers most of the surface of which the isolating material and second sheet is affixed. This can be seen in thousands of examples of lowering resonance frequencies by attaching more mass. If two thin rigid substrates are held by springs... then both the upper and lower substrate will resonate at different frequencies AND be subject to bounce. However; if you glue the flat sides together covering enough surface area to couple to a different rubberized mass, the combination yields a MUCH lower resonance. A telephone pole has a lower resonance buried in the ground... a cheap plastic emblem glued to a brick wall has a lowered resonance, solidly glue a glass ball to your knee and the resulting resonance is lower :) Any material if affixed to more mass will lower it's resonant frequency. This is why the Symposium reference platforms are so amusing in interesting claims... they "de"couple using foam board which defeats the purpose entirely. They "de"couple the stainless steel layered masses with foam board, which is light and rigid... BUT light and rigid makes it into a great transducer. This gives a lowered resonance at very low frequencies, but actually amplifies high frequencies centered in sonic hearing. As an example NXT has made a mint attaching their products to this same foamboard/ gatorfoam material. Vibrations sent to a lightweight & rigid substrate WILL reproduce all the frequencies that it can given it's overall size and thickness. All transducers work this way. If your speaker cone had heavy mass, then it could not "vibrate" to reproduce the lower sound frequencies. The answer is properly decoupled mass like Audiav or advanced response servos like the Minus K... and the latter causes near field EMI... You don't have to believe me for this one, go buy an EMI/EMF meter to "see" for yourself how an active servo based solution actually induces undesired interference :)

The real answer: Neither is good for your application. Either way, they are both solid-to-solids and will carry vibration from the flooring and from/to other components. You should consider looking at different manufacturers, or possibly an on-shelf solution to actually make a difference.