Why Does A Concrete Floor/Spiked Metal Rack...

I agree with both of the above.

It's not just any concrete floor/spiked metal rack. It's your floor and your spiked metal rack. They have an interaction with your component which is not properly engineered. The first thing that I would do is get the sand out of it.In a coupled system, deadening the ringing is not the goal. Letting it vibrate is the goal. If it is truly well coupled and properly designed, the ringing is passing the vibrations to mechanical earth ground. Then try steel or hardwood shelves instead of MDF. And make sure that your CD player is on good audiopoints, so that the rack isn't defeated by the lack of good coupling at the start.

There is one other possibility, which we can't assess if we don't know what your CD player is. That possibility is that the CD player/cables combo may have a naturally overbearing bright sound, and that the rubber de-couplers actually created a condition that allowed colorations to be introduced that sounded more apparent in the bass.

I realize that may sound funny, but we all know that sometimes when an upgrade is made, it reveals shortcomings in some other part of the system. Perhaps the rack is functioning well, and thus revealed some other problems. I can't say for sure that this is the case, but it may be. Maybe now you are hearing what your CD player/cable combo is really doing.

If you want to fill the stand with something, use the Micro Bearing Fill from Sistrum. This is designed to enhance the performance of a tubular rack that is coupled, and not fight against it like sand does.

Those are my initial thoughts on the subject.

Unhalfbricking, sorry I made you go through the trouble of that. I really expected it to help. Perhaps there are some other issues that we're not aware of.

All forms of energy seek the ground state via the fastest route possible. Vibrational energy WILL seek ground, and it CAN be transferred there. Some vibrations CAN be dissipated as heat in certain materials, but that is definitely NOT the only way that vibration can be dealt with.

According to the Zener visco-elastic model, any energy which can not be visco-elastically dissipated, will be reflected or transmitted into the nearest adjoining surface. This threshold is easily reached at the vibration levels we are dealing with in the audio environment, with the materials typically used as "absorbers". Changing mass merely "tunes" the transmitted vibration frequencies. Going to very high mass increases the Coulomb's Friction to point where it will not be moved easily at the amplitudes encountered, and that is the direction that the heavy stone stands aim for. However, it is just as resistant to transmitting the energy away from the equipment, as it is into it - so airborne vibration is not dealt with at the equipment level with that type of stand.

Without question, a properly designed stand which provides a well-engineered vibration evacuation path that conforms to the laws of physics is the best route to take, because it will allow all forms of vibration to seek mechanical earth ground, no matter what the source of the vibration is. The only exception is the movement of the earth which will affect any system that is not an "active" control system.

Also, if your floor has a problem with not being stable, it is not a "fix" to compromise your racking system performance to try to compensate for an unstable floor. Fix the floor. Then let your properly designed racking system do its job.

Geoffkait, I agree that seismic movements will "outpower" any of the typical airborne vibrations in an audio system. However, short of a laboratory type active platform, there is nothing that an audio rack can do about that. No little rubber blocks or grommets are going to absorb and dissipate the energy that is moving your entire building around. They are going to move your rack, no matter what the rack construction is.

The airborne vibrations, however, can be more easily and successfully addressed by the equipment rack.

Onhwy61, I also was curious about that same thing, with the points going upside down on the racks and platforms, so I asked about it.

The explanation is that when the points are used upside down on the rack or platform, they are working in conjunction with the platform and another audiopoint in the other orientation directly coupled underneath it, and not in a "stand-alone" configuration.

According to the factory, this changes the behavior of the upside down audiopoint on top, to behave in accordance with the overall system to bring the vibrations downward to mechanical earth ground. It is not done in just a "willy-nilly" or "hopeful" way where they are "guessing" that it will do this. It has been designed by scientific theory, tested, and found to work. That is one of the things that sets Starsound products apart. They are engineered products, and not "garage" products. There are degreed engineers that are producing these designs.

To address your questions about vibrations "back-feeding" up the cones, they do not. The geometry and design of these Audiopoints precludes back-feeding of vibrations, when used in the proper way that is stated in the directions. What will happen though, is that if the entire floor is going up and down, the whole rack will go up and down with it. They can't stop the floor from vibrating, but they will not feed the regular vibrations back up into the equipment. If the floor is that active, then there is a floor problem, not a rack problem. Addressing the floor problem by bracing is the way to attack that, not by compromising the performance of the audio rack. If there is a major floor inadequacy and it is not possible to address it, like in a rental apartment, then maybe the Sistrum products aren't the answer to that. However, in a proper listening environment with a firm floor, they will do better than any de-coupling device.

I might add that the Aurios are not de-coupling devices, but are actually a form of coupling device that uses a ball between the cups that allows lateral vibrations to be dissipated by the minute "rolling of the ball". So you are actually doing some type of coupling right now with your Aurios. But with a different kind of design that may not be as effective as the Audiopoint design. If you like the Aurios, perhaps going further into even better coupling would yield even better results. Just a thought.