Which cone's or platforms have helped?

CDC, the Russians built the ALFA subs out of titanium because its strength allowed them to dive to greater depths. FWIW, the Alfa subs were notoriously noisy, hence the need to operate at greater depths. My point is that I have not seen any scientific evidence that indicates that titanium controls resonances r vibrations better than other metals.

Having tried sorbothan (spelling?): warm, soft highs, loose bass. "Black Diamond" cones: hard, quick. Concrete block: dead, dull, turbid. Large hunk of steel: solid image, stable pitch."Audio-Resolution" platforms: open mids, dynamic, quiet backgrounds. These mostly seemed evident under the CD player.

This was just regular old white Styrofoam. The hard stuff. Well, it's not really hard, you can dent it with your finger, but I had several blocks that were used as packing material in a box that was just shipped to me.

My suspicions as to why it works so well is that it is mostly air with thousands of cells joined randomly.

I placed the components on the Styrofoam bases without the component feet attached to the component. Just the bottom of the component sitting on top of the block.

Sorry I can't be more descriptive of the Styrofoam, but I thought there was only one basic kind.

I was recently challenged by a friend who is a Sistrum Platform non believer to measure in room response of a system consisting of Thiel CS6's Krell amp and pre and Krell cd. All of this sat on a Stand Design audio rack. I used Audiocontrol RTA and calibrated mic as my tools. Using pink noise and taking spl measurement set at 80db. Variation in actual spl measured between 79 and 81.5 db. I did not at first realize this variation was caused by the compression and expansion of the room itself. WE then took frequency response measurements at the same level and recorded these and stored them to the rta. Step two was to add the Sistrum Platform under the Krell CD player and to repeat the same test in the same identical manner as the first. The SPL measurement shocked me! The variation in SPL was less and also flucuated at a slower rate. I really thought the spl would increase with the addition of the platform because I could always hear much improved dynamics with the use of Sistrum products. Next we took frequency response measurements and stored these as well. Upon comparison of the 2 curves my friend and I both could see marked improvement in the lower mid bass to mid range shape as well as the range from about 3k on up. This improved curve was now more of a flat line with the use of the Sistrum Platform. This was the first time I had ever measured a system with and without the platforms. I really did not think that all the improvements I knew I have been hearing with the platforms could actually be measured so easily. My friend stated he thought the reduction in spl related to less distortion when using the Sistrum platform. This was my perception when listening with these devices in place. More detail and separation, much lower noise floor and much greater contrast. Let me state I do not make it a habit to walk around with an RTA taking measurements of my system or anyone else's. The texture of the music is the turn on for me. I did however thank my friend for the Sistrum challenge.

Jazzdude, isn't it saying that titanium is a better conductor of vibration in that the sub was noiser, thus allowing vibration to resonate better? I would think a quiter sub would be absorbing or otherwise not conduction vibration, thus less noise.