Isolation vs. Absorbtion

I don't buy the mechanical diode idea as anything more than an analogy (and all analogies are inaccurate), and tend to agree with Mapleshade that for a cone to do its thing it would ideally have a point on both ends - hence the Mapleshade idea of three points on one end and one on the other. Conventional cones sound the best when the flat side is up against the surface that is vibrating least (the equipment), since the flat side does the worse job. Hence also why cones can sound better if they are bolted firmly to the bottom of the equipment. I reckon cones between component and shelf do their job because they release energy very quickly at the pointed end. This reduces smeering, but creates peakiness. The sonic differences between cones depend on hardness (speeds the release of energy), resonance/damping (determines the peakiness) and mass (slows the release of energy), but are also profoundly influenced by the shelf material that the pointed end rests on. The more the shelf material is like the cone material, the more you will hear the peakiness of the cone. In my opinion, cones are only good as an antidote to a shelf that has too little rigidity and too much mass (such as MDF). This is just my theory developed from my experience, no more than that, and I respect the fact that other theories presented here may be more accurate.

Redwiki - Based on yur research, what would you recommned instead of cones for equipment sitting on glass shelves? My tubed amps amd pre amp sit on glass-shelved Target amp stands. I tried BDR cones and they improved focus/accuracy vs. the crappy stock rubber feet, but I admit I've not done further experimentation.

Redwiki - Never mind. Just read your other string. Will try the EAR devices.

Thanks for your comments on my questions everyone!

I'll try to address both Dan and Jay's questions here as briefly and simply as possible while touching upon Redkiwi's comments. In terms of the MGD rack, i had originally added large "fender washers" between the locking nuts on both the top and bottom of the shelves. Michael said that this was a big no-no, but the nuts seemed to be digging into the shelving material quite a bit and leaving "uglies". He told me that if this was happening that i had the nuts too tight. Tightening these down quite a bit was the only way that i could keep the rack from swaying or leaning to one side (my floor is not level). I was EXTREMELY meticulous as to having the rack level on all shelves and keeping it rigid made that a LOT easier. I have since taken to "playing" with the tightness of the top clamping nuts on each shelf. This has greatly affected the tonal characteristics of the bass, amount of air and ambience along with the overall "pace" of the system. It has also resulted in a rack that is slightly less stable due to less rigidity. That might be a lesson in itself. As to cones or coupling in general, i DO agree with Redkiwi's comments that cones that are securely mounted to a component and not just resting on top of them is more effective. The cones become an active part of the chassis when this is done. In effect, you no longer have an individual component and cones but a one piece chassis with better transfer characteristics. As to explaining the transfer function vs. surface area and coupling, i am not a mechanical engineer nor do i have any background in such. Most of my "deductions" were arrived at from a "logical" train of thought and experience. Reverse my "logic" in the article that Stereophile published. Instead of thinking about how the "arrows" were driven down into the shelf, see how easy it is to drive a nail into the wall with it pointing the wrong direction. There is OBVIOUSLY a major difference in how efficiently the energy is transferred depending on the shape and amount of contact area between the two mating components. Another KEY factor in this equation was brought up by the "Kiwimeister" in terms of the materials used. Redkiwi's comments about specific devices sounding "peaky" or having common sonic traits has to do with the overall transfer of energy between the entire component / shelf / rack / floor / room synthesis. There are obviously vast differences in densities and ranges of resonance in various woods, polymer's metals, etc... Which material works best where or how all of these will blend together is anybody's guess. After all, while we look at each component as an individual link in the chain, the system IS the WHOLE chain and sums everything as one. For those that have electronics background, think of a circuit with dozens of components in it. Even though each diode, resistor, capacitor, inductor, etc.. has specific characteristics, they can all be summed up as one big "MASTER" complex impedance as described in "Thevenin's theory". In our audio system, we could call it "the MASTER complex resonance". It's just a combination of all of the smaller resonances added and subtracted, etc... How to arrive at what sounds good to us is a pretty complex ordeal, just like the above described circuit. While i know that Redkiwi has spent a sizable amount of time investigating some of these specific areas, he may not have come to any "solid" conclusions. To make any real progress in this area would really require test instruments and extensive notes and documentation for various situations and installations. There are SO many variables involved in terms of different isolation / damping devices and designs along with materials for those AND the shelving that you would literally need a lifetime to document them all. It is hard to imagine that ANYONE knows the answer to ALL of the following questions: 1) Do you isolate component A or dampen it ? 2) Do you know which shape or style of isolater / damper works best ? 3) Do you know which material to use for the isolator / damper ? 4) Do you know the optimum place on the chassis of the component to place the isolation or damping device ? 5) Do you know what material, shape, size and weight to make the shelf that the component will be resting on ? 6) Do you know if the shelf / rack should be rigidly coupled to the floor or if it should be isolated ? Etc... This is the reason that so many tweaks exist. There are NO answers set in stone. It is all a matter of trial and error as to what works best, what works poorly and what doesn't work at all. While keeping a notebook on such things might be considered "anal", it might actually produce some very interesting results. I simply offered some of my thoughts / observations as to what i've encountered so far and Jonathan "ran" with it. Like the rest of you, i'm still guessing, learning and "playing it by ear" too : ) Sean > PS.... To all of the "non-tweakers", hope you had a good laugh : )