Isolation vs. Absorbtion

Sean, since you mention that your explanation of how cones do what they do was quoted at length by J Scull in Stereophile, can I ask for more explanation? No disrespect intended – for you are a sane poster whose views on AudiogoN I tend to pay attention to – but I did not find the S’phile quotation very enlightening. The diode metaphor of how cones pass vibrations one way has an obvious appeal to it, simply because cones look like arrows, but I’ve often wondered if there was a scientific explanation behind it. Your chain of thought about how cones work to drain vibrations in one direction and block vibrations in the other is quite logical and, as you say in your explanation, “it’s all quite simple.” However, in the end it all rests on the familiar proposition that cones pass vibrations one way – which, in my mind, you basically reasserted, rather than explained. ---------- Ideally, the contact area between a flat surface and the point of a cone that meets it is just that, a point. What difference does it make to vibrations on which “side” of the point there is flatness and on which side there is cone-ness? Again, the diode metaphor appeals in a visual way – vibrations get funneled through the cone in one direction but cannot squeeze into the point from a flat surface in the other direction; lower frequency (floor-borne) vibrations have more trouble than higher frequency (equipment) vibrations fitting through a small point – but I don’t assume that necessarily has any correlation to science. Is there any further explanation you can add for this proposition? ---------- BTW, this is a matter of intellectual curiousity, and I am not implying that I need to hear a scientific explanation before I believe that cones have an effect. Right now, I am comparing Mapleshade brass cones against the cones I currently have under my turntable, and there are differences to my ear. But, speaking of Mapleshade, that company sells higher-priced brass cones (Triplepoints) that have three “micro”-cones sticking up from the flat side of the cone. The cone is used point down, and the equipment rests on the points of the micro-cones rather than directly on the flat surface of the cone. The designer Pierre Sprey says that minimizing the contact between the equipment and the big brass cone improves the transfer of vibrations from equipment into the feet. Not that he gives a scientific explanation for this (though he might have one if I asked) ...just another example of differing points of view (no pun intended). -- Jayson

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!