Dear Henry, Re your last post. First, can we be clear that I am NOT talking about air-borne vibrations? You keep going back to that in order to debunk something or other that I've written, and I keep reiterating that I am not so concerned with that phenomenon, because any audiophile with sense will have arranged his or her equipment so as to avoid or mitigate this potential problem.
Second, I completely share your doubts about the efficacy of tapping on a shelf to assess its goodness as a shelf. But in order to assess how a shelf does react to mechanical energy, entering from the support structure, from the floor, from the whole house shaking because a heavy truck is passing by outside, etc, or even downward into the shelf from turntable motor vibrations, any of which phenomena can set it into vibrating, tapping is as good as any other way to do it. The only purpose for the tapping is to be able to locate the nodes, and to prove they do exist, where the shelf essentially does not move. (As noted, you need a stethoscope for this.) My whole point was about the fact that the shelf will vibrate or resonate at a certain frequency, depending upon materials, mass, etc, and that at that frequency, the shelf does not physically move in the same way everywhere on its surface. There will be minima and maxima of movement. This was my argument regarding the pitfalls of using an outboard arm pod. And for the reason just described, a shelf makes a rather poor plinth. (You COULD use a 1000-lb block of stone, as is done for electron microscopes and other very motion sensitive instruments; I admit that very high mass and using non-resonant materials are ways to approach this problem.) I thought it was a reasonable thing to discuss, but it seemed to anger you instead. Encoding music into wiggles in a piece of vinyl and then converting mechanical energy of motion induced by the grooves into high quality audio is really a primitive notion; there are no perfect ways to do it.
By the way, I re-read your original post. Wouldn't you say that declaring the cartridge to be the center of the vinyl universe is more akin to the Ptolemaic view of the actual universe than to the Copernican one? And did you know that Copernicus merely revived an idea of the ancient Greeks about a heliocentric universe? (I did not know that; did some further reading.)
Dear Nicola, As is sometimes the case, I cannot tell whether you are mocking me or paying me a compliment. But can you please give me a specific example to prove your point, if you are serious? This thread is really about ideas, so I am offering ideas. I usually try to admit it,when something I write is based on hypothesis or a thought experiment, rather than direct experience.
