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Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

Re: Not so fast...

Hey Barry,

We're mostly in agreement, as usual. A good part of what we don't agree upon could be considered semantics, since we do seem to agree upon the fundamental concepts. I have read the article you linked a few times and it's got a lot of good stuff in it - I don't think there's anything I disagree with in it (with perhaps the exception of the claimed magnitude of sonic changes attained by putting footers atop a component versus underneath - I do agree there will be a change in sound, however).

The use of the word drain is the only thing we really disagree upon. I thought of using a bathtub anaolgy when I wrote my post, but decided against it because I don't feel it's entirely analogous, particularly the two bathtub scenario. Waves and particles do not behave alike.

The biggest problem I have with the two bathtub example is that there is nothing to represent the forces involved with a typical stereo rack. You have two connected bodies of water and nothing acting on them except gravity.

The only way to have a drain for vibration is to couple two or more things together. Since we're talking about a component being coupled to a shelf, which is eventually coupled to the floor, the component has quite a large vibration sink available to it - I don't see why couplers placed between a component and the floor can't be considered a drain, or at least part of a drainage system. Certainly less than 100% of the vibrational energy that travels thru those couplers returns to the component (yes, some amount will be reflected back, but always less than 100%). The only way to prevent some drainage from occuring is to achieve perfect isolation between an object and everthing else.

I can see how this issue can get very cloudy, since all couplers will transmit vibrations both ways between the coupled objects (which is technically a simplification, since vibration can travel in any of the six directions). I would agree that more floorborne vibration is typically entering the comoponent versus component generated vibration leaving, but that has more to do with the natural magnitude of these vibrations than anything else. If you were to do an analysis of what happens as an upward floorborne-generated wave meets a downward component-generated wave, it would be much the same as analyzing what happens when two waves meet in a pool - two frequencies, two magnitudes, two phases, one resultant wave.

Even in the presence of floorborne-generated vibration, less than 100% of component generated vibration returns to the component so long as it is effectively coupled to something.


-Pete


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