Dancing sand....

Originally Posted by
garmtz
.... Now, if we take a thin, flat sheet of metal with finely grained sand on it and we attach a speaker to it, we will see the sand creates all sorts of figures on the plate, because of the standing waves inside the material, creating some form of Lissoujous patterns. If we however clamp one side of the sheet, the patterns change radically.....Perhaps this can be measured by placing an accelerometer on one of the sides of the speaker and comparing the waterfall spectrum of the speaker coupled to a heavy stand (with Bu-Tak or a spike) with that of a speaker decoupled from it (with sorbothane or similar).
Textbook answer and the one I was looking for.
To take this a step further ...
Have you actually applied the dancing sand test to, say, the top panel? What happens? Any dancing? Or how about not sand, but talcum powder or sifted bread flower.
My bet is that there is no movement, no dancing. So what then? How much energy can actually be transmitted to the stand when it's of such low power that it can't even make a dust particle move?
Alan A. Shaw
Designer, owner
Harbeth Audio UK