Damn, I forgot to change the reply address... ------- Forwarded message follows -------
Chris Hellyar suggested: > If the problem is the lower frequency droning, you might be able to remove > some of it by isolating the machines from the floor.. As some of the noise > will be transmitted through floors, walls etc.. Many moons ago I did some work in an optical lab where vibrations of 100nm amplitude could really ruin your day. You even had to speak quietly. The isolation of their optical bench was a bit of a fencing-wire solution but the whole thing was based on decoupling the bench from the floor. The way they did this was to cut a big hole in the floor and dig a couple of metres down. Into the hole went two stacks of 44-gallon drums welded end-on- end. The drums (and the hole, presumably) were filled with concrete. On top of the concrete-filled drums was a couple of tyre-tubes and other damping materials, then a half-ton piece of granite which the optical workbench sat on. It wasn't ideal but it was good enough. Must have been fun putting it together... :) Cheers, - Dave David A. Mann, B.E. (Elec) http://www.digistar.com/~dmann/ "Why is it that if an adult behaves like a child they lock him up, while children are allowed to run free on the streets?" -- Garfield
