Hi Ejlif. I only have time for a quick response on the bladder stuff at present, but here goes. Obviously you can buy a Vibraplane or Townshend etc. But to make your own you need a minimum of a top plate, a bottom plate, a bladder of some kind in between, and some kind of footer. The rules for the top and bottom plates are pretty much the same as for shelves - ie a trade-off between light, rigid, and acoustically inert. MDF is OK but I find thick perspex is good. The plates can be less acoustically inert than for a shelf since bonding the bladder to it reduces resonance. The Townshend products use steel plates, but use constrained layer damping inside to deaden the steel. The "best footer" question depends on what they sit between. Rubber or polymer is perhaps best when they sit between rigid but noisy plates, and cones are perhaps best when they sit between floppy/dead plates. The bladder is where it can get very tricky. The easy DIY methods are to use; squash balls sitting in O-rings - ie. the o-rings are to stop the whole thing rolling off onto the floor; a 12" or 14" bicycle inner tube (but it needs to have the valve refitted to the outside so you can get at it); one of those air cushions that haemorrhoid sufferers use; maybe even a whoopee cushion... you get the idea. But the squash balls do not provide much isolation, and the others (have not tried the whoopee cushion) suffer from a tendency for the component to pitch and roll rather than bounce up and down. So the commercial products attempt to overcome this by having complex bladders like you might find in a car with hydraulic or pneumatic suspension ie. some way of providing independent suspension. The cheapest and easiest way of doing this is to have three or four separate small bladders (if it was four then you would have one at each corner), but you may need to construct these by cutting down and resealing an inner tube. This is how the top-of-line Arcici rack achieves independent suspension (ie. it has separate bladders), and it has the benefit of providing a means of levelling components that have uneven weight distribution. Note that Arcici decided to move from four to three bladders some time ago - hopefully because they figured it worked better, so that might be a clue. I hope this is enough to get you started. I recommend you start by putting a 12" bicycle inner tube between your rack's shelf and lay another shelf on top of it, and then put the component on top and inflate the tube only so much that the top plate just floats. Then listen to what this does to the sound - it will free the sound from a lot of mud and grit and the music will breath. If the result is in the right direction for you, then you will have a better idea as to whether you want to go ahead and make a proper one. The result is not always beneficial. An already bright system can become too lively, or you may like the particular cacophony of your existing rack - but these problems are not born of the bladder. Otherwise the only downside I have found with bladder products is that sometimes, if you get the wrong amount of compliance in the system, you can get a "suck-out" effect in the audio band.
