Isolation vs. Absorbtion

If there is an answer, I haven't found one. You mention soft pads isolating a CD player - if only.. All they do is change the resonance to a lower frequency - whether this is better or worse is a matter of taste. Arguably a soft pad allows the vibration to last longer, whereas a cone causes the energy to be released quickly. The former does damage to the perceived rhythm and timing of the music, whereas the latter can induce peakiness in the mid-band. Currently I prefer using E-A-R elastomer feet which are nothing like as soft as sorbothane (which sounds ghastly), and nothing like as hard as any cones. Whether or not shelves should be supported by spikes or soft footers depends on the shelf material. Spikes on a hard shelf like glass etc tend to sound awful, but better with soft shelves like MDF. The rack itself and damping of the shelf are other factors. Alas, simple answers escape me despite my efforts to date.

equa: i was hoping rekiwi would respond first to your thread query. he's shared with us in erudite posts his experiences testing "footers/shelf material." i recommend you review the thread of that name. i just wanted to comment on your observation that this hobby is informed with "subjectivity and contradictuions." you are right, of course, but these characteristics are what give it life and, indeed, form the basis for sites like this one. as redkiwi attests: there are no "simple answers" to the paradoxes you'll encounter if you get deeper into the hifi world. don't let this bother you or you'll go a little nuts. sit back, ponder and then enjoy the music as your journey lengthens. good hunting. -kelly

Redkiwi makes some very valid "points" : ) My experience is that i have noticed EXTREME differences when changing racks and isolation devices. I had a "home-brew" all wood rack that i had everything dialed in on very nicely, but i added more components and needed a bigger rack. The way that i had built this rack did not lend itself to "adding on" any further shelving. I went to a Michael Green Designs Deluxe Just-A-Rack and it COMPLETELY changed the way that system sounds. It was SO obvious that i had to put a different amp into that system to "re-balance" it. Upon further consultation with Michael, it turns out that i had tightened the nuts down too tight on the shelves and this was causing the massive (read as "less than good") changes that i had noticed. I am currently in the process of "fine tuning" the characteristics of the rack and it is making a VERY noticeable difference in bass output and tonality, timbre of instruments, attack and decay characteristics, etc... Quite honestly, i would have never believed that something like this could have made SUCH a noticeable difference in a system. As others here have mentioned, this is more of a "black art" involving a LOT of trial and error. While some of this stuff can be understood logically, as to what works best and where at in the system is strictly guesswork and experimentation. Not to toot my own horn, but i covered some of the logistics of why cones couple / uncouple in the February issue of Stereophile in Jonathan Skull's "Fine Tune's" column. He thought that i had hit on something with my original post on that subject and thought it might be worthwhile to share it with others that might not have been able to see it on the web. As such, some of it was slightly altered for publication but the "guts" of the post remained intact. The bottom line is that one MUST be VERY familiar with the system in the first place before subtle changes can be easily detected. Until you have achieved a very good foundation that your basically happy with, doing small "tweaks" to fine tune it might end up taking you in the wrong direction. Hope this helps. Sean >