Newbee: You can attribute variables in sonics due to a rack change in multiple manners. The most logical to me would be altering resonances in the room itself, especially over a narrow bandwidth. Some racks are going to contribute high frequency emphasis / ringing due to the excitation of metal. Some are going to contribute increased reflections / diffraction due to an increase in large, flat surface areas. Some are going to increase apparent low frequency content due to added mass / altered density in the room. Any of these given effects may become highly pronounced depending on if the room is phenomenally live, heavily damped, moved into different physical / acoustic locations from the last sample, placed upon a resonant, multi-node suspended floor, etc...
Everything in a room becomes part of the tuning of a system and what we hear, so taking all things into account, i don't doubt what Tom said or experienced. I just don't know if what he measured / heard is attributable to exactly what he thinks it is. Could be several factors coming into play. Sometimes what we think is obvious is actually a compendium of multiplying factors.
It is for that reason that critical analysis becomes necessary. That is, if you want to make headway in a consistent manner and apply what you've learned to various systems in different acoustic environments*. In that respect, that's why i disagree with Tbg. We do have the tools to take the proper measurements. Only problem is, you can take all the measurements that you want and go nowhere if you don't know how to interpret the recorded data or think that those specific results won't affect other aspects of operation. One link definitely affects the other links involved. Until all the links are of equal strength, your system is only as good as that weak link(s). Sean
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* The research that Ken at Neuance performed when designing his shelves is quite amusing, technically interesting and "real world". Most of his tests were conducted under very diverse conditions and installations. It was through the compilation of data and observations from varied scenarios that he arrived at the "near universal" design results that currently make up the Neuance line of products. As far as i know, Ken is still refining these designs based on further testing and feedback from end users. Like all things though, Neuance shelves have their design limitations and supporting great amounts of mass in a small area is one of them. Other than that, if you follow Ken's directions for proper use, you'll probably get the results that he speaks of on his website. Whether or not you like those results is obviously a matter of personal preference and how well the rest of the system and listening environment has been optimized.
